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Effect of Type of Protein Supplementation on Duodenal Amino Acid Flow and Absorption in Lactating Dairy Cows
Abstract
Four multiparous lactating Holstein cows, fitted with cannulas in the rumen, duodenum, and ileum, were used in a trial with a 4 x 4 Latin square design to examine the effect of source and degradability of dietary CP supplements on AA flow and absorption in the small intestine. The CP supplements consisted of fish meal or meat meal as the animal by-products supplement and soybean meal or heated soybean meal as the plant by-products supplement. Fish meal and heated soybean meal constituted the high RUP diets, and meat meal and soybean meal constituted the low RUP diets. Dry matter intakes were similar among treatments. However, intakes of OM, rumen-degradable OM, total CP, and RDP were affected by the source of the CP supplement and were higher for diets with plant by-products than for those diets with animal by-products. Data were similar for the calculated in situ digestibilities and for true in vivo digestibilities of rumen-degradable OM. Efficiency of bacterial CP synthesis was similar among diets; however, nonbacterial CP flow to the duodenum and OM, CP, and disappearance of AA from the small intestine were affected by the interaction of supplement source and degradability. Heat treatment of soybean meal reduced the availability of most of the essential AA for absorption in the small intestine by 2.3% compared with that of soybean meal; the biggest such reduction (20%) occurred for Met. Availability of AA in the small intestine was affected by source and degradability of the CP dietary supplement. Heat treatment at 140 degrees C for 2.5 h reduced the availability of Met absorption from the small intestine. Although the differences among availabilities of the individual AA in the small intestine ranged from 80 to 84% among treatments, for high yielding cows, these differences may have practical significance.
... Ruminants fitted with cannulas in the rumen and duodenum are generally used to estimate the flow and disappearance of nutrients from different segments of the digestive tract (Titgemeyer, 1997), and to determine the supply and availability of amino acids (AA) to the animal (Windschitl and Stern, 1988;Ludden and Cecava, 1995;Mabjeesh et al., 1996). Although helpful, cannulation methods are expensive and labour-intensive and are subject to errors associated with sampling of digesta when indigestible markers are used to measure digesta flow (Stern et al., 1997). ...
... Studies conducted in situ, using the mobile bag technique, revealed no Novel approach to determine lysine availability differences in post-ruminal digestion of the SE, EP or LS products (Borucki Castro et al., 2007). In vivo studies with dairy cows comparing respectively SE with heated SBM (Mabjeesh et al., 1996), EP (Ludden and Cecava, 1995) or lignosulphonate SBM (Cleale et al., 1987;Mansfield and Stern, 1994) have also shown no differences in the post-ruminal digestion of protein. ...
... The average value for post-ruminal digestibility of Lys was 77%. Other authors have reported values of 83% and 84% for the intestinal digestibility of Lys in diets containing SE (Windschitl and Stern, 1988;Mabjeesh et al., 1996), and a value of 81% for diets containing LS (Windschitl and Stern, 1988). The lack of differences in digestible Lys (Table 4) between untreated (SE) and treated (EP, LS) SBM products indicates that, under the conditions of this study, the treatment of SBM did not increase Lys availability. ...
Lysine (Lys) availability in three different soya-bean meal (SBM) products was determined using the following techniques: whole body (WB) net flux of Lys, digestible Lys (duodenal flow × intestinal digestibility) and the plasma Lys response curve method of Rulquin and Kowalczyk (2003). Four multiparous Holstein cows (173 days in milk) were equipped with ruminal and duodenal cannulas and used in a 4 × 4 Latin square experiment with 14-day periods. The animals were fed either solvent-extracted SBM (SE), expeller-processed SBM (EP) or lignosulphonate-treated SBM (LS) at 23% of the diet dry matter (DM). The fourth treatment (SE70) consisted of a continuous infusion of Lys (70 g/day) into the omasum of cows fed the SE diet. Chromium(III) oxide was included as a digesta marker in order to determine the duodenal flow of amino acids (AA). On day 12 of each experimental period, six blood samples were collected to determine plasma Lys concentrations. Immediately after that, a pulse dose of L-[2-15N] Lys was administered in the jugular vein. Jugular blood samples were then collected at 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 13, 16, 19, 25 and 31 min after the injection to determine 15N Lys enrichment. On each of days 13 and 14, eight digesta samples were collected and pooled by period. Amongst the diets of SBM (SE, EP, LS), no differences were observed for duodenal Lys flow or digestible Lys. Duodenal flow of microbial N with SE was numerically higher, compared with EP and LS, indicating enhanced duodenal supply of microbial Lys for this diet, and this may have compensated for the additional Lys derived from undegradable protein in rumen-protected SBM products (EP and LS). The use of the plasma response curve method as well as the measurement of WB Lys flux also revealed no differences in Lys availability among the SBM products. The WB flux method resulted in 100% post-ruminal recovery of the Lys infused with diet SE70 compared with the control diet SE, which indicates that the method is reliable for determining Lys availability. The Lys flux approach not only allows for the estimation of intestinally available essential AA but also it avoids the use of cannulated animals.
... Soybean meal is the most common protein supplement in the US, and SBM has been used as the control supplement for most research trials; therefore, we summarized 15 metabolism trials (6,24,30,34,41,63,64,67,69,74,89,110,116,121,128) to evaluate the effects of replacing SBM with high RUP supplements on the flow of N fractions to the SI (Table 4). There were 29 direct comparisons with SBM in these 15 trials, and the results of those comparisons follow. ...
... jds 7458 Table 4 flow decreased (67,110) and, in 23 comparisons, was not affected. The mean Met flow was 50 g/d for SBM and 48 g/d for high RUP diets. ...
... Table 5 Blends of meat meal, CGM, BM, FtM, and FM increased total flows of EAA and Lys to the SI but did not improve the balance of Lys to Met from that occurring with SBM (34). When supplied as >4% of diet DM, FM consistently increased the proportion of Lys in EAA flowing to the duodenum compared with SBM (67,74,128), but not when supplied at <4% of diet DM (63,74). Also, FM had a positive effect on the proportion of Met in total EAA of duodenal digesta in 3 of 5 comparisons (63,67,74,128). ...
In order to integrate and analyze knowledge on the use of protein supplements and protein nutrition of lactating dairy cows, we compiled a review of 108 studies published throughout the world, but principally in the Journal of Dairy Science between 1985 and 1997. In 29 comparisons from 15 metabolism trials, soybean meal was replaced by high amounts of rumen undegradable protein (RUP) as a supplement; the benefits were not consistently observed for flow to the duodenum, essential amino acids, or lysine and methionine. High RUP diets resulted in decreased microbial protein synthesis in 76% of the comparisons. However, fish meal provided a good balance of lysine and methionine when calculated as a percentage of total essential amino acids. In 127 comparisons from 88 lactation trials that were published from 1985 to 1997, researchers studied the effects of replacing soybean meal with high RUP sources, such as heated and chemically treated soybean meal, corn gluten meal, distillers grains, brewers grains, blood meal, meat and bone meal, feather meal, or blends of these sources; milk yield was significantly higher in only 17% of the comparisons. Fish meal and treated soybean meal accounted for most of the positive effects on milk yield from RUP; corn gluten meal resulted in mostly negative results. The percentage of fat in milk was depressed more by fish meal than by other RUP sources. Protein percentage was decreased in 28 comparisons and increased in only 6 comparisons, probably reflecting the decrease in microbial protein synthesis, as was observed for diets high in RUP. The data strongly suggest that increased RUP per se in dairy cow diets, which often results in a decrease in RDP and a change in absorbed AA profiles, does not consistently improve lactational performance.
... Apparent N digestion in the intestines and total tract was unaltered by treatments (Table 6). Similar to results from this experiment, other researchers have reported no change in intestinal and (or) total tract digestibility of N when heated SSBM (Mabjeesh et al., 1996), NSBM (Cleale et al., 1987;Mansfield and Stern, 1994), or ESBM were compared with SSBM. ...
... Because the source of supplemental CP was essentially the only ingredient that varied in the diets, these results can be attributed to variations in DMI (Table 3) and in the AA composition of the soy protein supplements (Table 2). In other trials, the replacement of SSBM with heated SSBM (Mabjeesh et al., 1996), NSBM (Windschitl and Stern, 1988), or extruded soybeans (Stern et al., 1985) also altered AA intake. The source of soy protein did not influence the ruminal outflow of individual AA, total EAA, total NEAA, and total AA of microbial origin (Table 8), but affected markedly the ruminal escape of AA in the NANMN (Table 9) and NAN fractions (Table 10). ...
