No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Nitrogen use efficiencies to grow, feed, and recycle manure from the major diet components fed to dairy cows in the USA
Abstract
Crops and livestock transform a general range of 20% to 50% of applied nitrogen (N) into product N (e.g., grain, forage, meat, milk). Most N not incorporated into agricultural products is lost to the environment. The objective of this study was to quantify soil N input (fertilizer N, biologically fixed-N) incorporation into the major diet components fed to dairy cows, diet component N secretions in milk N and excretion in manure N constituents, and manure N recycled back through the feed supply. Alfalfa for silage (AS), corn for silage (CS), corn grain (CG) and soybeans (SB, eventually solvent-extracted into soybean meal, SBM) were enriched in the field with fertilizers containing the stable isotope ¹⁵N. Each ¹⁵N-labeled diet component was fed individually to twelve mid-lactation cows (3 cows per ¹⁵N-enriched diet component) as part of a total mixed ration (TMR). Proportions of each component’s ¹⁵N intake (¹⁵NI) recovered in milk, feces, fecal undigested dietary N, urine, urinary urea and retained by cows were determined during a 4-day ¹⁵N feeding period and 4 days thereafter. Diet component ¹⁵N manure was applied to field plots and ¹⁵N uptake by corn for silage was determined over two succeeding years. The wide range in total ¹⁵N recoveries (% ¹⁵NI), greatest from cows fed AS (67) followed by CS (61), SBM (61) and CG (54) indicate significant differences in diet component ¹⁵N retention by cows. Relative ¹⁵N recoveries (% of total ¹⁵N recovered) in milk were greater (and statistically similar) from cows fed CG and SBM (average of 29.2) than from cows fed AS and CS (also statistically similar, average of 18.4). Relative ¹⁵N recoveries in feces were greater (and statistically similar) from cows fed AS and CS (average of 42.2) than from cows fed CG and SBM (also statistically similar, average of 30.7), and ¹⁵N recoveries as fecal undigested dietary N were greatest from cows fed CG (2.5) followed by AS and CS (average of 2.2) and SBM (<1). Relative ¹⁵N recoveries in urine (average of 39.7) and urinary urea (average 34.0) were similar across all diet components. Over the 2-year field study period, greatest manure ¹⁵NUE (% of applied manure ¹⁵N recovered as corn silage ¹⁵N) was obtained in plots amended with manure ¹⁵N derived from SBM (38.2) and lowest from CS (30.5). The greater total N use efficiency (percent N inputs incorporated into milk N plus corn silage N) for SBM (68.3) and AS (51.5) than for CG (47.4) and CS (40.6) can be attributed mostly to differences in N use efficiencies of the biologically-fixed-N and fertilizer N to grow diet components. A balance between corn, alfalfa and soybeans in dairy cropping systems should be encouraged to not only enhance N use efficiency in feed and milk production and manure N recycling, but also to capture many of the long-term benefits associated with corn-legume rotations.
... 15 N labeling techniques have contributed considerably to our understanding of post-absorptive N metabolism (Lapierre and Lobley, 2001) and change in natural abundance of 15 N has been used successfully to delineate the relative contribution of digestion and metabolism to NUE in dairy cows (Cantalapiedra-Hijar et al., 2016). The experiment reported here was part of a multidisciplinary project that used 15 N labeling technique to elucidate how the change in diets may impact manure N emission, soil N dynamics, N losses, and whole-farm N utilization (Powell et al., 2017). In the animal component of the project, which is reported here, we hypothesized differential relative partitioning of N to milk, urine, and feces from alfalfa silage (AS), corn silage (CS), corn grain (CG), and soybean meal (SBM), which are four commonly used feed ingredients of dairy rations typical of the Midwest of the USA. ...
... The protocol used to label dietary components used in this study was described in Powell et al., 2017). Foley catheters (24 French, 75-ml balloons, C. R. Bard Inc., Covington, GA) were inserted into the bladders and collection of urine (into closed containers), and feces (into buckets from a wooden board placed over the gutter) proceeded from day 12 to 19 at 0400, 1000, 1600 and 2200 h. ...
... These samples were stored at -20 ºC for further analysis. The remaining urine and feces were transferred to plastic bins and stored for a subsequent 15 N labeled-manure field application study (see Powell et al., 2017). Fecal samples were dried in an forced-air oven (60º C, 48 h) and ground 7 through a 1-mm screen in a Cyclone mill. ...
The objective of this study was to determine the relative partitioning of N in individual feed within a diet (alfalfa silage [AS], corn silage [CS], corn grain [CG] and soybean meal [SBM]) into milk, urinary and fecal N in lactating dairy cows. For 11 days, twelve multiparous Holstein cows (means ± SD; 264 ± 18 DIM) were fed once a day an unlabeled TMR formulated to contain (DM basis) 335, 325, 190, 125 and 25 g/kg of CS, AS, CG, SBM and a mineral-and-vitamin premix, respectively. On the morning of day 12, cows were blocked by milk yield and randomly assigned within block to one of four dietary treatments constructed by replacing one feed ingredient of the unlabeled TMR with its corresponding ¹⁵N-labeled ingredient (grown with ¹⁵N-labeled fertilizers). Cows were fed dietary treatments for four days (day 12 to 15) and the unlabeled TMR from day 16 to 19. Feed intake and lactation performance were measured daily whereas total fecal and urinary collections were conducted on each cow every 6 h from day 12 to 19. Feeding ¹⁵N-labeled ingredients had no effect on DMI (mean ± SD; 22.0 ± 2.0 kg/d), milk yield (26.4 ± 5.2 kg/d), N intake (631 ± 25 g/d), milk protein concentration (34.7 ± 3.3 g/kg), and N use efficiency (milk N/intake N; 235 ± 46 g/kg). By the end of sampling, 61% of ¹⁵N was recovered in milk (13.6%), urine (24.1%) and feces (23.3%) suggesting substantial distribution of ¹⁵N in tissues with slow turnover rates or growing actively (e.g., fetal tissues). The ratio of ¹⁵N atom % excess (APE) in urine to ¹⁵N APE in milk and the ratio of ¹⁵N APE in feces to ¹⁵N APE in milk measured on the fourth day of feeding the treatment TMR were used as indicators of relative N partitioning. The ¹⁵N APE urine/milk ratio was greater for AS (1.51) than for CS (1.30), which in turn was greater than for the concentrates (1.02 for CG and 0.94 for SBM). In addition, the APE ¹⁵N feces/milk ratio was greater in silages than concentrates (2.12 vs. 1.20, respectively). Interestingly, the main route of ¹⁵N excretion from AS was fecal rather than urinary. Overall results suggested more excretion of urinary N and fecal N relative to milk N secretion for silages than for concentrates.
... Colorimetric titration using hydrochloric acid was performed to obtain nitrogen content. Powell et al. [91] determined nitrogen content in manure using Elementar VarioMax CN analyzer (Elementar, Germany) [91]. Liu et al. [23] determined ammonia nitrogen content using formaldehyde method in China National or Industrial Standards (GB/ T3600-2000) [92]. ...
... Colorimetric titration using hydrochloric acid was performed to obtain nitrogen content. Powell et al. [91] determined nitrogen content in manure using Elementar VarioMax CN analyzer (Elementar, Germany) [91]. Liu et al. [23] determined ammonia nitrogen content using formaldehyde method in China National or Industrial Standards (GB/ T3600-2000) [92]. ...
Investigation of composition of biomass is an important pre-requisite for determining its suitability for various downstream applications. In recent times, food waste has emerged as a valuable biomass feedstock which could be valorized for production of fuels, chemicals and materials. Prior to use as a feedstock, it is pertinent to perform a detailed composition analysis and gather critical information about nutrient content including carbon, nitrogen and lipid. Additionally, analysis of minor constituents in food waste is significant to understand the possibility of their toxic or inhibitory effects during biotechnological conversions. Another abundant biomass source is manure which primarily arises from animal feeding operations. The major application of manure is land-applied fertilizer besides the recent investigations for fuel and energy. These intended applications demand complete characterization of nutrient content and quality. Thus, this chapter is focused on characterization and analysis of food waste and manure. Methods for sampling, handling and pretreatment of food waste and manure are discussed. Furthermore, a detailed nutrient analysis and equipment used for analysis is described. We further discuss the application of food waste processing techniques which could facilitate the characterization, treatment and product recovery.
... The continuing shift toward feeding more high-silage diets has stimulated NUE research on dairy farms ( Table 1). As N transformation on dairy farms are interrelated and complex, Barros et al. (2017) and Powell et al. (2017) applied stable 15 N isotope analyses to measure relative partitioning of N at the whole farm scale and from alfalfa silage, corn silage, corn grain, and soybean meal into milk, urine, and feces. Based on these 15 N recovery data, the authors reported differences in undigested dietary N in feces, indicating that differences in dietary components could impact long-term contributions to stable organic matter (OM) in manure-amended soils. ...
... Most research on fecal N (or more generally manure organic N) have focused on characterization and mineralization rates for N cycling (Agomoh et al., 2018;He, 2012;He and Zhang, 2014;Wang et al., 2018). Generally, fecal endogenous N (i.e., microbial cells and sloughed gastrointestinal cells) is rapidly mineralized and available to crops, while undigested dietary N in feces is not readily available to microbes and could be a stable component in soil organic matter (Powell et al., 2009;Powell et al., 2017). In lactating dairy cows, endogenous N represented an average of 17% of feces-N (Ouellet et al., 2002) Another gaseous component from beef and dairy manure is N 2 O, which is a potent GHG implicated in global climate change (Külling et al., 2001). ...
The ever-growing global population puts enormous pressure on the food production systems by always demanding increased food production. In the last four years, the amount of milk produced in the US has increased on average by 1100 metric ton yr-1, with the number of milking cows (Bos taurus) increasing by about 41,000 animals over the same timeframe. Managing the manure produced by livestock operations is one of the major challenges in food production and the one that has the highest potential negative impact on the environment. Most of the N required by animals is provided in the form of protein present in the feed. In general, animals excrete a large quantity of the N consumed (as much as 95%) either in the urine or in the feces. Changing the total amount of protein in feed is an option to reduce the amount of N in manure. For P, feeding too low P content can be dangerous for the lactating cows; feeding rations with less than 0.31% of P leads to P translocation from bone deposits. The amount of N and P present in manure is directly related to the amount of N and P in the feed. Increasing feed N and P as a percentage of feed dry matter causes a significant increase in the amount of N and P in the manure. Understanding manure nutrient composition is key for developing sound strategies for manure reuse in the farm and minimizing the negative impacts of manure on the environment.
... The feeding of 15 N-enriched forage, silage or grain to animals is the best guarantee of obtaining isotopic uniformity in feces and urine, but this approach is time-consuming, complicated and expensive. For example, Powell et al. (2017) fed four 15 N-enriched diets to three milking cows per diet over a period of 2-4 days which required a daily dry matter intake of 25 kg per cow. This exercise required detailed calculations of land area, amounts of 15 N-labeled fertilizer, predicted crop yield, crop N uptake and N fertilizer use efficiency, in order to provide sufficient labeled materials, which varied in 15 N abundance from 0.74 to 2.40 atom% 15 N. ...
... The processing and storage of the feed components and the collection and storage of excreta four times per day for 4 days from individual cows added to the logistics attendant on this approach. For example, Powell et al. (2017) generated 324 15 N-enriched samples of feces with an equal number of labeled urine samples. Specialized equipment such as indwelling catheters were also used to ensure separation of feces and urine , thus increasing the cost and degree of sophistication. ...
Abstract
The increased demand for organic farm products, and the attendant restrictions on the use of synthetic N fertilizers in both traditional and organic agriculture, has focused attention on the efficacy of organic sources of N, including animal excreta. However, questions arise in regard to the agronomic and environmental benefits of excreta as alternative sources of N. These questions are best addressed through the experimental use of 15N-enriched excreta, which enable the labeled source to be unequivocally traced through the soil-plant-atmosphere continuum, which N difference or N equivalence techniques cannot achieve. In contrast to organic and inorganic N compounds that can be purchased commercially with a specified 15N label on the component N moieties, 15N-enriched excreta must be prepared by the investigator. The methods of production and the uniformity of labeling of the components of 15N-enriched excreta (feces, urine) and their admixture (slurry), the N use efficiencies of excreta in crop pro- duction, and comparisons and interactions of excreta with synthetic N sources are reviewed. Losses of N from excreta-amended soils to the environment and the residual N value of excreta in crop sequences are also examined. It was concluded that while similar agronomic and environmental issues surround the use of both synthetic fertil- izers and excreta as sources of N for plant nutrition, the processes differ in intensity and duration both spatially and temporally.
... To recycle old products, enterprises should not only carry out recycling advertising and publicity, build reverse logistics equipment and transportation system, but also carry out supply chain collaborative scheduling. More importantly, consumers should have good environmental awareness [14,15]. Recycling old products in the environment with good environmental awareness of consumers will reduce the cost coefficient. ...
