Effects of a combination of feed additives on methane production, diet digestibility, and animal performance in lactating dairy cows.
ABSTRACT Two experiments were conducted to assess the effects of a mixture of dietary additives on enteric methane production, rumen fermentation, diet digestibility, energy balance, and animal performance in lactating dairy cows. Identical diets were fed in both experiments. The mixture of feed additives investigated contained lauric acid, myristic acid, linseed oil, and calcium fumarate. These additives were included at 0.4, 1.2, 1.5, and 0.7% of dietary dry matter, respectively (treatment ADD). Experimental fat sources were exchanged for a rumen inert source of fat in the control diet (treatment CON) to maintain isolipidic rations. Cows (experiment 1, n=20; experiment 2, n=12) were fed restricted amounts of feed to avoid confounding effects of dry matter intake on methane production. In experiment 1, methane production and energy balance were studied using open-circuit indirect calorimetry. In experiment 2, 10 rumen-fistulated animals were used to measure rumen fermentation characteristics. In both experiments animal performance was monitored. The inclusion of dietary additives decreased methane emissions (g/d) by 10%. Milk yield and milk fat content tended to be lower for ADD in experiment 1. In experiment 2, milk production was not affected by ADD, but milk fat content was lower. Fat- and protein-corrected milk was lower for ADD in both experiments. Milk urea nitrogen content was lowered by ADD in experiment 1 and tended to be lower in experiment 2. Apparent total tract digestibility of fat, but not that of starch or neutral detergent fiber, was higher for ADD. Energy retention did not differ between treatments. The decrease in methane production (g/d) was not evident when methane emission was expressed per kilogram of milk produced. Feeding ADD resulted in increases of C12:0 and C14:0 and the intermediates of linseed oil biohydrogenation in milk in both experiments. In experiment 2, ADD-fed cows tended to have a decreased number of protozoa in rumen fluid when compared with that in control cows. Total volatile fatty acid concentrations were lower for ADD, whereas molar proportions of propionate increased at the expense of acetate and butyrate.
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ABSTRACT: Two concentrates (MELK and VEM) with two different carbohydrate compositions were supplemented during milking in an Automatic Milking System (AMS). The objectives of this study were to estimate the effect of the concentrates on CH4 emission from dairy cows and to investigate the precision of the CO2-method when measuring in an AMS for different length of time. Holstein cows (n=36) were used with mean body weight of 660 kg (SD=75.13) and average milk production of 31.7 kg (SD=8.98), mixed parity and mixed lactation. Cows were allocated in two groups (n=18). After an adaptation period (period 1), each group received either 100% MELK (More Energy Lactating Cows; a newly introduced feeding system) or 100% VEM (Feed Value System for milk production) during periods 2 and 3. Besides, both groups were fed the same Total Mixed Ration (TMR) ad libitum in the stable. Air samples in the AMS from a point near the cows head were analysed every 20 seconds using the Gasmet equipment based on Fourier Transform Infrared (FTIR) Spectroscopy Technique. The equipment ran continuously for 15 days over the three measurement periods (5 days x 3 periods) with a 14 days waiting time in between the periods. Individual records of the CH4 and CO2 concentrations in the cows breath was calculated after subtracting the CH4 and CO2 concentrations in the stable air from the measured concentrations. The CH4:CO2 ratio was then multiplied with the calculated total CO2 production by the individual cows to get the quantitative CH4 production. Milk production and total dry matter intake (DMI, kg/day) were very similar in the two groups. The supplemented concentrate was allocated according to the individual milk yield and the intake ranged from 1.60 to 7.30 kg/day in MELK cows and from 2.06 to 7.20 kg/day in VEM cows. No significant difference was found for CH4 production in MELK and VEM groups over the three periods. A linear positive relation between the CH4 (g/day) and energy corrected milk (ECM, kg/day) production and the feed intake (DMI, kg/day) was observed for the entire period. The calculated CO2 and CH4 production were very similar in the two groups throughout the entire measurement period. The analysis of the precision of the CO2-method, using a 95% significance level, indicated that showing a difference of 9 or 5% in methane production requires a measuring period of 5 or 15 days, respectively, when using 18 cows per group. The study shows no effect of a limited change in supplementation of starch and sugar on CH4 production through feeding concentrates MELK or VEM in the AMS. To obtain an effect of changing the carbohydrate composition of the diet on the CH4 production, it is likely that a larger change in the diet is necessary. This can only efficiently be done by changing the TMR part of the diet.Livestock Science 06/2014; · 1.25 Impact Factor
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ABSTRACT: A dynamic, mechanistic model of the sulfur hexafluoride (SF6) tracer technique, used for estimating methane (CH4) emission rates from ruminants, was constructed to evaluate the accuracy of the technique. The model consists of six state variables and six zero-pools representing the quantities of SF6 and CH4 in rumen and hindgut fluid, in rumen and hindgut headspace, and in blood and collection canister. The model simulates flows of CH4 and SF6 through the body, subsequent eructation and exhalation and accumulation in a collection canister. The model predicts CH4 emission by multiplying the SF6 release rate of a permeation device in the rumen by the ratio of CH4:SF6 in collected air. This prediction is compared with the actual CH4 production rate, assumed to be continuous and used as a driving variable in the model. A sensitivity analysis was conducted to evaluate the effect of changes in several parameters. The predicted CH4 emission appeared sensitive to parameters affected by the difference in CH4:SF6 ratio in exhaled and eructed air respectively, viz., hindgut fractional passage rate and hindgut CH4 production. This is caused by the difference in solubility of CH4 and SF6 and by hindgut CH4 production. In addition, the predicted CH4 emission rate appeared sensitive to factors that affect proportions of exhaled and eructed air sampled, i.e., eructation time fraction, exhalation time fraction, and distance from sampling point to mouth/nostrils. Changes in rumen fractional passage rate, eructation rate, SF6 release rate, background values and air sampling rate did not noticeably affect the predicted CH4 emission. Simulations with (13)CH4 as an alternative tracer show that the differences and sensitivity to parameters greatly disappear. The model is considered a useful tool to evaluate critical points in the SF6 technique. Data from in vivo experiments are needed to further evaluate model simulations.Journal of Theoretical Biology 03/2014; · 2.35 Impact Factor
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ABSTRACT: The growing demand for sustainable animal production is compelling researchers to explore the potential approaches to reduce emissions of greenhouse gases from livestock that are mainly produced by enteric fermentation. Some potential solutions, for instance, the use of chemical inhibitors to reduce methanogenesis, are not feasible in routine use due to their toxicity to ruminants, inhibition of efficient rumen function or other transitory effects. Strategies, such as use of plant secondary metabolites and dietary manipulations have emerged to reduce the methane emission, but these still require extensive research before these can be recommended and deployed in the livestock industry sector. Furthermore, immunization vaccines for methanogens and phages are also under investigation for mitigation of enteric methanogenesis. The increasing knowledge of methanogenic diversity in rumen, DNA sequencing technologies and bioinformatics have paved the way for chemogenomic strategies by targeting methane producers. Chemogenomics will help in finding target enzymes and proteins, which will further assist in the screening of natural as well chemical inhibitors. The construction of a methanogenic gene catalogue through these approaches is an attainable objective. This will lead to understand the microbiome function, its relation with the host and feeds, and therefore, will form the basis of practically viable and eco-friendly methane mitigation approaches, while improving the ruminant productivity.Applied Microbiology and Biotechnology 11/2013; · 3.81 Impact Factor