... With the exception of Met, Ser, and Tyr, partially replacing SSBM with NSBM improved or tended to improve (i.e., Ile, Lys, Val, and Gly) the intestinal supply of all other EAA and NEAA (Table 10). Similar improvements in the amount of AA that reached the small intestines of lactating cows were observed when heated and unheated SSBM were compared (Mabjeesh et al., 1996). However, Windschitl and Stern (1988) reported that only the passage to the duodenum of Glu and Pro increased when SSBM was replaced with xylose-or lignosulfonate-treated SSBM in the diet of dairy cows. ...
Four multiparous lactating Holstein cows that were fistulated in the rumen and duodenum and that averaged 205 d in milk were used in a 4 x 4 Latin square design to evaluate the practical replacement of solvent-extracted soybean meal (SSBM) with soy protein products of reduced ruminal degradability. On a dry matter (DM) basis, diets contained 15% alfalfa silage, 25% corn silage, 34.3 to 36.9% corn grain, 19.4% soy products, 18.2% crude protein, 25.5% neutral detergent fiber, and 35.3% starch. In the experimental diets, SSBM was replaced with expeller soybean meal (ESBM); heated, xylose-treated soybean meal (NSBM); or whole roasted soybeans (WRSB) to supply 10.2% of the dietary DM. Intakes of DM (mean = 20.4 kg/d), organic matter, and starch were unaffected by the source of soy protein. Similarly, true ruminal fermentation of organic matter and apparent digestion of starch in the rumen and total tract were not altered by treatments. Intake of N ranged from 567 (WRSB) to 622 g/d (ESBM), but differences among soy protein supplements were not significant. Compared with SSBM, the ruminal outflow of nonammonia N was higher for NSBM, tended to be higher for ESBM, and was similar for WRSB. The intestinal supply of nonammonia nonmicrobial N was higher for NSBM and WRSB and tended to be higher for ESBM than for SSBM. However, no differences were detected among treatments when the flow to the duodenum of nonammonia nonmicrobial N was expressed as a percentage of N intake or nonammonia N flow. The ruminal outflow of microbial N, Met, and Lys was not altered by the source of soy protein. Data suggest that partially replacing SSBM with ESBM, NSBM, or WRSB may increase the quantity of feed protein that reaches the small intestines of dairy cows. However, significant improvements in the supply of previously reported limiting amino acids for milk production, particularly of Met, should not be expected.
... Chalupa [122] studied that protein from the ration must escape rumen degradation and reach the small intestine for increased milk production. Applying heat to protein meals and whole seeds increases rumen undegradable protein [123]. ...
For dairy cattle, the period involving a shift from late pregnancy to early lactation termed transition or periparturient is an excruciating phase. Health-related disorders are likely to happen in this time frame. Timely postpartum and metabolic adjustments to this new physical state demands correct management strategies to fulfill the cow’s needs for a successful transition to this phase. Among the management strategies, one of the most researched methods for managing transition-related stress is nutritional supplementation. Dietary components directly or indirectly affect the expression of various genes that are believed to be involved in various stress-related responses during this phase. Nutrigenomics, an interdisciplinary approach that combines nutritional science with omics technologies, opens new avenues for studying the genome’s complicated interactions with food. This revolutionary technique emphasizes the importance of food-gene interactions on various physiological and metabolic mechanisms. In animal sciences, nutrigenomics aims to promote the welfare of livestock animals and enhance their commercially important qualities through nutritional interventions. To this end, an increasing volume of research shows that nutritional supplementation can be effectively used to manage the metabolic stress dairy cows undergo during the transition period. These nutritional supplements, including polyunsaturated fatty acids, vitamins, dietary amino acids, and phytochemicals, have been shown to modulate energy homeostasis through different pathways, leading to addressing metabolic issues in transition cows.
... This is reflected in the reduced CCC and positive slope bias as compared with the kinetic models (Table 2). For example, there was little difference in predicted RUP between soybean meal and heat-treated soybean meal (data not shown), despite quite substantial differences in rates of degradation (Driver et al., 1990), the expected extent of degradation based on the kinetic model, and observed differences in NANMN flow for dairy cows fed heattreated soybean meal compared with soybean meal (Mabjeesh et al., 1996). Based on these results, none of the simpler models yielded robust performance despite addressing mean and slope bias, and one must conclude that the kinetic model is a better representation than a static model. ...
The objectives of the present work were (1) to identify the cause of the linear bias in predictions of rumen-undegradable protein (RUP) content of feeds, and devise methods to remove the bias from prediction equations, and (2) to further explore the impact of rumen-degradable protein (RDP) on microbial N (MiN) outflow from the rumen. The kinetic model used by NRC, 2001 , which is based on protein fractionation and rates of degradation (Kd) and passage (Kp), displays considerable slope bias (−0.30 kg/kg), indicating parameter or structural problems. Regressing Kp by feed class and a static adjustment factor for the in situ–derived Kd on observed RUP flows completely resolved the slope bias problem, and the model performed significantly better than models using unadjusted Kd and marker-based Kp. The Kd adjustment was 3.82%/h, which represents approximately a 50% increase in rates of degradation over the in situ values, indicating that in situ analyses severely underestimate true rates of protein degradation. The Kp for concentrate-derived protein was 5.83%/h, which was slightly less than the marker-predicted rate of 6.69%/h. However, the derived forage protein rate was 0.49%/h, which was considerably less than the marker-based rate of 5.07%/h. Compartmental analysis of data from a single study corroborated the regression analysis, indicating that a 25% reduction in the overall passage rate and an 87% increase in the rate of degradation were required to align ruminal N pool sizes and the extent of protein degradation with the observed data. Therefore, one must conclude that both the in situ–derived degradation rates and the marker-based particle passage rates are biased relative to protein passage and cannot be used directly to predict RUP outflow from the rumen. The effects of RDP supply on microbial nitrogen (MiN) flow were apparent when intakes of individual nutrients were offered but not when DM intake and individual nutrient concentrations were offered, due to collinearity problems. Microbial N flow from the rumen was found to be linearly related to ruminally degraded starch, ruminally degraded neutral detergent fiber (NDF), RDP, and forage NDF intakes; and quadratically related to residual OM intake. More complicated models containing 2- and 3-way interactions among nutrients were also supported by the data. Independent MiN responses to RDP, ruminally degraded starch, and ruminally degraded NDF aligned with the expected responses to each of those nutrients. Nonlinear representations of MiN were found to be inferior to the linear models. Despite using unbiased predictions of RUP and MiN as drivers of AA flows, predictions of Arg, His, Ile, and Lys flow exhibited linear slope bias relative to the observed data, indicating that representations of the AA composition of the proteins may be biased or the observed data are biased. This is an improvement over the NRC, 2001 predictions, where bias adjustments were required for all of the essential AA. Despite the bias for 4 AA flows, the revised prediction system was a substantial improvement over the prior work.
... This is reflected in the reduced CCC and positive slope bias as compared with the kinetic models (Table 2). For example, there was little difference in predicted RUP between soybean meal and heat-treated soybean meal (data not shown), despite quite substantial differences in rates of degradation (Driver et al., 1990), the expected extent of degradation based on the kinetic model, and observed differences in NANMN flow for dairy cows fed heattreated soybean meal compared with soybean meal (Mabjeesh et al., 1996). Based on these results, none of the simpler models yielded robust performance despite addressing mean and slope bias, and one must conclude that the kinetic model is a better representation than a static model. ...
The objectives of the present work were (1) to identify the cause of the linear bias in predictions of rumen-undegradable protein (RUP) content of feeds, and devise methods to remove the bias from prediction equations, and (2) to further explore the impact of rumen-degradable protein (RDP) on microbial N (MiN) outflow from the rumen. The kinetic model used by NRC (2001), which is based on protein fractionation and rates of degradation (Kd) and passage (Kp), displays considerable slope bias (−0.30 kg/kg), indicating parameter or structural problems. Regressing Kp by feed class and a static adjustment factor for the in situ–derived Kd on observed RUP flows completely resolved the slope bias problem, and the model performed significantly better than models using unadjusted Kd and marker-based Kp. The Kd adjustment was 3.82%/h, which represents approximately a 50% increase in rates of degradation over the in situ values, indicating that in situ analyses severely underestimate true rates of protein degradation. The Kp for concentrate-derived protein was 5.83%/h, which was slightly less than the marker-predicted rate of 6.69%/h. However, the derived forage protein rate was 0.49%/h, which was considerably less than the marker-based rate of 5.07%/h. Compartmental analysis of data from a single study corroborated the regression analysis, indicating that a 25% reduction in the overall passage rate and an 87% increase in the rate of degradation were required to align ruminal N pool sizes and the extent of protein degradation with the observed data. Therefore, one must conclude that both the in situ–derived degradation rates and the marker-based particle passage rates are biased relative to protein passage and cannot be used directly to predict RUP outflow from the rumen. The effects of RDP supply on microbial nitrogen (MiN) flow were apparent when intakes of individual nutrients were offered but not when DM intake and individual nutrient concentrations were offered, due to collinearity problems. Microbial N flow from the rumen was found to be linearly related to ruminally degraded starch, ruminally degraded neutral detergent fiber (NDF), RDP, and forage NDF intakes; and quadratically related to residual OM intake. More complicated models containing 2- and 3-way interactions among nutrients were also supported by the data. Independent MiN responses to RDP, ruminally degraded starch, and ruminally degraded NDF aligned with the expected responses to each of those nutrients. Nonlinear representations of MiN were found to be inferior to the linear models. Despite using unbiased predictions of RUP and MiN as drivers of AA flows, predictions of Arg, His, Ile, and Lys flow exhibited linear slope bias relative to the observed data, indicating that representations of the AA composition of the proteins may be biased or the observed data are biased. This is an improvement over the NRC (2001) predictions, where bias adjustments were required for all of the essential AA. Despite the bias for 4 AA flows, the revised prediction system was a substantial improvement over the prior work.