To improve the integrity of the supply chain and get the optimal joint scheduling of the complete supply chain, in this exploration, first, the supply chain related theory is elaborated. Then, the dynamic model of product recovery in enterprise joint scheduling is established. Finally, based on the differential game theory (based on the continuity of nonlinear differential equation function) and Hamilton function, the optimal scheduling strategies with manufacturer and retailer as the main recycling body in the complete supply chain are calculated respectively. The results show that the product recovery rate with manufacturer as the main recycling body is higher than that with retailer as the main recycling body. There is no transfer price in the recovery based on the manufacturer. However, in the recovery based on the retailer, if the transfer price increases, the product recovery rate of the system will also increase; if the transfer price increases, the manufacturer’s instant profit will appropriately increase; if the transfer price value is high [Formula: see text], the manufacturer’s instant profit is higher. If the transfer payment is low [Formula: see text], the instant profit of manufacturer with manufacturer as the main recycling body will be first lower and then higher than that with retailer as the main recycling body. When the system is stable, the instant profit with the manufacturer as the main recycling body is higher than that with retailer as the main recycling body; the total profit of the manufacturer with the retailer as the recycling body is first lower and then higher than that with the manufacturer as the main recycling body. Whether the transfer payment is high or low, the retailer’s profit level is higher when the manufacturer is the main recycling body. When the retailer is the main recycling body, the retailer’s profit level is inversely proportional to the transfer payment. Finally, in the centralized supply chain environment, enterprises can maximize their total profits and promote the good development.
... The difference between the total faecal N content and the undigested dietary N (mainly fibre-bound N determined as N-NDF) allows also to estimate the amount of metabolic N (microbial N and endogenous N secretion) which represents the most soluble N excreted with faeces, chemically described by Van Soest (1994) as N soluble in the neutral detergent solution (N-NDS). The faecal N-NDS is highly influenced by feed quality and digestibility (Schuba et al. 2017), and represents, from an agronomical point of view, the source of N rapidly mineralised in soil (Powell et al. 2017;Pagliari et al. 2020). In fact, decomposition of organic matter (OM) in soil (and consequently rates of organic C and N mineralisation) is affected by the biochemical fractions of decomposing material. ...
Data about diet and digestion process of cattle are important for the fine-tuning of the diet and from an environmental point of view. Given the capacity of the near-infrared reflectance spectroscopy (NIRS) to provide easily, quickly and cheap data its ability in predicting dietary and faecal chemical composition, fibre-bound N and total-tract apparent digestibility (ttaD) of beef cattle were tested. The ttaD was estimated using the dietary and faecal undigestible neutral detergent fibre (uNDF) as an internal marker. A total of 172 pool faecal samples and 164 total mixed ration (TMR) samples were randomly collected 24 h post-feeding across the fattening groups of young males and females Charolaise beef cattle. Both TMR and faeces were analysed chemically and through visible/NIRS instrument. Calibration models were developed using a modified partial least squares (mPLS) regression analysis and tested by a leave-one-out cross-validation procedure and the best calibrations were selected based on various parameters including the coefficient of determination of calibration (R²CrV) and the residual predictive deviation (RPD). The overall composition of TMR and faeces were similar to that reported in literature and the coefficient of variation was higher than 12% for most of the parameters studied. The NIRS was able to accurately predict the ADF, nitrogen (N), and ash content in the TMR, whereas in faeces only the ADF prediction was acceptable. The ttaD and total-tract true digestibility of N using the uNDF as an internal marker were inaccurately predicted both in TMR and in faeces (R²CrV ≤0.66; RPD ≤ 1.71).
• Highlights
• Near-infrared spectroscopy was not a suitable technology to predict total tract apparent digestibility.
• NIRS was able to accurately predict the ADF, nitrogen and ash content in the TMR.
• NIRS was able to accurately predict the ADF in faeces.
... This reinforces that nitrogen utilization is not exclusively determined by the level of protein in the diet and that increasing the energy available to the rumen microbes can reduce nitrogen excretion. It is well-established that urinary nitrogen is much more labile and susceptible to fast leaching and volatilization losses than fecal nitrogen (Powell et al., 2017). Reducing urinary nitrogen through diet manipulation represents an important way to reduce nitrogen excretion and mitigate the environmental impact . ...
The use of grazing systems for milk production is widely used globally because it is a lower-cost feeding system. However, under tropical conditions, the energy content of pastures became is a limitation to improve animal performance and efficiency while reducing the environmental impact. The objective of our study was to evaluate the impact of supplying different dietary sources of energy to lactating dairy cows grazing tropical pastures on the recovery of human-edible (HE) nutrients in milk and the environmental impact. Two experiments were conducted simultaneously. In experiment 1, forty early lactating dairy cows were used in a randomized block design. In experiment 2, four late-lactating rumen-cannulated dairy cows were used in a 4 × 4 Latin Square design. All cows had free access to pasture and treatments were applied individually as a concentrate supplement. Treatments were flint corn grain-processing method either as fine ground (FGC) or steam-flaked (SFC) associated with Ca salts of palm fatty acids supplementation either not supplemented (CON) or supplemented (CSPO). We observed that feeding cows with SFC markedly reduced urinary nitrogen excretion by 43%, and improved milk nitrogen efficiency by 17% when compared with FGC. Additionally, we also observed that feeding supplemental fat improved milk nitrogen efficiency by 17% compared with cows receiving CON diets. A tendency for decreased methane (CH 4 ) per unit of milk (−31%), CH 4 per unit of milk energy output (−29%), and CH 4 per unit of milk protein output (−31%) was observed when CSPO was fed compared with CON. Additionally, SFC diets increased HE recovery of indispensable amino acids by 7–9% when compared with FGC diets, whereas feeding supplemental fat improved HE recovery of indispensable amino acids by 17–19% compared with CON. Altogether, this study increased our understanding of how manipulating energy sources in the dairy cow diet under tropical grazing conditions can benefit HE nutrient recovery and reduce nutrient excretion.
... Optimizing animal nutrition is one approach to make ruminant production systems sustainable (Sotomayor-Ramirez et al., 2003;White et al., 2015). Powell et al. (2017) state that the type, amount, and quality of feeds offered to livestock greatly impact whole-farm N use efficiency. White et al. (2016) report that animal nutrition research has focused on improving energy and protein use efficiency; however, the potential environmental benefit of these research avenues has not been well investigated. ...
The aim of this study was to evaluate the nutrient fluxes for lactating cows in a pasture-based dairy system and the impact of a nutritional management strategy on the environmental performance indicators. Fourteen lactating cows were divided into two experimental groups with seven animals each. The nutritional managements were a diet containing 20% crude protein (Group 1) and a diet with adjusted protein (Group 2). The nutrient budget was calculated on a monthly basis for nitrogen, phosphorus, and potassium. The nutritional strategy of adjusted protein reduces the total surplus in the lactation period for nitrogen by 7.6% and for phosphorus by 6.3%. The total potassium surplus of the adjusted protein group was 8.5% higher. The average nitrogen use efficiency was 21% for group 1 and 22.7% for group 2. Phosphorus use efficiency ranged from 13.4 to 35% for group 1 and from 15.5 to 34% for group 2 and potassium average use efficiency was 14.2% for group 1 and 12.6% for group 2. Nutritional management reduced nitrogen and phosphorus surpluses as well as the values of the environmental performance indicator. Based on this, it is possible to improve the environmental efficiency of dairy systems through improved nutritional management.
... For example, N losses to waterways can cause aquatic eutrophication, N emissions as nitrous oxide can lead to stratospheric ozone depletion and to global warming, while ammonia deposition on sensitive ecosystems can result in terrestrial eutrophication and soil acidification (Asman et al., 1998;Hoekstra et al., 2020). While dairy cows have a large requirement for N, with dairy cow diets typically containing crude protein (CP) in a range between 160 and 180 g/kg dry matter (DM) (Webster, 2020), much of feed N consumed is in excess of what animals can utilize, and is excreted in feces and urine (Huhtanen et al., 2010;Powell et al., 2017). ...
... For example, N losses to waterways can cause aquatic eutrophication, N emissions as nitrous oxide can lead to stratospheric ozone depletion and to global warming, while ammonia deposition on sensitive ecosystems can result in terrestrial eutrophication and soil acidification (Asman et al., 1998;Hoekstra et al., 2020). While dairy cows have a large requirement for N, with dairy cow diets typically containing crude protein (CP) in a range between 160 and 180 g/kg dry matter (DM) (Webster, 2020), much of feed N consumed is in excess of what animals can utilize, and is excreted in feces and urine (Huhtanen et al., 2010;Powell et al., 2017). ...
The objective was to determine whether modern Holstein-origin dairy cows, when managed within grassland-based systems, partitioned more feed nitrogen (N) into milk and excreted less in manure, in comparison to an earlier population of Holstein-origin dairy cows. Data used were collated from total diet digestibility studies undertaken in Northern Ireland from 1990 to 2002 (old dataset, n = 538) and from 2005 to 2019 (new dataset, n = 476), respectively. An analysis of variance indicated that cows in the new dataset partitioned a significantly higher proportion of consumed N into milk and excreted a lower proportion in urine and total manure, compared to cows in the old dataset. A second analysis using the linear regression revealed that in comparison to the old dataset, the new dataset had a lower slope in the relationship between N intake and N excretion in urine or total manure, while a higher slope in the relationship between N intake and milk N output. A third analysis used the combined data from both datasets to examine if there was a relationship between experimental year and N utilization efficiency. Across the period from 1990 to 2019, urine N/N intake and manure N/N intake significantly decreased, while milk N/N intake increased. These results indicate that modern Holstein-origin dairy cows utilize consumed N more efficiently than earlier populations. Thus, N excretion is likely to be overestimated if models developed from the old data are used to predict N excretion for modern dairy herds. Therefore, the final part of analysis involved using the new dataset to develop prediction models for N excretion based on N intake and farm level data (milk yield, live weight and dietary N concentration). These updated models can be used to estimate N excretion from modern Holstein-origin dairy cows within grassland-based dairy systems.
... This is particularly true for areas with concentrated livestock production coupled with crop production. Improvement in regional NUE in these systems will only be achieved through better integration of livestock cropping systems with optimal recycling of manure nutrients (Powell et al. 2017). Long-term improvements in regional water quality will not likely be achieved until these larger scale issues in nutrient cycling are addressed. ...
... At a whole-farm scale, generally 15 to 55% of the total N input to the farm (including N fixation and N deposition) and 56 to 74% of the total P input to the farm is converted into edible and non-edible products (e.g. grain, forage, animals and milk) (Gerber et al., 2014;Powell et al., 2017). Most of the remaining nutrients are lost to the environment. ...
Assessing and improving the sustainability of dairy production is essential to secure future food production. Implementation of Beneficial Management Practices (BMP) can mitigate GHG emissions and nutrient losses and reduce the environmental impact of dairy production, but comprehensive, whole-farm studies that evaluate the efficacy of multiple BMPs to reduce multiple environmental impacts and that include an assessment of productivity and farm profitability, are scarce. We used a process-based model (IFSM) to assess the efficacy of (10+) individual BMPs to reduce the carbon (C) footprint expressed per unit of milk produced of two model dairy farms, a 1500 cow farm and a 150 cow farm, with farming practices representative for the Great Lakes region. In addition to the C footprint, we assessed the effect of BMP implementation on the reactive nitrogen (N) footprint and total phosphorus (P) losses (per unit of milk produced), as well as milk production and farm profitability. We evaluated individual farm-component specific BMPs, that is, 5 dietary manipulations, 3 (150 cow farm) or 4 (1500 cow farm) manure interventions, and 6 field interventions, as well as an integrated whole-farm mitigation strategy based on the best performing individual BMPs. Our results show that reductions in the C footprint expressed per unit of milk are greatest with individual manure management interventions (4–20% reduction) followed by dietary manipulations (0–12% reduction) for both farm types. Field management BMPs had a modest effect on reducing this footprint (0–3% reduction), but showed substantial potential to reduce the reactive N footprint (0–19% reduction) and P losses (1–47% reduction). We found that the whole-farm mitigation strategy can substantially reduce the C footprint, reactive N footprint and total P loss of both farms with predicted reductions of approximately 41%, 41% and 46% respectively, while increasing milk production and the net return per cow by approximately 11% and 27%. To contextualize IFSM predictions for the whole-farm mitigation, we compared components of IFSM predictions to those of three other process-based models (CNCPS, Manure-DNDC and EPIC). While we did observe differences in model predictions for individual flows (particularly P erosion and P leaching losses), with exception of the total P loss, the models generally predicted similar overall mitigation potentials. Overall, our analysis shows that an integrated set of BMPs can be implemented to reduce GHG emissions and nutrient losses of dairy farms in the Great Lakes region without sacrificing productivity or profit to the farmer.
In this paper, we propose to view the sustainability of dairy farming as nested within the sustainability of agriculture, a subset of the sustainability of food systems, which in turn could be construed as a subset of the national commitments of a country to achieve the Sustainable Development Goals (SDGs). Disciplinary, multidisciplinary, and interdisciplinary research are essential to study bio-physical system components and their interactions. However, when dairy farming is viewed as nested within broader societal systems, the inclusion of human elements calls for transdisciplinary research. Few of the 17 SDGs are left untouched by the livestock sector. Research should aim at identifying relevant farm-level metrics that are in alignment with any of the 231 indicators supporting the SDGs. We used two examples to illustrate the approach. In the first, SDG 13 (Climate Action) is used as a reminder that despite the current emphasis on reducing milk carbon footprint (kg CO2-e/kg milk), the contribution of the sector to Climate Action depends on reducing its annual emission (kg CO2-e/year; indicator 13.2.2). In the second example, indicator 2.4.1 (land use for sustainable agriculture) of SDG 2 (Zero Hunger) is used to illustrate the potential tradeoffs between Milk N/Intake N as a metric of nitrogen use efficiency at the cow level and metrics such as the input:output ratio of human-edible protein (Milk N/Intake of human-edible N) that prioritize the use of human-inedible feed in dairy rations as a way to enhance efficiency and circularity at the food system level.