... Finally, the protein digestibility of feed ingredients is likely not consistent under different feeding conditions, such as very high or low CP and energy intakes (Yang and Beauchemin, 2004). In addition, ingredient source and degradability of dietary CP are also factors that may introduce variation among sources of a common ingredient (Prange et al., 1984;Mabjeesh et al., 1996;Kleinschmit et al., 2007). Therefore, additional work is required to assess the range in availabilities from different sources of an ingredient with different feeding conditions (e.g., high and low forage), and to further evaluate in situ and in vitro methods, compared with in vivo measurement, if we are to develop a real-time system that can be used by industry. ...
Nitrogen efficiency in dairy cows can be improved by more precisely supplying essential amino acids (EAA) relative to animal needs, which requires accurate estimates of the availability of individual EAA from feedstuffs. The objective of this study was to determine EAA availability for 7 feed ingredients. Seven heifers (258 ± 28 kg BW) were randomly chosen and assigned to 8 treatment sequences in a 7 × 8 incomplete Latin square design. Treatments were a basal diet (BD), and 10% (on a dry matter basis) of BD replaced by corn silage (CS), grass hay (GH), alfalfa hay (AH), dried distillers grain (DDGS), soybean hulls (SH), wet brewers grain (BG), or corn grain (CG). Total plasma AA entry rates were estimated for each EAA within each diet by fitting a 4-pool dynamic model to observed plasma, 13C AA enrichment resulting from a 2-h constant infusion of a 13C algal AA mixture. Individual EAA availability from each test ingredient was determined by regression of entry rates for that AA on crude protein intake for each ingredient. The derived plasma total EAA entry rates for corn silage, grass hay, alfalfa hay, dried distillers grain, soyhulls, brewers grain, and corn grain were 30.6 ± 3.4, 27.4 ± 3.2, 31.3 ± 3.4, 37.2 ± 3.2, 26.4 ± 3.2, 37.8 ± 3.2, and 33.5 ± 3.2% (±standard error) of EAA from each ingredient, respectively. Using the previous estimate of 8.27% EAA utilization by splanchnic tissues during first pass, total rumen-undegradable protein EAA absorbed from the gut lumen was 33.4, 29.9, 34.1, 40.6, 28.8, 41.2, and 36.5% of the EAA in each ingredient respectively.
... However, showed that Lys flow for soy RUP was greater than for corn RUP, and milk protein yield was slightly higher for soy RUP. Given its high Lys and RUP (72-79%, Jahani-Moghadam et al. 2009), feeding XSBM can increase intestinal Lys flow (Mabjeesh et al. 1996) and milk protein synthesis . ...
This experiment was performed to investigate whether feeding xylose-treated soybean meal (XSBM) or corn gluten meal (CGM) is economically better under field conditions. Ninety-four multiparous early lactat-ing Holstein cows (55±5 days in milk and 2.82±0.41 body condition score) were used in a completely ran-domized design. Cows were randomly assigned to one of two treatments: XSBM or CGM as the main ru-men undegradable protein source in the diet. Dry matter intake (DMI), milk yield and fat corrected milk (FCM) were not affected by treatments. A tendency was detected for higher FCM: DMI (1.57 vs. 1.47) and income:cost (1.97 vs. 1.83) in CGM treatment. Milk urea nitrogen was greater (15.89 vs. 15.16 mg/dL) in the XSBM group. Plasma glucose, non-esterified fatty acid, beta-hydroxy butyric acid and albumin were not different between treatments. The results showed that under field conditions and feed ingredients used in this experiment, using CGM was economically beneficial during early lactation, which is in contrast with traditional beliefs.
... Hence, RUP sources low in Lys and Met might result in no increase or a decrease in milk yield and composition. Shroeder and Gagliostro (2000) reported that milk and milk protein yields were increased by fishmeal compared to sunflower meal ( In contrast, replacing a RDP source for RUP source resulted in no effect on DMI and N intake in several studies (Armentano et al., 1986;Chan et al., 1997;Mabjeesh et al., 1996). Microbial N flow to the small intestine was decreased (P < .05) ...
... However, showed that Lys flow for soy RUP was greater than for corn RUP, and milk protein yield was slightly higher for soy RUP. Given its high Lys and RUP (72-79%, Jahani-Moghadam et al. 2009), feeding XSBM can increase intestinal Lys flow (Mabjeesh et al. 1996) and milk protein synthesis . ...
Abstract
This experiment was performed to investigate whether feeding xylose-treated soybean meal (XSBM) or corn gluten meal (CGM) is economically better under field conditions. Ninety-four multiparous early lac tating Holstein cows (55 ± 5 day in milk and 2.82 ± 0.41
body condition score) were used in a completely randomized design. Cows were randomly assigned to one of two treatments: XSBM or CGM as the main rumen undegradable protein (RUP) source in the diet. Dry matter intake (DMI), milk production and fat corrected milk (FCM) were not affec ted by treatments. A tend ency was detected for higher fat corrected milk:DMI (1.57 vs. 1.47) and income:cost (1.97 vs. 1.83) in CGM treat ment. Milk urea nitrogen was greater (15.89 vs. 15.16 mg/dl) in the soy RUP group. Plasma glucose, non-esterified fatty acid, beta-hydroxy butyric acid and albumin were not different between treatments. These results show that under field conditions and feed ingredients used here, using CGM is more economically beneficial during early lactation, which is
in contrast with t raditional beliefs.
Keywords : early lactation, benefit, treated soybean meal, corn gluten meal, performance
... 80(11):2901-2906.Figure 2. Residual errors for predictions of non-ammonia, non-microbial nitrogen (NANMN) 1029 versus the calculated rate constant for degradation of insoluble protein in the rumen (eqn. [4]).Aldrich et al., 1993) (Klusmeyer et al., 1991a) (Pires et al., 1997) (Armentano et al., 1986) (Klusmeyer et al., 1991b) (Poore et al., 1993) (Blauwiekel et al., 1997) (Kung et al., 1983) (Prange et al., 1984) (Calsamiglia et al., 1995) (Lu et al., 1988) (Price et al., 1988) (Cameron et al., 1991) () (Putnam et al., 1997) (Chan et al., 1997) () () (Christensen et al., 1993) (Lynch et al., 1991) (Robinson et al., 1997) (Cunningham et al., 1994) (Mabjeesh et al., 1996) (Santos et al., 1984) (Cunningham et al., 1996) (Mabjeesh et al., 1997) (Sarwar et al., 1991) (Doreau et al., 1991) (Mansfield and Stern, 1994) (Schwab et al., 1992a) (Erasmus et al., 1994) (McCarthy et al., 1989) (Schwab et al., 1992b) (Espindola et al., 1997) (Merchen and Satter, 1983) (Seymour et al., 1992) (Feng et al., 1993) (Murphy et al., 1987) (Song and Kennelly, 1989) (Herrera-Saldana et al., 1990) (Narasimhalu et al., 1989) (Stokes et al., 1991) (Horner et al., 1988) (Ohajuruka et al., 1991) (Tice et al., 1993) (Joy et al., 1997) (Oliveira et al., 1995) (Waltz et al., 1989) (Kalscheur et al., 1997a) (O'Mara et al., 1997) (Windschitl and Stern, 1988) (Kalscheur et al., 1997b) (Overton et al., 1995) (Yang et al., 1997) (King et al., 1990) (Pantoja et al., 1995) (Yoon and Stern, 1996) (Klusmeyer et al., 1990) (Pena et al., 1986) (Zerbini et al., 1988) (Zhu et al., 1997) 1037 1038Table 2. A summary of the data contained in references listed in 1039 ...
The Molly cow model represents nutrient digestion and metabolism based on a mechanistic representation of the key biological elements. Digestive parameters were derived ad hoc from literature observations or were assumed. Preliminary work determined that several of these parameters did not represent the true relationships. The current work was undertaken to derive ruminal and postruminal digestive parameters and to use a meta-approach to assess the effects of interactions among nutrients and identify areas of model weakness. Model predictions were compared with a database of literature observations containing 233 treatment means. Mean square prediction errors were assessed to characterize model performance. Ruminal pH prediction equations had substantial mean bias, which caused problems in fiber digestion and microbial growth predictions. The pH prediction equation was reparameterized simultaneously with the several ruminal and postruminal digestion parameters, resulting in more realistic parameter estimates for ruminal fiber digestion, and moderate reductions in prediction errors for pH, neutral detergent fiber, acid detergent fiber, and microbial N outflow from the rumen; and postruminal digestion of neutral detergent fiber, acid detergent fiber, and protein. Prediction errors are still large for ruminal ammonia and outflow of starch from the rumen. The gain in microbial efficiency associated with fat feeding was found to be more than twice the original estimate, but in contrast to prior assumptions, fat feeding did not exert negative effects on fiber and protein degradation in the rumen. Microbial responses to ruminal ammonia concentrations were half saturated at 0.2 mM versus the original estimate of 1.2 mM. Residuals analyses indicated that additional progress could be made in predicting microbial N outflow, volatile fatty acid production and concentrations, and cycling of N between blood and the rumen. These additional corrections should lead to an even more robust representation of the effects of dietary nutrients on ruminal metabolism and nutrient absorption, of animal performance, and the environmental impact of dairy production.
... A 0 . 70 0 . 059 0 . 56 0 . 81 Total AA 0 . 70 0 . 056 0 . 56 0 . 82 1 Data from Hvelplund and Möller ( 1976 ) , Santos et al . ( 1984 ) , Stern et al . ( 1985 ) , Garrett et al . ( 1987 ) , Waltz et al . ( 1989 ) , Beever et al . ( 1990 ) , Cecava et al . ( 1990 ) , Hussein et al . ( 1991 ) , Keery et al . ( 1993 ) , Krastanova et al . ( 1995 ) , Mabjeesh et al . ( 1996 ) and Kowalczyk and Zebrowska ( 1998 ) ...
... Total flow of N through the duodenum was not different across dietary treatments though there was less N in the liquid fraction when cows were fed the BASE diet as compared to the other three diets (P = 0.006; Table 3-3). Duodenal total CP flow was lower when cows were fed diets supplemented with animal proteins versus plant proteins (Mabjeesh et al., 1996) but not when cows were fed high and low amounts of rumen-available protein supplemented to either a high or low rumenavailable non structural carbohydrate diet (Aldrich et al., 1993). In the duodenum, ...
Thesis research directed by: Animal Sciences. Title from t.p. of PDF. Thesis (Ph. D.) -- University of Maryland, College Park, 2006. Includes bibliographical references. Text.
... In corn-based diets (forage and grain), duodenal Lys rather than Met is more likely to be the first AA limiting milk protein synthesis (Schwab et al., 1992). Given its high Lys, feeding XSBM can increase duodenal Lys flow (Mabjeesh et al., 1996) and milk protein synthesis . Based on our in situ data, rapidly degradable DM and CP were lower, and the potentially degradable fractions were degraded more slowly in XSBM than in SBM. ...
Effects of different dietary rumen undegradable (RUP) to degradable (RDP) protein ratios on ruminal nutrient degradation, feed intake, blood metabolites and milk production were determined in early lactation cows. Four multiparous (43 ± 5 days in milk) and four primiparous (40 ± 6 days in milk) tie-stall-housed Holstein cows were used in a duplicated 4 × 4 Latin square design with four 21-day periods. Each period had 14-day of adaptation and 7-day of sampling. Diets contained on a dry matter (DM) basis, 23.3% alfalfa hay, 20% corn silage and 56.7% concentrate. Cows were first offered alfalfa hay at 7:00, 15:00 and 23:00 hours, and 30 min after each alfalfa hay delivery were offered a mixture of corn silage and concentrate. Treatments were diets with RUP:RDP ratios of (i) 5.2:11.6 (control), (ii) 6.1:10.6, (iii) 7.1:9.5 and (iv) 8.1:8.5, on a dietary DM% basis. Different RUP:RDP ratios were obtained by partial and total replacement of untreated soybean meal (SBM) with xylose-treated SBM (XSBM). In situ study using three rumen-cannulated non-lactating cows showed that DM and crude protein (CP) of SBM had greater rapidly degradable fractions. The potentially degradable fractions were degraded more slowly in XSBM. Treatment cows produced greater milk, protein, lactose, solids-non-fat and total solids than control cows. Increasing RUP:RDP reduced blood urea linearly. Feed costs dropped at RUP:RDP ratios of 6.1:10.6 and 7.1:9.5, but not at 8.1:8.5, compared with the 5.2:11.6 ratio. Intake of DM and CP, rumen pH, blood glucose, albumin and total protein, faecal and urine pH, changes in body weight and body condition score, and milk lactose and solids-non-fat percentages did not differ among treatments. Results provide evidence that increasing dietary RUP:RDP ratio from 5.2:11.6 to 7.1:9.5 optimizes nitrogen metabolism and milk production and reduces feed costs in early lactation cows. Reduced blood urea suggests reprodutive benefits.
... Similar ruminal NDF digestibility among treatments suggests that fiber fermentation conditions were not greatly deteriorated by the addition of 1.5 kg of starch into the rumen. Normal microbial efficiency values were found when apparent rumen-degradable OM was 7 to 8 kg/d (Mabjeesh et al., 1996), similar to the ruminal digestion of OM in the current study (Table 2). Intake of CP was decreased in RS by 0.5 kg/d, whereas CP flow to the duodenum was similar to CONT (Table 4), indicating improved ruminal microbial synthesis in RS-treated cows. ...
The effect of infusing similar energy equivalents of starch into the rumen, or starch or oil into the abomasum was studied in four midlactation cows in a 4 x 4 Latin square design experiment; controls were ruminally infused with water. Cows were fitted with cannulas in the rumen, abomasum, and ileum, and nutrient digestion in the rumen and small intestine was evaluated with Cr as a digesta marker. Ruminal infusions of starch, or abomasal infusions of starch or oil, were associated with a decrease in voluntary feed organic matter intake. Overall energy intake was reduced in oil-infused, but not in starch-infused cows. Nonstructural carbohydrate digestibility in the rumen and in the small intestine was similar among treatments. In abomasally infused cows 3.4 kg/d of nonstructural carbohydrates was apparently digested in the small intestine. Milk production was reduced in oil-infused cows, but the efficiency of milk energy and protein yield was unaffected by treatments. Plasma glucose, insulin, and IGF-1 concentration, mammary glucose extraction rate, rumen ammonia and plasma urea, and arterial and mammary extraction rate of amino acids were all similar among treatments. Large quantities of starch can be digested in the rumen or small intestine of dairy cows. There appear to be no metabolic advantage to increasing the supply of starch to the rumen or the abomasum of mid-lactation dairy cows maintained on highly concentrated diets and exhibiting a positive energy balance.
Milk is Nature's most nearly perfect food and for good reason. Colostrum the first secretion may contain as high as 24% solids and, provides immunoglobulins for the newborn to provide protection against disease until the immune system begins to produce antibodies against the microbial population in its environment. In 1850 average annual production per cow was 57 kg. The dramatic change was the commitment by the United States government beginning in 1862 with the creation of Land Grant Colleges and Universities. Their mission was teaching, research and, transfer of research findings to producers. Annual milk production per cow in 2019 was 10,500 kg, a 184-fold increase. In 2018, a cow in Wisconsin produced over 35,000 kg on milk in 365 days.
The objective of this work was to update and evaluate predictions of essential AA (EAA) outflows from the rumen. The model was constructed based on previously derived equations for rumen-undegradable (RUP), microbial (MiCP), and endogenous (EndCP) protein outflows from the rumen, and revised estimates of ingredient composition and EAA composition of the protein fractions. Corrections were adopted to account for incomplete recovery of EAA during 24-h acid hydrolysis. The predicted ruminal protein and EAA outflows were evaluated against a data set of observed values from the literature. Initial evaluations indicated a minor mean bias for non-ammonia, non-microbial nitrogen flow ([RUP + EndCP]/6.25) of 16 g of N per day. Root mean squared errors (RMSE) of EAA predictions ranged from 26.8 to 40.6% of observed mean values. Concordance correlation coefficients (CCC) of EAA predictions ranged from 0.34 to 0.55. Except for Leu, all ruminal EAA outflows were overpredicted by 3.0 to 32 g/d. In addition, small but significant slope biases were present for Arg [2.2% mean squared error (MSE)] and Lys (3.2% MSE). The overpredictions may suggest that the mean recovery of AA from acid hydrolysis across laboratories was less than estimates encompassed in the recovery factors. To test this hypothesis, several regression approaches were undertaken to identify potential causes of the bias. These included regressions of (1) residual errors for predicted EAA flows on each of the 3 protein-driven EA flows, (2) observed EAA flows on each protein-driven EAA flow, including an intercept, (3) observed EAA flows on the protein-driven EAA flows, excluding an intercept term, and (4) observed EAA flows on RUP and MiCP. However, these equations were deemed unsatisfactory for bias adjustment, as they generated biologically unfeasible predictions for some entities. Future work should focus on identifying the cause of the observed prediction bias.