Viruses need a host for replication. In a hectare grassland, for example, a huge amount of diverse cells, majorly microbial cells are present, in which viral inserts replicate either lysogenically with the host genome or lytically after reprogramming the host metabolism towards virus particle production. A third replication mode is “chronic extrusion”. Thereby single stranded (ss) viral DNA is channelled through the cytoplasmic membrane into the surrounding environment and double stranded DNA (ds) reintegrates in new host genomes. During lytic virus replication the host cell bursts. The produced virus particles, now termed virions, and the cell nutrients are released and potential pro- and eukaryotic hosts are attracted. In a nutrient enriched environment virions find easier a new genome for reintegrating by using their inherent infectivity and autoinduced quorum-sensing. After having entered a new host lysogenic, lytic replication switching starts. During “chronic extrusion” and lytic replication cycles set free virions can absorb epigenetic information, which then may be spread by horizontal gene transfers. Lysogenic, lytic replication switchings, termed viral shunts, are temperate. Host cell multiplication regulator, carefully controlled in nature. Assumed 1% of the wealth of host cells in a hectare grassland burst lytic virus replication mediated a significant influence on the gross primary production (GPP) is inevitable. Epigenetic genetic information exchanges may improve host’s health and correspondingly the focus of this chapter lies on virus mediated nutrient side drain estimates, calculated in their importance for a hectare grassland.
In recent decades, the rate of milk production per unit land area and per cow has increased with the intensification of the dairy system. The possible environmental risks arising from nutrients surpluses, such as nitrogen (N), are often evaluated using the N balance approach. In Hokkaido, the biggest dairy farming area in Japan, many dairy farms have started introducing a new dairy farming system called the total mixed ration (TMR) and biogas system. Feed and manure are managed at a community scale in these systems while each farm focuses primarily on milking cows. Thus, calculating the N balance for this system is complicated. Therefore, this study aimed to evaluate the N surplus and use efficiency (NUE), focusing mainly on the community-based dairy farming system, as described above. We investigated twenty dairy farms comprising a TMR centre (TMR-based farms) and nineteen conventional dairy farms (conventional farms). The Hokkaido dairy farms had a smaller N surplus and higher NUE than farms in other countries. The whole farm N surplus and NUE ranged from −163 to 701 kg N ha ⁻¹ and from 20% to 171% with median values of 40.5 kg N ha ⁻¹ and 69.5%, respectively. One of the possible reasons for the smaller N surplus and higher NUE is a lower stocking rate (averaged 1.3 cows ha ⁻¹ ) on Hokkaido dairy farms. There were strong relationships between feed N and N surplus because the studied dairy farms depended on purchased feed. In the comparison between the TMR centre and conventional dairy farms, the milk production level per cow and stocking rate tended to increase, and variations between farms decreased on the TMR-based farms. Increasing the amount of home-grown feed with pasture management is essential to decreasing N surplus for the new dairy farming systems.
A resilient US dairy industry will be underpinned by forage and crop production systems that are economically, environmentally, and socially sustainable. Land use for production of perennial and annual forages and grains for dairy cattle must evolve in response to multiple food security and environmental sustainability issues. These include increasing global populations; higher incomes and demand for dairy and other animal products; climate change with associated temperature and moisture changes; necessary reductions in carbon and water footprints; maintenance of soil quality and soil nutrient concerns; and competition for land. Likewise, maintaining producer profitability and utilizing practices accepted by consumers and society generally must also be considered. Predicted changes in climate and water availability will likely challenge current feed and dairy production systems and their national spatial distribution, particularly the western migration of dairy production in the late 20th century. To maintain and stabilize profitability while reducing carbon footprint, particularly reductions in methane emission and enhancements in soil carbon sequestration, dairy production will need to capitalize on genetic and management innovations that enhance forage and grain production and nutritive value. Improved regional and on-farm integration of feed production and manure utilization is needed to reduce environmental nitrogen and phosphorus losses and mitigate greenhouse gas emissions. Resilient and flexible feed production strategies are needed to address each of these challenges and opportunities to ensure profitable feeding of dairy cattle and a sustainable dairy industry.
Animal production is a significant source of greenhouse gas (GHG) emissions worldwide. Depending on the accounting approaches and scope of emissions covered, estimates by various sources (IPCC, FAO, EPA or others) place livestock contribution to global anthropogenic GHG emissions at between 7 and 18 percent. The current analysis was conducted to evaluate the potential of nutritional, manure and animal husbandry practices for mitigating methane (CH4) and nitrous oxide (N2O) – i.e. non-carbon dioxide (non-CO2) – GHG emissions from livestock production. These practices were categorized into enteric CH4, manure management and animal husbandry mitigation practices. Emphasis was placed on enteric CH4 mitigation
practices for ruminant animals (only in vivo studies were considered) and manure mitigation practices for both ruminant and monogastric species. Over 900 references were reviewed; and simulation and life cycle assessment analyses were generally excluded. In evaluating mitigation practices, the use of proper units is critical. Expressing enteric CH4 energy production on gross energy intake basis, for example, does not accurately reflect the potential impact of diet quality and composition. Therefore, it is noted that GHG emissions should be expressed on a digestible energy intake basis or per unit of animal product
(i.e. GHG emission intensity), because this reflects most accurately the effect of a given mitigation practice on feed intake and the efficiency of animal production.
Enteric CH4 mitigation practices
Increasing forage digestibility and digestible forage intake will generally reduce GHG emissions from rumen fermentation (and stored manure), when scaled per unit of animal product, and are highly-recommended mitigation practices. For example, enteric CH4 emissions may be reduced when corn silage replaces grass silage in the diet. Legume silages may also have an advantage over grass silage due to their lower fibre content and the additional benefit of replacing inorganic nitrogen fertilizer. Effective silage preservation will improve forage quality on the farm and reduce GHG emission intensity. Introduction of legumes into grass pastures in warm climate regions may offer a mitigation opportunity, although more research is needed to address the associated agronomic challenges and comparative N2O emissions with equivalent production levels from nitrogen fertilizer. Dietary lipids are effective in reducing enteric CH4 emissions, but the applicability of this practice will depend on its cost and its effects on feed intake, production and milk composition. High-oil by-product feeds, such as distiller’s grains, may offer an economically feasible
alternative to oil supplementation as a mitigation practice, although their higher fibre content may have an opposite effect on enteric CH4, depending on basal diet composition. Inclusion of concentrate feeds in the diet of ruminants will likely decrease enteric CH4 emissions per unit of animal product, particularly when above 40 percent of dry matter intake. The effect may depend on type of ‘concentrate’ inclusion rate, production response, impact on fibre digestibility, level of nutrition, composition of the basal diet and feed processing. Supplementation with small amounts of concentrate feed is expected to increase animal
productivity and decrease GHG emission intensity when added to all-forage diets. However, concentrate supplementation should not substitute high-quality forage. Processing of grain to increase its digestibility is likely to reduce enteric CH4 emission intensity. Nevertheless, caution should be exercised so that concentrate supplementation and processing does not compromise digestibility of dietary fibre. In many parts of the world, concentrate inclusion may not be an economically feasible mitigation option. In these situations improving the nutritive value of low-quality feeds in ruminant diets can have a considerable benefit on herd
productivity, while keeping the herd CH4 output constant or even decreasing it. Chemical treatment of low-quality feeds, strategic supplementation of the diet, ration balancing and crop selection for straw quality are effective mitigation strategies, but there has been little adoption of these technologies. Nitrates show promise as enteric CH4 mitigation agents, particularly in low-protein diets that can benefit from nitrogen supplementation, but more studies are needed to fully understand their impact on whole-farm GHG emissions, animal productivity and animal health. Adaptation to these compounds is critical and toxicity may be an issue. Through their effect on feed efficiency, ionophores are likely to have a moderate CH4 mitigating effect in ruminants fed high-grain or grain-forage diets. However, regulations restrict the availability of
this mitigation option in many countries. In ruminants on pasture, the effect of ionophores is not sufficiently consistent for this option to be recommended as a mitigation strategy. Tannins may also reduce enteric CH4 emissions, although intake and milk production may be compromised. Further, the agronomic characteristics of tanniferous forages must be considered when they are discussed as a GHG mitigation option. There is not sufficient evidence that other plant-derived bioactive compounds, such as essential oils, have a CH4-mitigating effect. Some direct-fed microbials, such as yeast-based products, might have a moderate
CH4-mitigating effect through increasing animal productivity and feed efficiency, but the effect is expected to be inconsistent. Vaccines against rumen archaea may offer mitigation opportunities in the future, although the extent of CH4 reduction appears small, and adaptation and persistence of the effect is unknown.
Manure management mitigation practices
Diet can have a significant impact on manure (faeces and urine) chemistry and therefore on GHG emissions during storage and following land application. Manure storage may be required when animals are housed indoors or on feedlots, but a high proportion of ruminants are grazed on pastures or rangeland, where CH4 emissions from their excreta is very low and N2O losses from urine can be substantial. Decreased digestibility of dietary nutrients is expected to increase fermentable organic matter concentration in manure, which may
increase manure CH4 emissions. Feeding protein close to animal requirements, including varying dietary protein concentration with stage of lactation or growth, is recommended as an effective manure ammonia and N2O emission mitigation practice. Low-protein diets for ruminants should be balanced for rumen-degradable protein so that microbial protein synthesis and fibre degradability are not impaired. Decreasing total dietary protein and supplementing the diet with synthetic amino acids is an effective ammonia and N2O mitigation strategy for non-ruminants. Diets for all species should be balanced for amino acids to avoid
feed intake depression and decreased animal productivity. Restricting grazing when conditions are most favourable for N2O formation, achieving a more uniform distribution of urine on soil and optimizing fertilizer application are possible N2O mitigation options for ruminants on pasture. Forages with higher sugar content (high-sugar grasses or forage harvested in the afternoon when its sugar content is higher) may reduce urinary nitrogen excretion, ammonia volatilization and perhaps N2O emission from manure applied to soil, but more research is needed to support this hypothesis. Cover cropping can increase plant nitrogen uptake and
decrease accumulation of nitrate, and thus reduce soil N2O emissions, although the results have not been conclusive. Urease and nitrification inhibitors are promising options to reduce N2O emissions from intensive livestock production systems, but can be costly to apply and result in limited benefits to the producer. Overall, housing, type of manure collection and storage system, separation of solids and liquid and their processing can all have a significant impact on ammonia and GHG emissions from animal facilities. Most mitigation options for GHG emissions from stored manure, such as reducing the time of manure storage, aeration, and stacking, are generally aimed at decreasing the time allowed for microbial fermentation processes to occur before land application. These mitigation practices are effective, but their economic feasibility is uncertain.
Semi-permeable covers are valuable for reducing ammonia, CH4 and odour emissions at storage, but are likely to increase N2O emissions when effluents are spread on pasture or crops. Impermeable membranes, such as oil layers and sealed plastic covers, are effective in reducing gaseous emissions but are not very practical. Combusting accumulated CH4 to produce electricity or heat is recommended. Acidification (in areas where soil acidity is not an issue) and cooling are further effective methods for reducing ammonia and CH4 emissions from stored manure. Composting can effectively reduce CH4 but can have a variable effect
on N2O emissions and increases ammonia and total nitrogen losses. Anaerobic digesters are a recommended mitigation strategy for CH4 generate renewable energy, and provide sanitation opportunities for developing countries, but their effect on N2O emissions is unclear. Management of digestion systems is important to prevent them from becoming net emitters of GHG. Some systems require high initial capital investments and, as a result, their adoption may occur only when economic incentives are offered. Anaerobic digestion systems are not recommended for geographic locations with average temperatures below 15 °C without supplemental heat and temperature control. Lowering nitrogen concentration in manure, preventing anaerobic conditions and reducing the input of degradable manure carbon are effective strategies for reducing GHG emissions from manure applied to soil. Separation of manure solids and anaerobic degradation
pre-treatments can mitigate CH4 emission from subsurface-applied manure, which may otherwise be greater than that from surface-applied manure. Timing of manure application (e.g. to match crop nutrient demands, avoiding application before rain) and maintaining soil pH above 6.5 may also effectively decrease N2O emissions.
Animal husbandry mitigation practices
Increasing animal productivity can be a very effective strategy for reducing GHG emissions per unit of livestock product. For example, improving the genetic potential of animals through planned cross-breeding or selection within breeds, and achieving this genetic poten tial through proper nutrition and improvements in reproductive efficiency, animal health and reproductive lifespan are effective and recommended approaches for improving animal productivity and reducing GHG emission intensity. Reduction of herd size would increase
feed availability and productivity of individual animals and the total herd, thus lowering CH4 emission intensity. Residual feed intake may be an appealing tool for screening animals that are low CH4 emitters, but currently there is insufficient evidence that low residual feed intake animals have a lower CH4 yield per unit of feed intake or animal product. However, selection for feed efficiency will yield animals with lower GHG emission intensity. Breed difference in feed efficiency should also be considered as a mitigation option, although insufficient data are currently available on this subject. Reducing age at slaughter of finished cattle and the number of days that animals are on feed in the feedlot by improving nutrition and genetics can also have a significant impact on GHG emissions in beef and other meat animal production systems.