The first issue of the Journal of Dairy Science in 1917 opened with the text of the speech by Raymond A. Pearson, president of the Iowa State College of Agriculture, at the dedication of the new dairy building at the University of Nebraska (J. Dairy Sci. 1:4–18, 1917). Fittingly, this was the birth of a new research facility and more importantly, the beginning of a new journal devoted to the sciences of milk production and manufacture of products from milk. Metabolic modifiers of dairy cow metabolism enhance, change, or interfere with normal metabolic processes in the ruminant digestive tract or alter postabsorption partitioning of nutrients among body tissues. Papers on metabolic modifiers became more frequent in the journal around 1950. Dairy farming changed radically between 1955 and 1965. Changes in housing and feeding moved more cows outside, and cows and heifers in all stages of lactation, including the dry period, were fed as a single group. Rations became wetter with the shift to corn silage as the major forage in many rations. Liberal grain feeding met the requirements of high-producing cows and increased production per cow but introduced new challenges; for example, managing and feeding cows as a group. These changes led to the introduction of new strategies that identified and expanded the use of metabolic modifiers. Research was directed at characterizing the new problems for the dairy cow created by group feeding. Metabolic modifiers went beyond feeding the cow and included environmental and housing factors and additives to reduce the incidence and severity of many new conditions and pathologies. New collaborations began among dairy cattle specialties that broadened our understanding of the workings of the cow. The Journal of Dairy Science then and now plays an enormously important role in dissemination of the findings of dairy scientists worldwide that address existing and new technologies.
The objective of this study was to investigate the flow and absorption of amino acids (AA) in steers fed diets supplemented with different protein sources. Twenty-one Holstein steers averaging eight months of age and 187 kg of body weight were used. Animals were fitted with abomasal caanulas and fed diets with a forage to concentrate ratio of 40:60. The experimental diets contained Rhodes grass hay, corn, molasses, minerals, and one of the following protein sources: cottonseed meal, yeast, or urea. Animals were assigned to treatments in a completely randomized design with three protein sources and seven replicates per treatment. Each experimental period lasted 17 days with 10 days for diet adaptation and seven days for sample collection. Samples of abomasal digesta were collected every 28 h while those of feces twice a day during the sampling period. The abomasal flow of AA (g/d) and the AA composition of abomasal and fecal samples were significantly affected by protein source. However, no protein source effect was observed for AA digestibility. The abomasal availability and intestinal absorption of AA were lower than expected probably because animals were feed restricted. It can be concluded that AA availability and composition were affected by the different protein sources fed to steers in this trial.
The experiment was carried out on 10 bulls of about 120 kg live weight equipped with rumen cannulas and re-entrant cannulas in the proximal duodenum and terminal ileum. The bulls were given a diet of maize whole plant meal, potato starch and mineral mixture. The diet was supplemented for group I with groundnut oilmeal (60% of dietary N), for group II with groundnut oilmeal (10.5% dietary N) and urea (48% of dietary N), and for group III with urea (58% dietary N). Diets I, II and III contained, according to the INRA system, 15% CP in DM; 234, 196, 186 g PDIN; 227, 158, 145 g PDIE, and 2.14, 2.11, 2.11 UFV, respectively. Daily feed intake was 2.25 kg. The ammonia-N level in the rumen fluid 2 h after feeding was 8.2, 15.1 and 24.5 mg/100 ml in animals of groups I, II and III, respectively. The amount of N entering the duodenum was 20.1; 22.1 and 18.0 g, leaving the ileum 9.7, 10.4 and 7.3 g/day/kg of feed intake, in the respective groups. The apparent duodenal-N absorption from the small intestine was 52, 53 and 59%, respectively. Total amino acids (g/day/kg feed) ingested with feed equalled 128, 62 and 49; entering the duodenum 107, 113 and 92; leaving the ileum 43, 48 and 32; absorbed from the small intestine 64, 65 and 60 in groups I, II and III, respectively. The apparent intestinal absorption of most amino acids entering the duodenum was from 50 to 70% in all groups, but absorption of cysteine was markedly lower, 25-40%. The amount of lysine absorbed from the small intestine in group I was similar to the amount ingested, but exceeded this amount by 2.4 and 3 times in groups II and III. Absorption of methionine was two times higher, indicating considerable conversion of dietary N in group II and III into microbial amino acids.
In the first of two experiments, four rumen cannulated wethers were used to determine the extent of rumen protein degradation in soyabean meal (SBM), rapeseed meal (RSM) and extruded field bean seeds (EFB), using the in sacco method. Rumen non-degradable N in SBM, RSM and EFB of total-N was 38, 29 and 48%, respectively. In the second experiment, four rams with cannulas in the duodenum were fed isoenergetic total mixed rations (TMR) containing similar amounts of protein truly digestible in the small intestine (PDI). TMR consisted of meadow hay and concentrate (50:50, DM basis) in which SBM, SBM+RSM and SBM+EFB were the main sources of protein. The highest, statistically significant (P<0.05) methionine and cystine concentrations in the duodenal digesta were found in sheep fed SBM+RSM diet, while the lowest - in those fed SBM+EFB diet Significantly higher (P<0.05) flows of total N (33.49 g/day), non-ammonia N (33.08 g/day) and total amino acid (197.7 g/d) were observed in sheep fed rations with SBM + EFB.
This experiment was performed in a completely randomized design with four treatments and nine replicates per treatments, using of 36 Moghani male lambs. Four diets containing 0, 7, 14 and 21 percent (dry matter basis) of processed broiler litter (PBL) were used. Results showed that voluntary feed intake, average daily gain and total body weight gain were not influenced (P>0.05) by the experimental diets. Digestibility of DM and NDF decreased linearly (P<0.05) while no differences (P>0.05) were detected in OM and CP digestibility by inclusion of PBL in the diets. The Ruminal acetate concentration decreased but ammonia increased linearly (P<0.05) as the rate of PBL enhanced in the diet, however no differences (P>0.05) were obtained for the other metabolites between the animals received different diets. Blood urea-nitrogen increased linearly (P<0.05) by increasing of PBL in the diet, but other blood metabolites were not influenced (P>0.05) by the experimental rations. Results of current study indicated that feeding PBL in the diet of Moghani lambs up to 21percent, did not affect the nutrients intake and growth performance but decreased digestibility of DM and NDF and ruminal acetate concentration. In Addition, feed cost per unit of live weight gain was decreased (P<0.05) by inclusion of PBL in the ration. It is concluded that processed broiler litter could be used up to 21 percent of the diet for fattening lambs.
The objective of this study was to investigate the flow and absorption of amino acids (AA) in steers fed diets supplemented with different protein sources. Twenty-one Holstein steers averaging eight months of age and 187 kg of body weight were used. Animals were fitted with abomasal caanulas and fed diets with a forage to concentrate ratio of 40:60. The experimental diets contained Rhodes grass hay, corn, molasses, minerals, and one of the following protein sources: cottonseed meal, yeast, or urea. Animals were assigned to treatments in a completely randomized design with three protein sources and seven replicates per treatment. Each experimental period lasted 17 days with 10 days for diet adaptation and seven days for sample collection. Samples of abomasal digesta were collected every 28 h while those of feces twice a day during the sampling period. The abomasal flow of AA (g/d) and the AA composition of abomasal and fecal samples were significantly affected by protein source. However, no protein source effect was observed for AA digestibility. The abomasal availability and intestinal absorption of AA were lower than expected probably because animals were feed restricted. It can be concluded that AA availability and composition were affected by the different protein sources fed to steers in this trial.