Improved animal health and reduced mortality and morbidity are expected to increase herd productivity and reduce GHG emission intensity in all livestock production systems. Pursuing a suite of intensive and extensive reproductive management technologies provides a significant opportunity to reduce GHG emissions. Recommended approaches will differ by region and species, but will target increasing conception rates in dairy, beef and buffalo, increasing fecundity in swine and small ruminants, and reducing embryo wastage in all
species. The result will be fewer replacement animals, fewer males required where artificial insemination is adopted, longer productive life and greater productivity per breeding animal.
Conclusions
Overall, improving forage quality and the overall efficiency of dietary nutrient use is an effective way of decreasing GHG emissions per unit of animal product. Several feed supplements have a potential to reduce enteric CH4 emission from ruminants, although their long-term effect has not been well-established and some are toxic or may not be economically viable in developing countries. Several manure management practices have a significant potential for decreasing GHG emissions from manure storage and after
application or deposition on soil. Interactions among individual components of livestock production systems are very complex, but must be considered when recommending GHG mitigation practices. One practice may successfully mitigate enteric CH4 emission, but increase fermentable substrate for increased GHG emissions from stored or landapplied manure. Some mitigation practices are synergistic and are expected to decrease
both enteric and manure GHG emissions (for example, improved animal health and animal productivity). Optimizing animal productivity can be a very successful strategy for mitigating GHG emissions from the livestock sector in both developed and developing countries.
Ruminants play a key role in human food production by converting fiber-rich plant resources that humans cannot (or choose not to) consume into high-quality food that humans can eat. However, this conversion causes unavoidable losses of nitrogen (N) in feces and urine from ruminants that may become an environmental burden, in particular nitrate (NO3-) leaching, ammonia (NH3) volatilization and nitrous oxide (N2O) emissions. The aim of this paper is to identify the maximal theoretical N efficiency at the animal level, and the challenges and opportunities to achieve this maximal N efficiency. This is done via striving for the lowest possible N excretion in urine and feces, and for purposes here, with a focus on dairy cattle. Inevitable N losses in dairy cattle include losses associated with urinary excretion of urea synthesized from ammonia produced in the rumen; undigested microbial protein excreted in feces; microbial nucleic acids synthesized in the rumen and excreted mainly in urine; fecal and urinary excretion resulting from endogenous secretions; and urinary excretion related to maintenance and milk protein synthesis. The theoretical upper limit of N use efficiency in a dairy cow producing 40 kg fat and protein corrected milk/d is 0.43. Higher efficiencies may be achieved, but these require major inputs of human edible resources. The present analysis demonstrates there is little or no scope to reduce N losses related to microbial nucleic acid synthesis, recycling of N to the rumen, intestinal digestion of microbial protein, and animal maintenance requirements. Strategies to reduce N losses and improve N efficiency should focus on an optimal supply of rumen degradable N and optimal efficiency of utilization of absorbed amino acids for milk protein synthesis. To improve N efficiency, integration between protein and energy metabolism is essential, and energy and protein should be considered together rather than as two distinct entities. A major challenge in strategies to optimize high-fiber diets for high milk N efficiency will be to avoid increases in enteric methane production associated with these dietary strategies.
In dairy production systems, tradeoffs can occur between fertilizer N applications and crop N use, feed N consumption and manure N excretion, and environmental impacts. This paper examines (i) how stocking rates affect N imports and management on dairy farms, N use efficiency (NUE; i.e., the amount of applied N incorporated into product N), and N loss; (ii) how reductions in fertilizer N and feed N may affect crop and milk production, NUE, and N loss; and (iii) why tradeoffs in N use outcomes should be considered when attempting to enhance overall NUE and reduce N loss. The Integrated Farm Simulation Model simulations of two representative dairy farm types and analyses of regional studies, long-term field experiments, and cow nutrition trials were used to demonstrate that (i) stocking rate affects cropping patterns, fertilizer and feed imports, and N loss; (ii) although fertilizer N reductions of 20 kg N ha may reduce slightly the crude protein (CP) content of corn silage (which would require purchase of additional CP supplements), this practice should not affect long-term corn yield but would reduce nitrate (NO) and nitrous oxide (NO) losses by 13 to 38%; (iii) dietary CP could be reduced on many dairy farms, which would not affect milk production but would reduce ammonia (NH) and NO emissions by 15 to 43%; and (iv) greater recognition of the tradeoffs in N use and N loss are needed to provide a better understanding of the potentials to enhance overall NUE and reduce environmental N loss from dairy production systems.
Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.
Urinary urea N (UUN) is the principal nitrogen (N) source controlling emissions of ammonia (NH) and nitrous oxide (NO) from dairy manure. The objectives of this study were (i) to study the integrative nature of dietary crude protein (CP) management, secretion of milk urea N (MUN), excretion of UUN, and N emissions from dairy production systems; (ii) to evaluate how associative changes in dietary CP, MUN, and UUN affect atmospheric N emissions from dairy farms; and (iii) to discuss some of the challenges and opportunities to an expanded use of MUN to enhance dietary CP use and decrease UUN excretion and N emissions from dairy farms. Milk urea N records of 37,889 cows in 197 herds in Wisconsin revealed that approximately one half of tested cows were likely consuming dietary CP in excess of requirement. Farm simulations were used to quantify the effect of dietary CP on whole-farm N emissions. At a statewide average MUN of 12.5 mg dL, 48 to 87% of UUN was emitted as NH, with the lowest loss from pasture-based farms and the greatest loss from tie-stall farms. Each 1 mg dL decrease of MUN (range, 16-10 mg dL) provided an associated daily decrease in UUN of 16.6 g per cow, which decreased NH and NO emissions from manure by 7 to 12%. Although more site-specific information is required on herd MUN-UUN relationships and more a reliable interpretation of MUN assay results is needed, monitoring of MUN may be used to enhance dietary CP use and to reduce UUN excretion and N emissions from Wisconsin dairy farms.
Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.
2011. Review: Ammonia emissions from dairy farms and beef feedlots. Can. J. Anim. Sci. 91: 1Á35. Ammonia emitted from animal feeding operations is an environmental and human health hazard, contributing to eutrophication of surface waters and nitrate contamination of ground waters, soil acidity, and fine particulate matter formation. It may also contribute to global warming through nitrous oxide formation. Along with these societal concerns, ammonia emission is a net loss of manure fertilizer value to the producer. A significant portion of cattle manure nitrogen, primarily from urinary urea, is converted to ammonium and eventually lost to the atmosphere as ammonia. Determining ammonia emissions from cattle operations is complicated by the multifaceted nature of the factors regulating ammonia volatilization, such as manure management, ambient temperature, wind speed, and manure composition and pH. Approaches to quantify ammonia emissions include micrometeorological methods, mass balance accounting and enclosures. Each method has its advantages, disadvantages and appropriate application. It is also of interest to determine the ammonia emitting potential of manure (AEP) independent of environmental factors. The ratio of nitrogen to non-volatile minerals (phosphorus, potassium, ash) or nitrogen isotopes ratio in manure has been suggested as a useful indicator of AEP. Existing data on ammonia emission factors and flux rates are extremely variable. For dairy farms, emission factors from 0.82 to 250 g ammonia per cow per day have been reported, with an average of 59 g per cow per day (n 031). Ammonia flux rates for dairy farms averaged 1.03 g m (2 h (1 (n 024). Ammonia losses are significantly greater from beef feedlots, where emission factors average 119 g per animal per day (n 09) with values as high as 280 g per animal per day. Ammonia flux rate for beef feedlots averaged 0.174 g m (2 h (1 (n 012). Using nitrogen mass balance approaches, daily ammonia nitrogen losses of 25 to 50% of the nitrogen excreted in manure have been estimated for dairy cows and feedlot cattle. Practices to mitigate ammonia emissions include reducing excreted N (particularly urinary N), acidifying ammonia sources, or binding ammonium to a substrate. Reducing crude protein concentration in cattle diets and ruminal protein degradability are powerful tools for reducing N excretion, AEP, and whole-farm ammonia emissions. Reducing dietary protein can also benefit the producer by reducing feed cost. These interventions, however, have to be balanced with the risk of lost production. Manure treatment techniques that reduce volatile N species (e.g., urease inhibition, pH reduction, nitrification-denitrification) are also effective for mitigating ammonia emissions. Another option for reducing ammonia emissions is capture and treatment of released ammonia. Examples in the latter category include biofilters, permeable and impermeable covers, and manure incorporation into the soil for crop or pasture production. Process-level simulation of ammonia formation and emission provides a useful tool for estimating emissions over a wide range of production practices and evaluating the potential benefits of mitigation strategies. Reducing ammonia emissions from dairy and beef cattle operations is critical to achieving environmentally sustainable animal production that will benefit producers and society at large.
Nitrous oxide (N2O) emissions account for similar to 10% of global greenhouse gas (GHG) emissions, with most of these emissions (similar to 90%) deriving from agricultural practices. Animal agriculture potentially contributes up to 50% of total agricultural N2O emissions. In intensive animal agriculture, high N2O emission rates generally coincide with anaerobic soil conditions and high soil NO3-, primarily from animal urine patches. This paper provides an overview of animal, feed-based and soil or management abatement technologies for ruminant animal agriculture targeted at reducing the size of the soil NO3- pool or improving soil aeration. Direct measurements of N2O emissions from potential animal and feed-based intervention technologies are scarce. However, studies have shown that they have the potential to reduce urinary N excretion by 3-60% and thus reduce associated N2O emissions. Research on the effect of soil and water management interventions is generally further advanced and N2O reduction potentials of up to 90% have been measured in some instances. Of the currently available technologies, nitrification inhibitors, managing animal diets and fertiliser management show the best potential for reducing emissions in the short-term. However, strategies should always be evaluated in a whole-system context, to ensure that reductions in one part of the system do not stimulate higher emissions elsewhere. Current technologies reviewed here could deliver up to 50% reduction from an animal housing system, but only up to 15% from a grazing-based system. However, given that enteric methane emissions form the majority of emissions from grazing systems, a 15% abatement of N2O is likely to translate to a 2-4% decrease in total GHG emissions at a farm scale. Clearly, further research is needed to develop technologies for improving N cycling and reducing N2O emissions from grazing-based animal production systems.
Indirect estimates of manure N availability to crops are highly variable. We developed two methods that label dairy manure N components with the stable isotope 15N for direct measurement of manure N availability to crops. The forage method involved the labeling then feeding of 15N-enriched forage to dairy cows (Bos taurus) to label urine N, fecal endogenous N, and fecal undigested feed N. The urea method involved the direct feeding of 15N-enriched urea to label urine N and fecal endogenous N. Manure from each enrichment method was applied to a Plano silt loam (fine-silty, mixed, mesic, Typic Argiudolls) using field plots in 1999 and 2000; corn (Zea mays L.) was grown for 2 yr after each application. No significant differences were observed in manure 15N recoveries in corn, soil inorganic N, or soil total N due to manure application year or manure enrichment method. Corn took up 14 to 16% of manure 15N the first year and 4 to 8% the second year after application. Most 15N recovery in soil inorganic and total N was found in the upper 30 cm of soil, indicating little downward movement of applied manure 15N. On average, 68% of applied manure 15N was accounted for, either in crop uptake (21%) or in the soil (47%). The less laborious and less costly urea enrichment method may be adequate for short-term (2 yr or less, the range of this study) manure-soil-crop-N cycling studies. Longer-term studies may need to include fecal undigested feed 15N derived from the forage enrichment method.
The objective of this study was to determine the effects of replacing alfalfa silage (AS) with corn silage (CS) in dairy cow total mixed rations (TMR) on enteric CH4 emissions, ruminal fermentation characteristics, apparent total-tract digestibility, N balance, and milk production. Nine ruminally cannulated lactating cows were used in a replicated 3 × 3 Latin square design (32-d period) and fed (ad libitum) a TMR [forage:concentrate ratio of 60:40; dry matter (DM) basis], with the forage portion consisting of either alfalfa silage (0% CS; 56.4% AS in the TMR), a 50:50 mixture of both silages (50% CS; 28.2% AS and 28.2% CS in the TMR), or corn silage (100% CS; 56.4% CS in the TMR). Increasing the CS proportion (i.e., at the expense of AS) in the diet was achieved by decreasing the corn grain proportion and increasing that of soybean meal. Intake of DM and milk yield increased quadratically, whereas DM digestibility increased linearly as the proportion of CS increased in the diet. Increasing the dietary CS proportion resulted in changes (i.e., lower ruminal pH and acetate:propionate ratio, reduced fiber digestibility, decreased protozoa numbers, and lower milk fat and higher milk protein contents) typical of those observed when cows are fed high-starch diets. A quadratic response in daily CH4 emissions was observed in response to increasing the proportion of CS in the diet (440, 483, and 434 g/d for 0% CS, 50% CS, and 100% CS, respectively). Methane production adjusted for intake of DM, and gross or digestible energy was unaffected in cows fed the 50% CS diet, but decreased in cows fed the 100% CS diet (i.e., quadratic effect). Increasing the CS proportion in the diet at the expense of AS improved N utilization, as reflected by the decreases in ruminal NH3 concentration and manure N excretion, suggesting low potential NH3 and N2O emissions. Results from this study, suggest that total replacement of AS with CS in dairy cow diets offers a means of decreasing CH4 output and N losses. However, the reduction in fiber degradation and the resulting increase in volatile solids content of the manure may lead to increased CH4 emissions from manure storage.
Holstein cows housed in a modified tie-stall barn were used to determine the effect of feeding diets with different forage-to-concentrate ratios (F:C) on performance and emission of CH(4), CO(2) and manure NH(3)-N. Eight multiparous cows (means ± standard deviation): 620 ± 68 kg of body weight; 52 ± 34 d in milk and 8 primiparous cows (546 ± 38 kg of body weight; 93 ± 39 d in milk) were randomly assigned to 1 of 4 air-flow controlled chambers, constructed to fit 4 cows each. Chambers were assigned to dietary treatment sequences in a single 4 × 4 Latin square design. Dietary treatments, fed as 16.2% crude protein total mixed rations included the following F:C ratio: 47:53, 54:46, 61:39, and 68:32 [diet dry matter (DM) basis]. Forage consisted of alfalfa silage and corn silage in a 1:1 ratio. Cow performance and emission data were measured on the last 7 d and the last 4 d, respectively of each 21-d period. Air samples entering and exiting each chamber were analyzed with a photo-acoustic field gas monitor. In a companion study, fermentation pattern was studied in 8 rumen-cannulated cows. Increasing F:C ratio in the diet had no effect on DM intake (21.1 ± 1.5 kg/d), energy-corrected milk (ECM, 37.4 ± 2.2 kg/d), ECM/DM intake (1.81 ± 0.18), yield of milk fat, and manure excretion and composition; however, it increased milk fat content linearly by 7% and decreased linearly true protein, lactose, and solids-not-fat content (by 4, 1, and 2%, respectively) and yield (by 10, 6, and 6%, respectively), and milk N-to-N intake ratio. On average 93% of the N consumed by the cows in the chambers was accounted for as milk N, manure N, or emitted NH(3)-N. Increasing the F:C ratio also increased ruminal pH linearly and affected concentrations of butyrate and isovalerate quadratically. Increasing the F:C ratio from 47:53 to 68:32 increased CH(4) emission from 538 to 648 g/cow per day, but had no effect on manure NH(3)-N emission (14.1 ± 3.9 g/cow per day) and CO(2) emission (18,325 ± 2,241 g/cow per day). In this trial, CH(4) emission remained constant per unit of neutral detergent fiber intake (1g of CH(4) was emitted for every 10.3g of neutral detergent fiber consumed by the cow), but increased from 14.4 to 18.0 g/kg of ECM when the percentage of forage in the diet increased from 47 to 68%. Although the pattern of emission within a day was distinct for each gas, emissions were higher between morning feeding (0930 h) and afternoon milking (1600 h) than later in the day. Altering the level of forage within a practical range and rebalancing dietary crude protein with common feeds of the Midwest of the United States had no effects on manure NH(3)-N emission but altered CH(4) emission.
Estimates of the availability of dairy manure nutrients to crops rely on indirect measurements and can vary greatly. More accurate estimates of manure nutrient availability are needed to improve manure management. The objective of this study was to enrich dairy feces and urine in (15)N to study nutrient flow in the feed-animal-manure-soil and crop-environment continuum. Ammonium sulfate (12.3 or 10 atom % (15)N)) was applied to soil to enrich alfalfa (Medicago sativa L.) and corn (Zea mays L.) plants during growth. Alfalfa hay contained from 2.386 to 3.980 atom % (15)N in three harvests and corn silage contained 8.162 atom % (15)N. A feed mixture containing 55% alfalfa hay and 45% corn silage (4.026 atom % (15)N) was fed to two mature nonlactating cows (Bos taurus) for 36 h. The pattern of (15)N excretion in urine and feces was similar for both cows. The (15)N appeared in urine by 8 h and in feces by 24 h, and peaked by 30 h in urine (1.642 atom % (15)N) and by 54 h in feces (2.341 atom % (15)N). Enrichment approached basal levels at 132 h after initial feeding for both urine and feces. Of the total (15)N fed, 60% was recovered: 31% from urine and 29% from feces. Approximately 60 to 70% of the total N excreted in dairy feces was endogenous N and 30 to 40% was undigested feed N. Combining feces excreted during the 16- to 122-h period after initial feeding of (15)N-enriched feed would produce feces having uniformly labeled N components. The various (15)N-enrichment levels of urine and feces collected during different times after feeding offer possibilities for studying differential (15)N use in short- and long-term nutrient cycling studies.
Although integrated crop-livestock systems have been employed globally for millennia, in the past century, farmers in North America have tended toward increased specialization. There is renewed interest in reintegrating crops and livestock because of concerns about natural resource degradation, the profitability and stability of farm income, long-term sustainability, and increasing regulation of concentrated animal feeding operations. Integrated crop-livestock systems could foster diverse cropping systems, including the use of perennial and legume forages, which could be grown in selected areas of the landscape to achieve multiple environmental benefits. Integrated systems inherently would utilize animal manure, which enhances soil tilth, fertility, and C sequestration. Integration of crops and livestock could occur within a farm or among farms. Both scales of integration rely on farmers' knowledge, motivation, and resources. Despite the numerous benefits that could accrue if farms moved toward on-farm or among-farm integration of crops and livestock, the complexity of such systems could constrain adoption. However, farmers should expect that adoption of integrated crop-livestock systems would enhance both profitability and environmental sustainability of their farms and communities. The combination of system complexity and potential for public benefit justify the establishment of a new national or international research initiative to overcome constraints and move North American agriculture toward greater profitability and sustainability.
Current estimates of dairy manure nitrogen availability to crops are based on indirect measures and vary greatly. The objective of this study was to differentially label dairy manure N components with the stable isotope 15N for direct measurement of manure N cycling in soils and availability to crops. Dairy urine and fecal N components (microbial and undigested feed N) were differentially labeled by feeding either 15N-enriched forage or urea to mature dry dairy cows (Bos taurus). Nitrogen-15-enriched ammonium sulfate was used to label alfalfa (Medicago sativa L.) hay and corn (Zea mays L.) silage. These 15N-enriched forages or either single or multiple doses of 15N-enriched urea were fed for 2 to 3 d, and feces and urine were collected separately for 8 d after the initiation of 15N feeding. For both labeling techniques, 15N appeared first in urine followed by fecal microbial and undigested feed N. For the forage method, the proportionate combination of feces excreted before and after peak 15N excretion levels would achieve uniform labeling of fecal N components. For the urea method, no undigested feed N in feces was labeled since 15N-enriched forage N was not fed. The choice of which labeling method to use depends on the intended use of labeled manure. Manure enriched using the forage method and high levels of manure 15N enrichments should be used for long-term manure N cycling studies. Manure enriched using the urea method and lower 15N enrichments could be used in shorter-term studies.
Availability of manure nitrogen (N) to crops is mitigated by many factors including manure type and composition. Whereas relationships between dairy diets, milk production, manure N excretion, and urine N losses as ammonia have been documented, very little information exists on how diets impact fecal carbon (C), N content, and partitioning, and how these factors impact fecal N mineralization and plant N uptake after application to soil. Feces from 24 to 63 dairy cows (Bos taurus) fed 14 typical diets were incubated aerobically in a sandy loam and two silt loam soils, and soil inorganic N (IN) was determined periodically during a 365-d period. Feces from 12 of the 14 diets were applied to the same soils and oat (Avena sativa L.), sorghum (Sorghum bicolor L. Moench), and sorghum ratoon dry matter (DM) and N uptake were determined over a 155-d period. Feces from cows fed alfalfa (Medicago sativa L.) silage (AS)-based diets generally lead to higher soil IN levels than soils amended with feces from corn (Zea mays L.) silage (CS)-based diets, especially in soils amended with feces from CS-low crude protein (LCP) diets; feces from AS-based diets increased plant DM and N uptake; after application to a silt loam, feces from high crude protein (HCP) diets resulted in greater soil IN levels than feces from LCP diets; and feces from LCP diets did not impact soil IN but decreased plant DM and N uptake. Carbon to N (C/N) ratios of applied feces were found to be significant predictors of plant DM and N uptake. There appears to be a range of dietary options that satisfy nutritional requirements of high-producing dairy cows and produce feces having differential effects on soil N mineralization and plant N uptake after application to soil.
Data sets from North American (NA, 739 diets) and North European (NE, 998 diets) feeding trials with dairy cows were evaluated to investigate the effects of dietary crude protein (CP) intake and ruminal degradability on milk protein yield (MPY) and efficiency of N utilization for milk protein synthesis (MNE; milk N / N intake) in dairy cows. The NA diets were based on corn silage, alfalfa silage and hay, corn and barley grains, and soybean meal. The NE diets were based on grass silage, barley and oats grains, and soybean and rapeseed meals. Diets were evaluated for rumen-degradable and undegradable protein (RDP and RUP, respectively) concentrations according to NRC (2001). A mixed model regression analysis with random study effect was used to evaluate relationships between dietary CP concentration and degradability and MPY and MNE. In both data sets, CP intake alone predicted MPY reasonably well. Addition of CP degradability to the models slightly improved prediction. Models based on metabolizable protein (MP) intake predicted MPY better than the CP or the CP-CP degradability models. The best prediction models were based on total digestible nutrients (TDN) and CP intakes. Similar to the MPY models, inclusion of CP degradability in the CP (intake or concentration) models only slightly improved prediction of MNE in both data sets. Concentration of dietary CP was a better predictor of MNE than CP intake. Compared with the CP models, prediction of MNE was improved by inclusion of TDN intake or concentration. Milk yield alone was a poor predictor of MNE. The models developed from one data set were validated using the other data set. The MNE models based on TDN and CP intake performed well as indicated by small mean and slope bias. This meta-analysis demonstrated that CP concentration is the most important dietary factor influencing MNE. Ruminal CP degradability as predicted by NRC (2001) does not appear to be a significant factor in predicting MPY or MNE. Data also indicated that increasing milk yield will increase MNE provided that dietary CP concentration is not increased, but the effect is considerably smaller than the effect of reducing CP intake.
Forage chemistry can affect intake, digestion, milk production, and manure excretion. Although information is available on the effects of forage protein-binding polyphenols on small ruminant production and manure excretion, little information is available for dairy cattle. The objective of this study was to compare fecal and urinary N excretion of diets formulated with alfalfa (Medicago sativa L.) silage versus condensed tannin-containing birdsfoot trefoil (Lotus corniculatus) or o-quinone-containing red clover (Trifolium pratense L.) silages. Significantly higher concentrations of N were excreted in urine by lactating Holstein dairy cows fed red clover and low-tannin birdsfoot trefoil (8.2 g/L) than by cows fed high-tannin birdsfoot trefoil or alfalfa (7.1 g/L). Fecal N concentrations were similar (33.6 g/kg) among all diets. Dairy cows fed red clover had lower rates of urinary N excretion (5.0 g/h) compared with other forages (6.6 g/h). Fecal N excretion rates were lowest for red clover (4.1 g/h), intermediate for alfalfa (5.8 g/h), and greatest for cows fed high- and low-tannin birdsfoot trefoil (6.4 g/h). The ratio of fecal N to urinary N was highest for high-tannin trefoil, lowest for alfalfa and red clover, and higher in excreta collected in morning than evening. Concentrations of neutral detergent fiber (NDF) in feces, of N in NDF (NDIN) and acid detergent fiber (ADIN), and relative amounts of NDIN and ADIN excreted in feces were significantly higher from cows fed high-tannin birdsfoot trefoil than the other silage types. Study results imply that collection of excreta for environmental studies needs to consider forage polyphenol and diurnal effects on chemistry of dairy excreta.
An evaluation of milk urea nitrogen (MUN) as a diagnostic of protein feeding in dairy cows was performed using mean treatment data (n = 306) from 50 production trials conducted in Finland (n = 48) and Sweden (n = 2). Data were used to assess the effects of diet composition and certain animal characteristics on MUN and to derive relationships between MUN and the efficiency of N utilization for milk production and urinary N excretion. Relationships were developed using regression analysis based on either models of fixed factors or using mixed models that account for between-experiment variations. Dietary crude protein (CP) content was the best single predictor of MUN and accounted for proportionately 0.778 of total variance [MUN (mg/dL) = -14.2 + 0.17 x dietary CP content (g/kg dry matter)]. The proportion of variation explained by this relationship increased to 0.952 when a mixed model including the random effects of study was used, but both the intercept and slope remained unchanged. Use of rumen degradable CP concentration in excess of predicted requirements, or the ratio of dietary CP to metabolizable energy as single predictors, did not explain more of the variation in MUN (R(2) = 0.767 or 0.778, respectively) than dietary CP content. Inclusion of other dietary factors with dietary CP content in bivariate models resulted in only marginally better predictions of MUN (R(2) = 0.785 to 0.804). Closer relationships existed between MUN and dietary factors when nutrients (CP to metabolizable energy) were expressed as concentrations in the diet, rather than absolute intakes. Furthermore, both MUN and MUN secretion (g/d) provided more accurate predictions of urinary N excretion (R(2) = 0.787 and 0.835, respectively) than measurements of the efficiency of N utilization for milk production (R(2) = 0.769). It is concluded that dietary CP content is the most important nutritional factor influencing MUN, and that measurements of MUN can be utilized as a diagnostic of protein feeding in the dairy cow and used to predict urinary N excretion.