This trial was designed to investigate effects of the amount of dietary undegradable crude protein (CP) and the ratio of degradable organic matter to degradable CP in the diets of high-yielding dairy cows on milk yield, energy balance and fertility during the first three months postpartum. Forty-five Israeli Holstein cows were assigned to three dietary treatments at 2 d postpartum. Dietary treatments were (1) 16.7% CP, of which 32% was undegradable (control); (2) 16.7% CP, of which 38% was undegradable; and (3) 18.0% CP, of which 35% was undegradable. Corn gluten meal (CGM) was added to diets 2 and 3 in order to increase undegradability. Cows were fed in groups, and diets were offered as a total mixed ration. Intakes of dry matter (DMI) and CP (kg/d) were 23.8 and 3.975, 21.4 and 3.574, and 20.4 and 3.672, for cows on diets 1, 2 and 3, respectively. No significant differences among the three treatments were found for milk yield, milk protein concentration, milk fat, or protein and lactose yields. Control cows lost 35.0 kg of body weight (BW) during the first 27.2 d postpartum, and then started gaining weight. At approximately day 70 the control cows attained their calving weight. Cows on diets 2 and 3 lost 55 kg of BW during 45 d postpartum and, by the end of the trial, these cows still had not attained their calving weight. Change in body condition score (BCS) during the experimental period revealed the same trends. Mean concentrations (mg/100 ml) of ammonia N in ruminal fluids and concentrations of plasma urea N were 14.0 and 20.3, 12.7 and 21.2, and 14.7 and 21.3 for cows on diets 1, 2 and 3, respectively. No significant differences among treatments were detected for any reproduction parameter. It was concluded that the differences between control cows and cows on diets 2 and 3 in DMI, BW and BCS during the first period postpartum cannot be attributed to the level of dietary undegradable CP only but to a more specific effect of CGM.
The objective of this analysis was to compare the rumen submodel predictions of 4 commonly used dairy ration programs to observed values of duodenal flows of crude protein (CP), protein fractions, and essential AA (EAA). The literature was searched and 40 studies, including 154 diets, were used to compare observed values with those predicted by AminoCow (AC), Agricultural Modeling and Training Systems (AMTS), Cornell-Penn-Miner (CPM), and National Research Council 2001 (NRC) models. The models were evaluated based on their ability to predict the mean, their root mean square prediction error (RMSPE), error bias, and adequacy of regression equations for each protein fraction. The models predicted the mean duodenal CP flow within 5%, with more than 90% of the variation due to random disturbance. The models also predicted within 5% the mean microbial CP flow except CPM, which overestimated it by 27%. Only NRC, however, predicted mean rumen-undegraded protein (RUP) flows within 5%, whereas AC and AMTS underpredicted it by 8 to 9% and CPM by 24%. Regarding duodenal flows of individual AA, across all diets, CPM predicted substantially greater (>10%) mean flows of Arg, His, Ile, Met, and Lys; AMTS predicted greater flow for Arg and Met, whereas AC and NRC estimations were, on average, within 10% of observed values. Overpredictions by the CPM model were mainly related to mean bias, whereas the NRC model had the highest proportion of bias in random disturbance for flows of EAA. Models tended to predict mean flows of EAA more accurately on corn silage and alfalfa diets than on grass-based diets, more accurately on corn grain-based diets than on non-corn-based diets, and finally more accurately in the mid range of diet types. The 4 models were accurate at predicting mean dry matter intake. The AC, AMTS, and NRC models were all sufficiently accurate to be used for balancing EAA in dairy rations under field conditions.
Microbial fermentation of carbohydrates in the hindgut of dairy cattle is responsible for 5 to 10% of total-tract carbohydrate digestion. When dietary, animal, or environmental factors contribute to abnormal, excessive flow of fermentable carbohydrates from the small intestine, hindgut acidosis can occur. Hindgut acidosis is characterized by increased rates of production of short-chain fatty acids including lactic acid, decreased digesta pH, and damage to gut epithelium as evidenced by the appearance of mucin casts in feces. Hindgut acidosis is more likely to occur in high-producing animals fed diets with relatively greater proportions of grains and lesser proportions of forage. In these animals, ruminal acidosis and poor selective retention of fermentable carbohydrates by the rumen will increase carbohydrate flow to the hindgut. In more severe situations, hindgut acidosis is characterized by an inflammatory response; the resulting breach of the barrier between animal and digesta may contribute to laminitis and other disorders. In a research setting, effects of increased hindgut fermentation have been evaluated using pulse-dose or continuous abomasal infusions of varying amounts of fermentable carbohydrates. Continuous small-dose abomasal infusions of 1 kg/d of pectin or fructans into lactating cows resulted in decreased diet digestibility and decreased milk fat percentage without affecting fecal pH or VFA concentrations. The decreased diet digestibility likely resulted from increased bulk in the digestive tract or from increased digesta passage rate, reducing exposure of the digesta to intestinal enzymes and epithelial absorptive surfaces. The same mechanism is proposed to explain the decreased milk fat percentage because only milk concentrations of long-chain fatty acids were decreased. Pulse-dose abomasal fructan infusions (1 g/kg of BW) into steers resulted in watery feces, decreased fecal pH, and increased fecal VFA concentrations, without causing an inflammatory response. Daily 12-h abomasal infusions of a large dose of starch (~4 kg/d) have also induced hindgut acidosis as indicated by decreased fecal pH and watery feces. On the farm, watery or foamy feces or presence of mucin casts in feces may indicate hindgut acidosis. In summary, hindgut acidosis occurs because of relatively high rates of large intestinal fermentation, likely due to digestive dysfunction in other parts of the gut. A better understanding of the relationship of this disorder to other animal health disorders is needed.
A feeding trial of 120 days duration was conducted to study the effect of replacing 20 and 25 % of camel ration by poultry litter (PL) on the performance and some blood biochemical parameters. Fifteen healthy one–humped camels were allotted into three groups (5 animals / group). The first group was fed a basal ration and considered as control, while the second and third groups were fed rations in which poultry litter replaced 20 and 25 % of the basal ration. There was no significant differences in the dry matter intake and digestion coefficients of dry matter and ether extract between the different groups and camels fed on ration containing poultry litter had significantly (P < 0.05) decreased daily gain and feed conversion compared to the control. The apparent digestibility of crude protein by camels increased with 20 % poultry litter in the ration compared with other treatments. Digestibility of crude fibre was higher in rations containing poultry litter compared to control one. No significant differences were observed in blood biochemical parameters except urea and uric acid concentrations were significantly (P < 0.05) higher in the serum of animals fed on poultry litter.In general, it could be concluded that, dried poultry litter can be utilized efficiently and safely in rations of camels up to a level of 25 % without adversely effect on performance.
This study analyzed the relationships among the effective degradabilities of organic matter (OM) in feedstuffs, which were assessed separately by an in situ method and a direct in vivo measurement of the rumen degradation of OM in the diets of Holstein dairy cows. For this comparison, 80 individual data points were used from studies of dairy cows that were in midlactation and that had been cannulated in the rumen and abomasum. In vivo evaluation of the true degradability of OM in the rumen was based on rare earth digesta markers. Purine N served as a microbial marker. Feed samples were incubated in the rumens of dairy cows for 3, 6, 9, 12, 24, 48, and 72 h, and effective rumen degradation was calculated from the percentage of residual OM for rumen outflow rates of 4, 6, and 8%/h. Evaluations of rumen degradability of OM by the in situ method were correlated with actual in vivo measurements of rumen degradability of OM (r2 = 0.31, 0.34, and 0.37; SE of the estimate = 4.1, 4.0, and 3.9%, respectively). We concluded that the in situ method is a useful tool for providing reliable estimates of rumen degradability of OM in dairy cows.
Six multiparous Holstein cows were used in a 6 x 6 Latin square to investigate the ability of the Cornell Net Carbohydrate and Protein System to predict accurately rumen microbial yield, plasma urea N, and milk urea N. Estimations for microbial protein yield were compared with the measured excretion of purine derivative N in urine. A 3 x 2 factorial arrangement of treatments was adopted. Three concentrations of a rumen-undegradable protein (RUP) supplement (4.5, 14.9, and 29.1% of dry matter intake) and two levels of feed restriction (90 and 80% of ad libitum intake) were the corresponding factors. No effect of concentration of RUP supplement or feed restriction was detected on the excretion of purine derivative N in urine (mean, 18.5 g/d). Conversely, the Cornell system predicted a linear decrease in metabolizable protein from bacteria as the concentration of the RUP supplement increased. The Cornell system also predicted a significant reduction in metabolizable protein of microbial origin as feed restriction was increased. Measured values and values derived from the Cornell system for plasma and milk urea N increased linearly as the concentration of the RUP supplement increased. The Cornell system overpredicted milk urea N for cows consuming the highest RUP concentration. Predictions by the Cornell Net Carbohydrate and Protein System were of limited value because the empirical nature of the model is insufficiently rigorous to yield accurate predictions under the conditions described herein.