Measurements of dairy manure nutrient availability to crops typically show great variability. Approaches that are more accurate are needed to improve manure management and reduce nutrient loss to the environment. In this study, we compared direct (15N recovery) and indirect (difference method [Diff Meth] and fertilizer equivalence [FE] approach) methods of determining first-year dairy manure N availability or recovery during three cropping seasons. A field experiment was conducted on a Plano silt loam (fine-silty, mixed, superactive, mesic Typic Argiudolls) planted to corn (Zea mays L.). Plots received either manure, fertilizer N, or no N. Microplots receiving 15N-labeled manure were also established each study year. Manure was applied to a new plot each cropping season. Whole-plant N uptake was the best crop parameter to use for FE estimates. Estimates of N availability by relative effectiveness (Rel Eff), which are derived from the Diff Meth, and FE were similar (32 and 41%, respectively) and higher than unlabeled N or 15N recovery measurements because these indices factor in N use efficiency. Measures of the Rel Eff of manure N use were highly affected by control plot N uptake. The FE approach is less influenced by control plots, but it requires the inclusion of several more treatments and use of mathematical functions to describe crop response to N. These limitations are reflected in the wide ranges obtained for N availability estimates (-60 to 148%). Although apparent N recovery by the Diff Meth (14%) or direct measurements of 15N recovery (16%) were close on average, variability tended to be much lower for the 15N method. In addition, the Diff Meth was highly dependent on initial soil conditions. Use of 15N-labeled manure, although more costly and time-consuming, provided more consistent and reliable results.
Improvements to the efficiency of dietary nitrogen use by lactating dairy cattle can be made by altering the concentration and form of protein in the diet. This study collected urine and feces from dairy cows from selected crude protein (CP) treatments of 2 lactation studies. In the first trial, collections were made from cattle fed a diet with high (19.4%) or low (13.6%) CP content (HCP and LCP, respectively). In the second trial, collections were made from cattle fed diets in which the forage legume component was alfalfa (ALF) or birdsfoot trefoil with a low (BFTL) or high (BFTH) concentration of condensed tannins (CT). A system of small laboratory chambers was used to measure NH3 emissions over 48 h from applications of equal quantities of urine and feces to cement (simulating a barn floor) and from applications of slurries, made by combining feces and urine in the proportions in which they were excreted for each treatment, to soil. Reducing dietary CP content resulted in less total N excretion and a smaller proportion of the excreted N being present in urine; urine N concentration was 90% greater for HCP than LCP. Surprisingly, NH3 emissions from the barn floor were similar in absolute terms despite the great differences in urine urea-N concentrations, presumably because urease activity was limiting. Cumulative emissions from fresh slurries applied to soil represented 18% of applied N for both HCP and LCP. Following storage at 20 degrees C for 2 wk, cumulative emissions from LCP were much lower than for HCP, representing 9 and 25% of applied N, respectively. Emissions were also lower when expressed as a proportion of slurry total ammoniacal N (TAN) content (24 and 31%, respectively) because of treatment differences in slurry pH. Increasing CT content of the dietary forage legume component resulted in a shift in N excretion from urine to feces. Cumulative NH3 emissions from the barn floor were greater for ALF than for BFTL or BFTH. Emissions from fresh and stored slurries were in proportion to slurry TAN contents, with approximately 35% of applied TAN being lost for all treatments. Emissions expressed as a proportion of total N applied were consistently lower for BFTH than for ALF.
Forty-five multiparous and 18 primiparous Holstein cows were fed three levels of crude protein (CP), each at three levels of neutral detergent fiber (NDF), to identify optimal dietary CP and energy. Cows were blocked by parity and days in milk into seven groups of nine and randomly assigned to an incomplete 9 x 9 Latin square trial with four, 4-wk periods. Diets were formulated from alfalfa and corn silages, high-moisture corn, soybean meal, minerals, and vitamins. Forage was 60% alfalfa and 40% corn silage on all diets; NDF contents of 36, 32, and 28% were obtained by feeding 75, 63, and 50% forage, respectively. Dietary CP contents of 15.1, 16.7, and 18.4% were obtained by replacing high-moisture corn with soybean meal. Production data were from the last 2 wk of each period. Spot fecal and urine samples were collected from 36 cows to estimate N excretion using fecal indigestible acid detergent fiber (ADF) and urinary creatinine as markers. There were no interactions (P > or = 0.08) between dietary CP and NDF for any trait; thus, effects of CP were not confounded by NDF or vice versa. Intake of DM and fat yield were lower on 15.1% CP than at higher CP. There were linear increases in milk urea and urinary N excretion and linear decreases in N efficiency with increasing CP. Increasing CP from 15.1 to 18.4% reduced milk N from 31 to 25% of dietary N, increased urinary N from 23 to 35% of dietary N, and reduced fecal N from 45 to 41% of dietary N. Decreasing NDF gave linear increases in BW gain, yield of milk, protein, true protein, lactose, and SNF, and milk/DM intake and milk N/N intake, and linear decreases in milk urea. However, fat yield was lower on 28% than 32% NDF. Reducing NDF from 36 to 28% increased purine derivative excretion by 19%, suggesting increased microbial protein. Increasing CP by adding soybean meal to diets fed cows averaging 34 kg/d of milk increased intake and fat yield but depressed N efficiency. Increasing dietary energy by reducing forage improved milk yield and efficiency and decreased excretion of environmentally labile urinary N.
Forty lactating Holstein cows, including 10 with ruminal cannulas, were blocked by days in milk into 8 groups and then randomly assigned to 1 of 8 incomplete 5 x 5 Latin squares to assess the effects of 5 levels of dietary crude protein (CP) on milk production and N use. Diets contained 25% alfalfa silage, 25% corn silage, and 50% concentrate, on a dry matter (DM) basis. Rolled high-moisture shelled corn was replaced with solvent-extracted soybean meal to increase CP from 13.5 to 15.0, 16.5, 17.9, and 19.4% of DM. Each of the 4 experimental periods lasted 28 d, with 14 d for adaptation and 14 d for data collection. Spot sampling of ruminal digesta, blood, urine, and feces was conducted on d 21 of each period. Intake of DM was not affected by diet but milk fat content as well as ruminal acetate, NH3, and branched-chain volatile fatty acids, urinary allantoin, and blood and milk urea all increased linearly with increasing CP. Milk and protein yield showed trends for quadratic responses to dietary CP and were, respectively, 38.3 and 1.18 kg/d at 16.5% CP. As a proportion of N intake, urinary N excretion increased from 23.8 to 36.2%, whereas N secreted in milk decreased from 36.5 to 25.4%, as dietary protein increased from 13.5 to 19.4%. Under the conditions of this study, yield of milk and protein were not increased by feeding more than 16.5% CP. The linear increase in urinary N excretion resulted from a sharp decline in N efficiency as dietary CP content increased.
An on-farm study of 54 representative Wisconsin dairy farms was conducted to evaluate the influence of biophysical and socioeconomic factors on overall feed, fertilizer, and manure nutrient use. This report validates 1) how well data on cow diets, feed analyses, and milk production reflected established feed-milk-manure relationships; and 2) how well farmer-recorded data on manure land application reflected literature values of manure N and P excretion, collection, and loss. Calculated feed N and P use efficiencies (18 to 33% and 18 to 35%, respectively) fell within ranges expected for dairy farms. This suggested that our on-farm methods of data collection provided reliable information on relationships among feed N and P intake, secretions in milk, and excretion in manure. On stanchion farms, there were no differences between farmer estimates (kg/farm) of manure P collected (1,140) and land-applied (1,210) and what would be calculated from the literature (1,340). On freestall farms, there were no differences in amounts (kg/farm) of manure P collected (2,889), land-applied (2,350), or literature estimates (2,675). Manure P applications (kg/ha) to tilled cropland would be similar using either farmer estimates of manure collected and land-applied, or literature estimates. The data provided a snapshot of Wisconsin industry practices, as well as information on the range of feed and manure management practices on individual dairy farms. Improvements to data collection methods would require increased skill and training of both farmers and those responsible for assisting farmers in on-farm data collection and analyses.
It is common practice to repeatedly apply dairy manure to the same fields. To accurately assess the total plant availability of manure nutrients, it is necessary to account for the nutrients remaining in soil from previous manure applications. A field experiment studying manure nitrogen (N) uptake by corn (Zea mays L.) was conducted from 1998 to 2003 on a Plano silt loam (fine-silty, mixed, mesic, Typic Argiudolls). Plots received two rates of semisolid manure either every year, every 2 yr, or every 3 yr to estimate first-, second-, and third-year dairy manure N residuals. Residual manure N availability was estimated from single and multiple manure applications using (i) the fertilizer N equivalence method, (ii) the apparent recovery (difference) method, (iii) relative effectiveness method, and (iv) recovery of (15)N-labeled manure. Second-year availabilities after a single manure application using the fertilizer equivalence, difference, and relative effectiveness methods were estimated to be 12, 8, and 4% of total manure N applications, respectively. Estimates of third-year availability by these methods were 3, 1, and 5%, respectively. Measurement of (15)N recovered from labeled manure was 6 and 2% in the second and third year, respectively. Fertilizer equivalence, difference, and relative effectiveness methods showed great year to year variability, reducing the confidence in the residual manure N availability estimates by these methods, but using (15)N-labeled manures reduced variability substantially. Based on this and other studies, we suggest that second- and third-year residual N availability from a single application of semisolid dairy manure would be 9 to 12%, and 3 to 5% of the original manure N application, respectively.
Two 4 x 4 Latin square trials (4-wk periods; 16 wk total) were conducted to see whether supplementing rumen-protected Met (RPM; fed as Mepron) would allow feeding less crude protein (CP), thereby reducing urinary N excretion, but without losing production. In trial 1, 24 Holsteins were fed 4 diets as total mixed rations containing [dry matter (DM) basis]: 18.6% CP and 0 g of RPM/d; 17.3% CP and 5 g of RPM/d; 16.1% CP and 10 g of RPM/d; or 14.8% CP and 15 g of RPM/d. Dietary CP was reduced by replacing soybean meal with high-moisture shelled corn. All diets contained 21% alfalfa silage, 28% corn silage, 4.5% roasted soybeans, 5.8% soyhulls, 0.6% sodium bicarbonate, 0.5% vitamins and minerals, and 27% neutral detergent fiber. There was no effect of diet on intake, weight gain, or yields of protein, lactose, and solids-not-fat. However, production was greater at 17.3% CP plus RPM and 16.1% CP plus RPM than on the other 2 diets. Apparent N efficiency (milk N:N intake) was greatest on the lowest CP diet containing the most RPM. Linear reductions in milk urea N and urinary N excretion were observed with lower dietary CP. In trial 2, 32 Holsteins were fed 4 diets as total mixed rations, formulated from ingredients used in trial 1 and containing 16.1 or 17.3% CP with 0 or 10 g of RPM/d. On average, cows were calculated to be in negative N balance on all diets because of lower than expected DM intake. There was no effect of RPM supplementation on any production trait. However, higher CP gave small increases in yields of milk, protein, and solids-not-fat and tended to increase DM intake and lactose yield. Apparent N efficiency was greater, and milk urea nitrogen was lower, on 16.1% CP. In trial 1, feeding lower CP diets supplemented with RPM resulted in improved N efficiency and reduced urinary N excretion. However, in trial 2, reducing dietary CP from 17.3 to 16.1% reduced milk secretion, an effect that was not reversed by RPM supplementation at low DM intakes when cows were apparently mobilizing body protein.
The distribution of (15)N in AA during [(15)N]Leu infusion and its impact on the estimation of endogenous nitrogen (EN) flows in dairy cows was evaluated in 4 lactating cows equipped with ruminal, duodenal (n = 4), and ileal (n = 2) cannulae fed a silage-based diet during a 35-d experimental period. To label EN, starting on d 27, an infusion of L-[(15)N]Leu (0.45 mmol/h) was performed for 200 h. Samples of feed, duodenal and ileal digesta, feces, blood, urine, and mucosa of the rumen and duodenum were taken at 0900, 1100, 1300, and 1500 h on d 34 and at 0800, 1000, 1200, and 1400 h on d 35. The enrichment and fluxes of total N and individual AA were determined and used to calculate the EN flows at the duodenum, ileum, and in the feces. Based on the concept that EN comprises desquamation and secretions, EN flows were estimated, using as representative of the enrichment of EN only the enrichment of the gut mucosa (upper limit) or the average of the mucosa and the export protein enrichment (assumed to have a similar enrichment to casein; lower limit). Estimations of duodenal and fecal EN flows using the isotope dilution of (15)N-total and (15)N-Leu were not different and EN was an important fraction of duodenal and fecal flows, representing 14 to 30% of the duodenal flow and 18 to 31% of the fecal flow, depending on the dilution method used. The total EN flow at the duodenum is present in approximately equal proportions as either free EN or EN incorporated into bacterial protein. Ileal EN flow was 18% greater than the fecal EN flow. Using the combination of the gut and export protein, the duodenal and fecal EN flows estimated with the isotopic dilution of Leu vs. other labeled AA were less different than when estimated using the enrichment of gut mucosa alone. The current approaches have highlighted that present prediction schemes probably underestimate EN flows at the duodenum and, in consequence, overestimate net protein and AA supply. Refinement of the procedures may allow direct and accurate estimation of metabolic fecal protein, an important component of the so-called maintenance requirement of dairy cows.
In this review, we examine the variation in stable isotope signatures of the lighter elements (H-2, C-13, N-15, O-18, and S-34) of tissues and excreta of domesticated animals, the factors affecting the isotopic composition of animal tissues, and whether stable isotopes may be used to differentiate organic and conventional modes of animal husbandry. The main factors affecting the C-13 signatures of livestock are the C3/C4 composition of the diet, the relative digestibility of the diet components, metabolic turnover, tissue and compound specificity, growth rate, and animal age. N-15 signatures of sheep and cattle products have been related mainly to diet signatures, which are quite variable among farms and between years. Although few data exist, a minor influence in N-15 signatures of animal products was attributed to N losses at the farm level, whereas stocking rate showed divergent findings. Correlations between mode of production and H-2 and O-18 have not been established, and only in one case of an animal product was S-34 a satisfactory marker for mode of production. While many data exist on diet-tissue isotopic discrimination values among domesticated animals, there is a paucity of data that allow a direct and statistically verifiable comparison of the differences in the isotopic signatures of organically and conventionally grown animal products. The few comparisons are confined to beef, milk, and egg yolk, with no data for swine or lamb products. C-13 appears to be the most promising isotopic marker to differentiate organic and conventional production systems when maize (C4) is present in the conventional animal diet. However, C-13 may be unsuitable under tropical conditions, where C4 grasses are abundant, and where grass-based husbandry is predominant in both conventional and organic systems. Presently, there is no universal analytical method that can be applied to differentiate organic and conventional animal products.
Two trials were conducted simultaneously to study the effects of varying alfalfa silage (AS) to corn silage (CS) ratio in diets formulated to avoid excess protein or starch on lactating dairy cow performance, digestibility, ruminal parameters, N balance, manure production and composition, and gaseous emissions [carbon dioxide (CO2), methane (CH4), and ammonia-N (NH3-N)]. In trial 1 all measurements, except gas emissions, were conducted on 8 rumen-cannulated cows in replicated 4 × 4 Latin squares. In trial 2, performance and emissions were measured on 16 cows randomly assigned to 1 of 4 air-flow controlled chambers in a 4 × 4 Latin square. Dietary treatments were fed as total mixed rations with forage-to-concentrate ratio of 55:45 [dietary dry matter (DM) basis] and AS:CS ratios of 20:80, 40:60, 60:40, and 80:20 (forage DM basis). Measurements were conducted the last 3 d of each 21-d period. Treatments did not affect DM intake, DM digestibility, and milk/DM intake. However, responses were quadratic for fat-and-protein-corrected milk, fat, and protein production, which reached predicted maxima for AS:CS ratio of 50:50, 49:51, and 34:66, respectively. Nitrogen use efficiency (milk N/N intake) decreased from 31 to 24 g/100 g as AS:CS ratio increased from 20:80 to 80:20. Treatments did not alter NH3-N/milk-N but tended to have a quadratic effect on daily NH3-N emission. Treatments had a quadratic effect on daily CH4 emission, which was high compared with current literature; they influenced CH4 emission per unit of neutral detergent fiber (NDF) intake and tended to influence CO2/NDF intake. Ruminal acetate-to-propionate ratio and total-tract NDF digestibility increased linearly with increasing AS:CS ratio. In addition, as AS:CS ratio increased from 20:80 to 80:20, NDF digested increased linearly from 2.16 to 3.24 kg/d, but CH4/digested NDF decreased linearly from 270 to 190 g/kg. These 2 counterbalancing effects likely contributed to the observed quadratic response in daily CH4 emission, which may have been influenced also by increasing starch with increasing CS in the diet as reflected by the increased ruminal propionate molar proportion. Overall, production performances were greatest for the intermediate AS:CS ratios (40:60 and 60:40), but daily excretion of urine, manure, fecal N, urinary urea N, and urinary N decreased with increasing proportion of CS in the diet, whereas daily CH4 emission was reduced for the 2 extreme AS:CS ratios (20:80 and 80:20). However, the proportion of AS and CS in the diet did not affect CH4/fat-and-protein corrected milk.
The influence of dairy cattle feed composition on the manure composition and on the dynamics and plant availability of cattle slurry N was studied. Dairy cows were fed seven different forages either with or without supplemental concentrates. The concentration of N in faeces dry matter varied from 18 to 38 g/kg dry matter and increased with increasing digestibility of the feed. Cattle slurries consisting of a mixture of 0·5 faecal N and 0·5 urinary N were stored according to common agricultural practice in Northern Europe. The mineralization of faecal N during slurry storage was very variable (0·09–0·50). The plant availability of N in the slurries originating from cattle fed with known diets was tested in small, framed field plots with spring barley, under conditions with minimal N losses. The nitrogen uptake in barley was determined and the mineral fertilizer equivalent (MFE) of slurry N was calculated. The net release of mineral N and CO2 from the slurries in soil was also measured in a parallel incubation study. The MFE of cattle slurry N varied from 53 to 75%. After correcting for the measured urine-N/faeces-N ratio and expected ammonia emission, the MFE varied from 51 to 78%. The plant availability and net release of cattle slurry N were influenced by forage type and feeding level. The MFE was negatively correlated with the concentration of crude fibre and neutral detergent fibre (NDF) in the diet, and positively correlated with the dietary protein content. The net release of CO2 from the slurries after 12 weeks in soil was significantly influenced by the concentration of crude fibre in the diet. The plant availability of slurry N was significantly correlated with the ammonium content (R2=0·53) and negatively correlated with the slurry C[ratio]N ratio (R2=0·67) and the dry matter[ratio]N ratio (R2=0·58). Residual slurry N left in the soil after harvest of the first crop varied from 0·25 to 0·47 of total slurry N. It is concluded that the fibre and the protein content of cattle diets have a significant influence on the plant availability of cattle slurry N and on the amount of residual slurry N remaining in the soil after the first growing season.
The use of15N as a tracer in soil/plant research is examined. The limitations of the so-called Ndff approach are discussed to show the need to consider not just the fate of the added label but also the path that was followed and the rate of the transformation. The development of15N isotope dilution techniques to determine gross rates of nitrogen transformation in soil is reviewed with some indications as to the further development of the approach.
Nitrogen (N) utilisation by crops has to be improved to minimize losses to the environment. We investigated N use efficiency
of animal manure and mineral fertiliser and fate of fertiliser N not taken up by crops in a conventional (CONMIN) and a bio-organic
(BIOORG) cropping system of a long-term field experiment over three vegetation periods (winter wheat–soybean–maize). Microplots
planted with wheat received a single application of 15N-labelled slurries (either urine or faeces labelled) or mineral fertiliser. At the end of each vegetation period we tested
whether higher microbial activity and larger microbial biomass in BIOORG than CONMIN soils, and lower long-term N input level
in BIOORG, affected use efficiency and fate of fertiliser N not taken up by crops. Recovery of 15N in wheat was 37%, 10% and 47% from urine, faeces and mineral fertiliser, respectively, and decreased strongly in the residual
years. In total 41%, 15% and 50% of 15N applied as urine, faeces and mineral fertiliser was recovered by the three crops. 15N recovered from originally applied urine, faeces and mineral fertiliser in the topsoil (0–18 cm) at the end of the third
vegetation period was 19%, 25% and 20%, respectively. Of urine-, faeces- and mineral fertiliser-15N, 40%, 61% and 29%, respectively, was not recovered by the three crops and in topsoil suggesting significant transport of
15N-labelled components to deeper soil layers. CONMIN and BIOORG differed neither in fertiliser N use efficiency by crops nor
in 15N recovery in soil indicating insignificant difference in the turnover and utilization of the applied manure nitrogen in the
conventional and the bio-organic cropping systems.
A sheep was fed on15N-labelled ryegrass hay during a period of 9 days in order to obtain15N-labelled manure. After 9 days of feeding, the total N in faeces contained 3.70 atom %15N excess, which was equivalent to 82% of the15N enrichment of the hay N. The easily-decomposable fraction of the faecal N was less labelled (2.89 atom %15N excess) than the slowly-decomposable fraction. The15N enrichment of mineralized faecal N did not change significantly during 32 weeks of incubation in sand. About 25% of the faecal N was water-soluble. This N had a higher15N enrichment than the total faecal N, indicating that a part of the water-soluble N was indigestible feed N. The faeces contained only small amounts of NH4+-N, which had a15N enrichment similar to the15N enrichment of N mineralized during incubation in sand. It is suggested that the labelled faecal N obtained after a few days of feeding on labelled feed could be divided in two N pools: A decomposable N fraction (about 60%) with a15N enrichment similar to the enrichment of N mineralized in sand (2.89 ± 0.09 atom %15N excess), and a very slowly-decomposable N fraction (about 40%) with a15N enrichment similar to that of the feed (4.52 atom %15N excess).
A modified mathematical model is described that simulates the dynamics of rumen micro-organisms, with specific emphasis on the rumen protozoa. The model is driven by continuous inputs of nutrients and consists of nineteen state variables, which represent the N, carbohydrate, fatty acid and microbial pools in the rumen. Several protozoal characteristics were represented in the model, including preference for utilization of starch and sugars compared with fibre, and of insoluble compared with soluble protein; engulfment and storage of starch; no utilization of NH3 to synthesize amino acids; engulfment and digestion of bacteria and protozoa; selective retention within the rumen; death and lysis related to nutrient availability. Comparisons between model predictions and experimental observations showed reasonable agreement for protozoal biomass in the rumen, but protozoal turnover time was not predicted well. Sensitivity analyses highlighted the need for more reliable estimates of bacterial engulfment rate, protozoal maintenance requirement, and death rate. Simulated protozoal biomass was increased rapidly in response to increases in dietary starch content, but further increases in starch content of a high-concentrate diet caused protozoal mass to decline. Increasing the sugar content of a concentrate diet, decreased protozoa, while moderate elevations of the sugar content on a roughage diet increased protozoal biomass. Simulated protozoal biomass did not change in response to variations in dietary neutral-detergent fibre (NDF) content. Reductions in dietary N resulted in an increased protozoal biomass. Depending on the basal intake level and dietary composition, protozoal concentration in the rumen was either increased or decreased by changes in feed intake level. Such changes in relative amounts of protozoal and bacterial biomass markedly affected the supply of nutrients available for absorption. The integration of protozoal, bacterial and dietary characteristics through mathematical representation provided an improved understanding of mechanisms of protozoal responses to changes in dietary inputs.
The objective of this review is to describe recent research findings related to the use of milk or blood urea nitrogen to identify inefficiencies in protein nutrition and estimate nitrogen excretion. A mathematical model was developed to integrate milk urea nitrogen (MUN) and milk composition to predict urinary and fecal excretion, intake, and utilization efficiency for nitrogen in lactating dairy cows. This model was subsequently used to develop target MUN concentrations for lactating dairy cattle fed according to National Research Council recommendations. Further research identified a change in measurement of MUN by Dairy Herd Improvement Associations, and subsequently resulted in adjustments to the model. Target MUN concentrations for most dairy herds bulk tank samples are between 8 to 12 mg/dl. Urinary nitrogen (g/d) can be estimated as 0.026 times MUN (mg/dl) times body weight (kg) for dairy cattle. A similar approach can be used with blood or plasma urea nitrogen. Because blood or plasma urea is higher than MUN, the coefficient relating blood urea to urinary N is lower than for MUN. Urinary nitrogen (g/d) can be estimated as 0.013 times MUN (mg/dl) times body weight (kg) for cattle, sheep, goats and horses. However, pigs and rats were found to be more efficient at clearing urea from the blood, and therefore, higher coefficients are used to relate blood urea concentration to N excretion rate for these species. Several extension and field research projects using MUN have been implemented. Bulk tank samples are used to identify herds with either chronic or occasional herd nutrition problems. Herds with high MUN have been found to be at risk for over feeding protein and herds with low MUN have been found to be at risk for under feeding protein.
Little is known about nitrogen (N) forms in ruminant feces, although this information is important to understand N dynamics
in agro-ecosystems. We fed 15N labeled ryegrass hay to a sheep and collected 15N labeled feces. Nitrogen forms in the feces were characterized by chemical extractions, solid-state cross polarization 15N nuclear magnetic resonance spectroscopy (SS CP/MAS 15N NMR) and Curie-point pyrolysis–gas chromatography/mass spectrometry (Cp Py-GC/MS). A 4months incubation experiment was
conducted to assess N release from the feces. Half of the fecal N could be ascribed to bacterial and endogenous debris and
a third to undigested dietary N. About a tenth of the fecal N was mineralized during the incubation experiment. The 15N abundance of nitrate released during the incubation remained constant and close to the 15N abundance of the total feces N. The NMR analysis of the feces showed that most of the N was present in proteins, while some
was present as heterocyclic N, amino acids and ammonium. The Cp Py-GC/MS analysis confirmed the presence of proteins, amino
acids and heterocyclic N in the feces. Comparing these results to those obtained from the 15N labeled hay suggests that some N compounds present in the plant were not digested by the animal, and that the animal excreted
de novo synthesized N compounds. The low content in ammonium and amino acids, the low rate of N release from these feces during
the incubation and the relatively high fecal protein content, particularly the hard to mineralize undigested and microbially
bound forms, can explain the low transfer of N from these feces to crops observed in a previous work.
KeywordsRyegrass hay–Sheep feces–
15N labeling–Curie-point pyrolysis–gas chromatography/mass spectrometry–Solid state cross polarization 15N nuclear magnetic resonance
Mechanisms of soil organic carbon (C) and nitrogen (N) stabilization are of great interest, due to the potential for increased
CO2 release from soil organic matter (SOM) to the atmosphere as a result of global warming, and because of the critical role
of soil organic N in controlling plant productivity. Soil proteins are recognized increasingly as playing major roles in stabilization
and destabilization of soil organic C and N. Two categories of proteins are proposed: detrital proteins that are released
upon cell death and functional proteins that are actively released into the soil to fulfill specific functions. The latter
include microbial surface-active proteins (e.g., hydrophobins, chaplins, SC15, glomalin), many of which have structures that
promote their persistence in the soil, and extracellular enzymes, responsible for many decomposition and nutrient cycling
transformations. Here we review information on the nature of soil proteins, particularly those of microbial origin, and on
the factors that control protein persistence and turnover in the soil. We discuss first the intrinsic properties of the protein
molecule that affect its stability, next possible extrinsic stabilizing influences that arise as the proteins interact with
other soil constituents, and lastly controls on accessibility of proteins at coarser spatial scales involving microbial cells,
clay particles, and soil aggregates. We conclude that research at the interface between soil science and microbial physiology
will yield rapid advances in our understanding of soil proteins. We suggest as research priorities determining the relative
abundance and turnover time (age) of microbial versus plant proteins and of functional microbial proteins, including surface-active
compounds.