The objectives of this study were to evaluate effects of dietary factors that alter ruminal fermentability on rumen N degradation, microbial protein synthesis, duodenal flows, and digestibility of amino acids (AA) in the intestines and the total tract. The experiment was a double 4 x 4 quasi-Latin square with a 2(3) factorial arrangement of treatments. The dietary factors were extent of barley grain processing, coarse (processing index; PI = 75.5%) or flat (PI = 60.2%); forage-to-concentrate (F:C) ratio, low (35:65) or high (55:45) on a DM basis; and forage particle length (FPL), long (7.59 mm) or short (6.08 mm). Eight lactating cows with ruminal and duodenal cannulas were offered ad libitum access to a total mixed diet. There were no significant interactions between dietary treatments for ruminal N degradation or its duodenal flow and digestibility in the intestines. Passage of microbial protein to the duodenum was improved with increased F:C ratio of the diet but was not affected by grain processing or FPL. Ruminal digestibility of N was increased with increased F:C ratio (49 vs. 60%) and with reduced FPL (59 vs. 50%). Increased grain processing improved N digestibility both in the intestine (15%) and in the total tract (8%). Reduction in the FPL of the diets reduced intestinal N digestion by 14% without affecting the N digestion in the total tract. Increased extent of grain processing tended to enhance duodenal flows of AA. In contrast, reducing FPL lowered flows of dietary AA to the duodenum because of lowered flows of feed plus endogenous N. Increased F:C ratio of the diet did not change the flow of total AA, but there was a reduced flow of dietary AA and increased flow of microbial AA. Flows of several individual AA were increased by feeding flatly rolled barley with limited effects of F:C ratio or FPL. An interaction between grain processing and FPL was detected for flows of some AA. Diets formulated with flatly rolled barley plus long FPL increased Arg, Thr, Asp, Glu, Ser, Tyr, and nonessential AA (NEAA) by more than 24%, compared with other combinations of grain processing and FPL. Digestibility of essential AA (EAA) in the intestine (68%) was higher than that of NEAA (63%), but digestion of total AA (65%) was similar to that of total N (66%). Digestibilities of individual AA in the intestine ranged from 46 to 77% and were generally improved with increased grain processing. However, effects of F:C ratio or FPL on digestion of AA were limited. These results indicate that manipulation of dairy cow diets can improve ruminal N degradation, microbial protein synthesis, flows of AA to the duodenum, and intestinal digestibility of AA. Combining dietary factors can be more beneficial than changing individual dietary factors for improving the delivery of AA to the small intestine.
A data set constructed from research trials published between 1979 and 1998 was used to derive equations to adjust published tabular values for the rumen-undegradable protein (RUP) content of feeds to better predict the passage of nonammonia nonmicrobial N (NANMN) to the small intestine of lactating dairy cows. Both linear and nonlinear forms of equations were considered for making adjustments. Iterative processes were used to estimate equation parameters. A logistic equation was developed and considered to be the most optimal for adjustment of published tabular RUP contents of feeds. The equation is a function of dietary dry matter intake (DMI) and includes terms for tabular RUP and nonprotein N contents of individual feeds. The equation has a standard error of prediction of 69.29 g of NANMN/ d per cow and a root mean square prediction error of 104.63 g of NANMN/d per cow. Independent evaluation of the equation indicated that the concept of variable RUP content for feeds based on DMI is correct. Further refinements may be needed as other data become available to quantify the effects of additional factors on the RUP value of feeds.
In ruminant animals, endogenous N (EN) secretions contribute to meeting the N requirement of the ruminal microflora. The EN also constitutes a sizable portion of the duodenal N flow, which might be available to the host animal. Most measures of EN have been accomplished with highly invasive techniques or unusual semisynthetic diets. By utilizing a statistical approach and data obtained from studies reporting duodenal, ileal, and fecal N flows in cattle, the EN losses and true digestibility of N were estimated for different segments of the gastrointestinal tract of cattle. A simulation for a reference diet (24.2 g of N/kg of OM, 32% NDF and carbohydrates of medium fermentation rate) consumed at 2% of BW daily estimated that the minimal contribution of EN to the N available in the rumen was 39%. The free EN represented 13% of the duodenal N flow, and when bacterial N of EN origin was considered, EN contributed 35% of the total N flow. The minimal entry of EN into various segments of the gastrointestinal tract was also estimated as: foregut, 10.54; small intestine, 3.10; and hindgut, 5.0 g/kg of OMI. Rumen dietary N degradability was 0.68, and true N digestibilities in the small intestine and hindgut were 0.75 and 0.49, respectively. A better understanding of the factors involved in EN losses will allow for a more accurate estimation of both N supply and N requirements. This will translate into improved accuracy of diet formulation and less N excreted into the environment.
ABSTRACT Twenty-four,high,producing,Holstein cows,(14 primiparous,and 10 multiparous) were,fed,concentrate,mix,containing heat-treated,soybean,meal,without,or with,15 g of added,DL-methionine daily provided,as 50 g of ruminally,protected methionine,product,during,wk,4 through 16 postpartum.,The 15% crude,protein mixed,diets,contained,30% (dry mat- ter basis) corn silage, 15% alfalfa hay, and 55% concentrate,mix. Covariant adjusted yields of milk (34.6 and 33.1 kg/d), 4% fat-corrected,milk,(28.4 and,27.6 kg/d), and solids-corrected milk (29.0 and 28.5 kg/d) were,not,increased,by feed- ing supplemental,methionine.,Percentages of fat (2.81 and,2.92) and,protein,(2.88 and 2.92) were similar, whereas total solids (11.49 and,12.69) and solids-not-fat (8.68 and,8.77) were,higher with,supple- mental,methionine.,Dry,matter,in- takes,(20.2 and,21.0 kg/d) were,higher when,cows,were,fed supplemental,methi- onine. Ruminal pH, volatile fatty acids, and,ammonia,as well as blood,serum,urea and,glucose,were generally unaffected,by methionine,supplementation. Concentra- tions of methionine,in arterial and venous
Attempts have been made to increase nutrient availability for milk production by increasing feed intake, optimizing ruminal fermentation, and supplementing nutrients to the diet that will escape ruminal degradation. Energy and N are the nutritional factors that most often limit microbial growth and milk production. Ruminal fermentation and flow of microbial and dietary protein to the small intestine are affected by feed intake and by the amount and source of energy and protein in the diet. Feeding protein and carbohydrate that are not degraded in the rumen increases the quantity of dietary protein that passes to the small intestine but may decrease the quantity of microbial protein that is synthesized in the rumen. This often results in only small differences in the total NAN that passes to the small intestine. Because microbial protein supplies a large quantity of total AA that passes to the small intestine, differences in passage of individual AA often are only slight. Additional research with cows consuming large amounts of feed are needed to identify combinations of feed ingredients that synchronize availabilities of energy and N for optimizing ruminal digestion, microbial protein synthesis, nutrient flow to the small intestine, and milk production and composition.
Three lactating cows fitted with rumen cannulas and three cows fitted with proximal duodenal cannulas were used to determine the effect of in situ rumen degradation on the AA profile of rumen-undegraded protein of 12 feedstuffs. Intestinal digestibility of rumen-undegraded protein was determined using the mobile bag technique. The absorbable AA profile of rumen-undegraded protein for each feedstuff was compared with profiles of the original feedstuff and the rumen-exposed undegraded protein. Branched-chain AA in particular seemed to be rather resistant to degradation in the rumen, as was Phe. Lysine concentrations decreased in the undegraded protein fraction in 9 of 12 feedstuffs; the degradation of Met depended on the feedstuff. The absorbable AA profiles of undegraded protein, in general, closely reflected the AA profiles of the rumen-exposed residues, which suggests that rumen degradation had a greater influence than postruminal digestion on the postruminal provision of specific absorbable AA. Intestinal digestibility of undegraded protein varied from 37.8% for Eragrostis curvula hay to 98% for soybean meal; the constant digestibility factor used by most protein systems should be reconsidered.
Forty-one multiparous cows were utilized in a completely randomized design with a 2 x 2 factorial arrangement of treatments to evaluate the amount and degradability of dietary CP on production of milk and milk components. The TMR contained 25% alfalfa haylage, 25% corn silage, and 50% concentrate to provide either 16.4 or 19.4% CP with a calculated ruminal degradability of 55 or 70%. Intakes of DM, ADF, and NDF and BW were not different among treatments. Production of milk, 4% FCM, fat, CP, and SNF was not affected by amount or degradability of dietary CP. Milk CP percentage was not affected significantly by amount or degradability of CP. Milk fat percentage was increased by the diet that was high in ruminally undegradable protein (2.90 and 3.12; low and high ruminally undegradable protein, respectively). These data suggest that synthesis of milk and milk components was not limited by a shortage of AA or that the different dietary sources of supplemental CP did not alter AA availability.
Steam distillation methods of determining ammonium, nitrate, and nitrite in the presence of alkali-labile organic nitrogen compounds are described. They involve the use of magnesium oxide for distillation of ammonium, ball-milled Devarda alloy for reduction of nitrate and nitrite to ammonium, and sulfamic acid for destruction of nitrite. The methods are rapid, accurate, and precise, and they permit nitrogen isotope-ratio analysis of ammonium, nitrate, and nitrite in tracer studies using 15N-enriched compounds. They give quantitative recovery of ammonium, nitrate and nitrite added to soil and plant extracts, and appear suitable for analysis of biological materials.