Zein is the major storage protein of corn and comprises ≈45–50% of the protein in corn. It was first identified in 1897, based on its solubility in aqueous alcohol solutions. Zein isolate is not used directly for human consumption due to its negative nitrogen balance and poor solubility in water. Current zein manufacture is limited to ≈500 tonnes per year from corn gluten meal. Zein sells for ≈US$10–40 per kilogram, depending on purity. The ability of zein and its resins to form tough, glossy, hydrophobic grease-proof coatings and their resistance to microbial attack have been of commercial interest. Potential applications of zein include use in fiber, adhesive, coating, ceramic, ink, cosmetic, textile, chewing gum and biodegradable plastics. These new applications of zein appear promising, but requires the development of low-cost manufacturing methods. This paper reviews the present status of the chemistry, properties, uses and methods of manufacturing zein. The characteristics of zein are discussed in terms of its composition, structure, solubility in various solvents and gelation properties.
Reducing ammonia (NH3) emissions through slurry incorporation or other soil management techniques may increase nitrate (NO3) leaching, so quantifying potential losses from these alternative pathways is essential to improving slurry N management. Slurry N losses, as NH3 or NO3 were evaluated over 4 yr in south-central Wisconsin. Slurry (i.e., dairy cow [Bos taurus] manure from a storage pit) was applied each spring at a single rate (-75 m3 ha(-1)) in one of three ways: surface broadcast (SURF), surface broadcast followed by partial incorporation using an aerator implement (AER-INC), and injection (INJ). Ammonia emissions were measured during the 120 h following slurry application using chambers, and NO3 leaching was monitored in drainage lysimeters. Yield and N3 uptake of oat (Avena sativa L.), corn (Zea mays L.), and winter rye (Secale cereale L.) were measured each year, and at trial's end soils were sampled in 15- to 30-cm increments to 90-cm depth. There were significant tradeoffs in slurry N loss among pathways: annual mean NH3-N emission across all treatments was 5.3, 38.3, 12.4, and 21.8 kg ha(-1) and annual mean NO3-N leaching across all treatments was 24.1, 0.9, 16.9, and 7.3 kg ha' during Years 1, 2, 3, and 4, respectively. Slurry N loss amounted to 27.1% of applied N from the SURF treatment (20.5% as NH3-N and 6.6% as NO,-N), 23.3% from AER-INC (12.0% as NH3-N and 11.3% as NO3-N), and 9.19% from INJ (4.4% as NH3-N and 4.7% as NO3-N). Although slurry incorporation decreased slurry N loss, the conserved slurry N did not significantly impact crop yield, crop N uptake or soil properties at trial's end.
Human activities have increased the amount of earth's reactive N, resulting in significant improvements in crop yield and animal production but also in environmental degradation and ecosystem disruption in some areas. For example, agriculture has been cited as a major source of N that contributes to hypoxia in the Gulf of Mexico. Although other sources of N have been well characterized in large ecosystem studies, the contribution of legume crops to the N cycle has not. Furthermore, the role legumes play in reducing excess N is not widely recognized. Symbiotic N2 fixation is a facultative process that is reduced by plant N uptake from other sources. Using reported and estimated crop yield and protein concentration with published estimates of soil N mineralization and atmospheric N deposition, we estimated spatial patterns of symbiotic N2 fixation for soybean Glycine max (L.) Merr. and alfalfa (Medicago sativa L.) across the Mississippi River Basin, the largest in North America. We estimate that alfalfa haylage adds about 20% to total production of dry alfalfa hay and increases total land area in alfalfa by about 11% over that reported in the Census of Agriculture. Our analysis shows wide ranges in N2 fixation (0 to 185 kg N ha(-1) for soybean and 45 to 470 kg N ha(-1) for alfalfa), reasonable mean rates (84 kg N ha(-1) for soybean and 152 kg N ha(-1) for alfalfa), and suggests that about 2.9 million Mg of fixed N is harvested annually in these two cultivated legumes.
Die Trennung von Kot-N beim Schaf durch Detergentien und die Schätzung der wahren Verdaulichkeit des Nahrungs-N und der Ausscheidung von Nicht-Nahrungs-N im Kot
In einer früheren Arbeit (mason 1969) wurde gezeigt, daß der Stickstoff im Kot durch Extraktion mit sauren oder neutralen Detergentien (van Soest 1963) in zwei Fraktionen eingeteilt werden kann, und zwar in eine unverdauliche Fraktion, die direkt aus dem Futter stammt, und in eine zweite Fraktion, die nicht direkt aus dem Futter stammt. Die gegenwärtige Arbeit beschreibt weitere Untersuchungen auf diesem Gebiet mit Schafkot aus Verdaulichkeitsversuchen, in denen 47 verschiedene Futtermittel und Futtermischungen getestet wurden.
Mit wenigen Ausnahmen wurde mehr als 80% der gesamten Stickstoffmenge im Kot mit Hilfe von Detergentien extrahiert. Die Säureextraktion erwies sich in dieser Beziehung als effektiver als die neutrale Extraktion.
Bestimmungen der wahren Verdaulichkeit des Futter-N, die auf der Grundlage der N-Aufnahme und der Ausscheidung des unverdaulichen Stickstoffes gemacht wurden, lagen im Bereich von 90 bis 99 % und zeigten eine sehr gute übereinstimmung mit Ergebnissen, die mit Hilfe von Regressionsverfahren erzielt worden sind.
Die Ausscheidung der N-Menge, die nicht direkt dem Futter entstammt (non-dietary faecal nitrogen = NDFN = umgesetzte Kot-N-Menge) variierte von 3,6 bis
8.0 g pro kg verzehrte Trockensubstanz, der Modus dieses Verhältnisses lag zwischen 5.1 und 5,7 g NDFN/kg Trockensubstanzaufnahme.
Es wird abschließend festgestellt, daß für normale Futterrationen, in denen das Zellwandmaterial chemisch intakt ist, der Kot-N in die erwähnten zwei Fraktionen eingeteilt werden kann mit Hilfe saurer oder neutraler Detergentien.
A retrospective observational study was conducted using data from Dairy Herd Improvement monthly tests to investigate the association between milk urea nitrogen (MUN) concentration and milk yield, milk protein, milk fat percentage, SCC, and parity for commercial Holstein and Jersey herds in Utah, Idaho, and Montana. Mean MUN for Holstein cows was 15.5 mg/ dl (5.5 mmol/L) MUN and 14.1 mg/dl (5.0 mmol/L) for Jersey cows. Mean MUN, categorized by 30-d increments of days in milk (DIM), paralleled changes in milk values and followed a curvilinear shape. For Holstein cows, concentrations of MUN were different among lactation groups 1, 2, and 3+ for the first 90 DIM for Holsteins. Overall, concentrations of MUN were lower during for the first 30 DIM compared with all other DIM categories for both Holstein and Jersey cows. Multivariate regression models of MUN by milk protein showed that as the milk protein percentage increased, MUN concentration decreased; however, models for Jersey cows showed that MUN did not decrease significantly until above 3.4% milk protein. Milk fat percentage also decreased as MUN increased, but by only 1 mg/dl MUN over the range of 2.2 to 5.8% milk fat. Somatic cell count showed a negative relationship with MUN. Holstein cows with milk protein percentage >3.2% had lower MUN compared with cows having milk protein <3.2% for milk yields from 27.3 to 54.5 kg/d and lower than cows having a milk protein <3.0% for milk yield of 54.5 to 63.6 kg/d. In Jersey cows, MUN concentrations were not different among milk protein percentage categorized by milk yield. This study found that MUN was inversely associated with milk protein percentage and paralleled change in milk yield over time.
The objective of this study was to determine composition, particle size distribution, and in vivo kinetics of ruminal particles having functional specific gravity (FSG) greater or less than FSG of particles found in the omasum and reticulum of lactating dairy cows. Particles from the reticulum and the omasal had FSG of 1.03 and 1.02, respectively. Particles from ruminal contents with FSG higher (HP) or lower (LP) than 1.02 were isolated and labeled with Er or Dy, respectively. Four ruminally cannulated, lactating Ayrshire dairy cows were fed all-grass silage (AS) or 54% grass silage:46% concentrate (SC) diets in a cross-over design trial and used to study chemical composition and ruminal and total tract kinetics of HP and LP. Labeled particles were pulse dosed into the rumen of the cows and disappearance of the markers from ruminal HP and LP pools and excretion in feces was monitored for 72 and 120 h, respectively. Fecal marker excretion data were fitted using two-compartment mathematical age-dependent/age-independent (Gn-->G1) models. Inclusion of concentrate in the diet (SC) increased (P < 0.05) apparent total tract digestibility of dietary DM, OM and N. Digestibility of fiber fractions, NDF and ADF, was lower (P < 0.01 and P < 0.05, respectively) for SC compared with AS. The heavy particles had higher (P < 0.01) indigestible NDF and lower (P < 0.01) N concentration than LP. Particles from the HP pool passed from the rumen more rapidly (P < 0.01) than particles from LP (0.044 and 0.019 h(-1), respectively). Diet had no effect on particle rate of disappearance or pool size in the rumen. Across diets, pool size of LP was consistently larger (P < 0.05) than that of HP. Diet had no effect on total tract mean retention time (MRT) of LP or HP. Total tract MRT of LP was greater (P < 0.05) than MRT of HP (59.6 vs. 49.0 h, respectively). Results from this study support the hypothesis that functional specific gravity is an important factor determining the rate of outflow and residence time of feed particles within the reticulo-rumen and total digestive tract. Our data indicate that digesta particles with functional specific gravity greater or less than 1.02 have different composition and flow characteristics. Heavier particles contain more indigestible fiber and less N and are likely depleted of substrate available for microbial fermentation, are smaller in size, and have a higher passage rate/shorter retention time in the digestive tract than lighter particles.
Enteric methane in dairy cattle production: quantifying the opportunities and impact of reducing emissions
- J R Knapp
- G L Laur
- P A Vadas
- W P Weiss
- J M Tricarico
Knapp, J.R., Laur, G.L., Vadas, P.A., Weiss, W.P., Tricarico, J.M., 2014. Enteric methane
in dairy cattle production: quantifying the opportunities and impact of reducing
emissions. J. Dairy Sci. 97, 3231-3261.
Nutrient Application Guidelines for Field and Vegetable Crops in Wisconsin Universtiy of Wisconsin Cooperative Extension Pub. A280. http://learningstore.uwex.edu/Nutrient-ApplicationGuidelines-for-Field-Vegetable-and-Fruit-Crops-in-Wisconsin-P185C0
- C A M Laboski
- J B Peters
- L D Bundy
Laboski C.A.M., Peters J.B., Bundy L.D., 2006. Nutrient Application Guidelines for
Field and Vegetable Crops in Wisconsin. Universtiy of Wisconsin Cooperative
Extension Pub. A280. http://learningstore.uwex.edu/Nutrient-ApplicationGuidelines-for-Field-Vegetable-and-Fruit-Crops-in-Wisconsin-P185C0.aspx/
(accessed 15.01.17).
QuickChem 1 Method 13-107-06-2-D
- Lachat Instruments
Lachat Instruments. 1996. QuickChem 1 Method 13-107-06-2-D. Mequon,
Wisconsin.
Substitutions of corn silage, alfalfa silage and corn grain in cow rations impact N use and N loss from dairy farmsProceedings of the 2016 International Nitrogen Initiative Conference, Solutions to Improve Nitrogen Use Efficiency for the World
- J M Powell
- C A Rotz
- P A Vadas
- K F Reed
Powell, J.M., Rotz, C.A., Vadas, P.A., Reed, K.F., 2016. Substitutions of corn silage,
alfalfa silage and corn grain in cow rations impact N use and N loss from dairy
farmsProceedings of the 2016 International Nitrogen Initiative Conference,
Solutions to Improve Nitrogen Use Efficiency for the World, 4-8 December 2016,
Melbourne, Australia.. (accessed 15.01.17) www.ini2016.com/.
The environmental impacts of N2 fixation by alfalfaProceedings, 34th California Alfalfa Symposium and 2004 National Alfalfa Symposium
- M P Russelle
Russelle, M.P., 2004. The environmental impacts of N2 fixation by
alfalfaProceedings, 34th California Alfalfa Symposium and 2004 National Alfalfa
Symposium, 13-15 December 2004, San Diego, CA, UC Cooperative Extension,
University of California, Davis, 95616.. (accessed 15.01.17) http://alfalfa.ucdavis.
edu/+symposium/proceedings/search.aspx?q=russelle/.
A macro for converting mean separation output to letter groupings in Proc Mixed
- Sas Institute
- N C Cary
- A M Saxton
SAS Institute. 2007. SAS/Stat user's guide. Version 9.2. SAS Institute Inc., Cary, NC.
Saxton, A.M., 1998. A macro for converting mean separation output to letter
groupings in Proc Mixed. In Proc. 23rd SAS Users Group Intl., SAS Institute, Cary,
NC, pp. 1243-1246.