Soybean meal, Atlantic menhaden fish meal, and corn gluten meal feeds varying in CP degradability and amino acid pattern were evaluated as supplements for high milk yield. Forty multiparous Holstein cows were fed a basal diet of corn silage:grain (blended, .8% urea, 12% CP, DM basis) ad libitum in wk 1 to 18 of lactation. During wk 1 to 3 of lactation, diet DM was 16% CP (basal plus soybean, fish, and corn gluten meals; each source contributed equal CP). On d 22, 10 cows were assigned to each of four diets: basal, 12% CP, DM basis or a diet containing 16% CP, DM basis with either soybean, fish, or corn gluten meal providing the supplemental CP. Cows readily ate all diets. Peak milk yields occurred later and were higher for cows fed soybean (wk 8, 38.9 kg/d) and fish meals (wk 9, 41.6 kg/d) compared with those fed the basal diet (wk 4, 31.0 kg/d) or corn gluten meal (wk 5, 37.5 kg/d). Milk protein yield was greater for cows fed soybean and fish meals. Fish meal decreased milk fat test (3.3 to 2.8%); however, due to differences in milk yields, fat yields were similar for cows fed soybean and fish meals. Productive N (milk + retained N) was greater and BW loss was less for cows fed soybean and fish meals. These data indicate the importance of CP degradability and amino acid pattern on performance.
The aim of this study was to compare two procedures used to estimate post-abomasal availability of feedstuff proteins in ruminants: (1) nitrogen disappearance from intestinal nylon bags; (2) true intestinal digestibility (dr). Dietary amino acid supplies and digestibilities were also evaluated. Three Italian Holstein rumen-and duodenum-fistulated cows were used. Animals were fed at an energy level equal to 1.7 times the maintenance requirement. Of the 29 proteic feedstuffs tested, 19 had intestinal digestibilities of over 90%: 17 of these were of vegetable origin and two were of animal origin. Nylon bag intestinal protein disappearances were over 90% for only 11 feedstuffs. Eighteen feedstuffs did not show any differences between the two procedures, while intestinal digestibility appeared superior to protein disappearance in ten raw materials (the opposite result was obtained in only one feedstuff). Amino acid intestinal digestibilities corresponded to source protein composition.
Ninety primiparous and 150 multiparous Israeli-Holstein dairy cows were allotted at random into three groups. One group (LSBM) was given 170 g crude protein (CP) per kg dry matter (DM). The two other groups were given 210 g CP per kg DM with the extra 40 g CP per kg DM supplied either by soya-bean meal (HSBM) or by fish meal (HFM). Roughage supplied proportionately 0·20 of the dietary DM and was maize silage with groundnut hay in the winter and wheat silage with oat grass in the summer. The primiparous and multiparous cows were offered the experimental diets for 16 and 24 weeks, respectively.
Milk, milk fat and milk protein production (kg/day), for treatments LSBM, HSBM and HFM, were: 39·3, 40·0, 40·8 ( P > 0·05); 1·12, 118, 1·06 ( P < 0·05) and 1·21, 1·23, 1·26 ( P > 0·05) for multiparous cows and 29·4, 31·2, 33·4 ( P < 0·05); 0·89, 1·07, 0·93 ( P < 0·01) and 0·92, 0·98, 1·05 ( P < 0·05) for primiparous cows, respectively. Cows of high yield potential responded more to increasing dietary protein level than did cows of low yield potential. Average live-weight gains on treatments LSBM, HSBM and HFM were (g/day): 220, 160 and 310 ( P < 0·05) in multiparous cows and 220, 170 and 230 ( P < 0·05) i n primiparous cows, respectively. Pregnancy rates, 16 weeks after parturition, were 0·65, 0·52 and 0·72 ( P < 0·05), in the LSBM, HSBM and HFM groups, respectively. The decrease in pregnancy rate in the HSBM cows, occurred in primiparous cows and cows in their fourth or later lactation but not in cows in their second or third lactation. The milk production of primiparous and multiparous cows in relation to the level and source of dietary CP and the utilization of energy and protein for milk production is discussed.
In situ evaluation of the duodenal amino acid (AA) profile was attempted in a 4 × 4 Latin square study using four lactating Holstein cows fitted with ruminal and duodenal cannulas. Dietary supplemental crude protein (CP) sources, making up 40% of the dietary CP, were: soybean meal, cottonseed meal, corn gluten meal or urea. Duodenal flow of organic matter (OM) and CP was determined in vivo by means of constant infusion of ytterbium and chromium, and predicted in situ from rumen degradation. Purines were used as microbial markers. In situ calculation of the AA profile, expressed as g AA in 100 g of total AAs, was based on the composition of AA in feed and in isolated bacteria as well as on in situ rumen degradation of OM and CP. The AA profile in the duodenum when assessed in vivo was affected by the nature of the supplemental protein; in situ assessment of the AA profile resulted in comparable profiles. The data are interpreted to suggest that the in situ method enables prediction of the profile of AA (g AA/100 g total AA) flowing to the duodenum, and that the undegraded portion of supplemented protein affects that profile.
At parturition, groups of six cows (two primiparous) were assigned randomly to experimental diets composed of wheat silage, concentrate containing 11.4% yellow grease, corn, and supplemental protein sources. Protein sources were soybean meal, heated soybean meal, and a combination of corn gluten and heated soybean meals. Intakes of DM, NDF, and NEL were not affected by undegraded protein levels (trial 1). Milk and 4% FCM yields and percentages of CP, lactose, SNF, and total solids were not influenced by protein source. Mobilization of body tissue was accelerated by heated soybean meal. During wk 1 to 4 postpartum, efficiency of NEL utilization was greater for cows receiving the combination treatment than for those receiving the soybean meal treatment. During wk 4 to 8, cows fed the heated soybean treatment utilized NEL more efficiently for milk yield than cows fed the combination treatment. Efficiency of utilization of absorbed protein was not affected by level of undegraded protein. At wk 9, fat was removed from the concentrate, and a second trial was conducted. Intakes of DM and NEL were reduced for cows fed the combination treatment. Milk yield and composition and efficiency of utilization of NEL and absorbed protein were not affected by level of undegraded protein.
In situ evaluation of the amount and composition of duodenal crude protein flow was examined in a 4 x 4 Latin square study using four lactating Holstein cows fitted with ruminal and duodenal cannulas. Dietary supplemental CP sources, making up 40% of the dietary CP, were: soybean meal, cottonseed meal, com gluten meal or urea. Duodenal flow of organic matter (OM) and CP was determined in vivo by means of constant infusion of Yb and Cr, and was predicted in situ from rumen degradation. Purines were used as microbial markers. The two methods of estimating ruminally undegraded protein ranked the diets similarly. Microbial CP (1.9 to 2.1 kg/d) was estimated to make up 57% to 68% of the duodenal CP flow in the experimental diets. Efficiency of microbial protein synthesis were 201 (SEM 16) g CP/kg OM truly digested in the rumen, and 224 (SEM 18) g CP/kg OM disappearing in the rumen. Data are interpreted to suggest that the in situ method enables a prediction of total protein flow to the duodenum which is comparable to that obtained using the in vivo method. The added practicality of the former method renders it advantageous.
The intestinal disappearance and simultaneous arterial inflow and portal appearance of individual amino acids (AA) were studied in sheep fed closed formula, unrefined high (H.P.) and medium (M.P.) protein diets. Gut contents were sampled through four intestinal cannulae and blood was sampled through portal and arterial catheters. The amount of total and amino N that was fed decreased on passage into the duodenum but increased in the jejunum, and then again decreased steadily towards the terminal ileum. The amounts of AA passing into the duodenum were significantly higher when the H.P. rather than the M.P. diet was fed. No dietary differences in AA were noted at the ileo-cecal junction, however, meaning that greater amounts of AA disappeared from the intestine when the H.P. diet was fed. The amounts of AA appearing in portal blood were 30 to 80% of those disappearing from the intestine and were greater in sheep fed the H.P. diet. The amount of AA passing into the duodenum also significantly affected the concentrations of AA in arterial blood. Less [U-14C]glutamic acid than [U-14C]alanine, that was infused into abomasum, was detected in the digesta passing through the pylorus. The same also was true for the unlabeled free form of glutamic acid. The portal appearance of both unlabeled and labeled glutamic acid was negligible, but that of alanine was considerable. Variable amounts of [14C]citrulline, [14C]arginine, and [14C]urea were detected in the blood following the abomasal infusions of labeled glutamic acid or alanine. The portal appearance of these labeled metabolites was always negative, however, implying that they were utilized, and not formed, by gut tissues.
Holstein cows in early lactation, producing about 30 kg/d of milk, were fed high energy diets containing 5% Megalac. Three protein treatments, soybean meal diet (16% CP), fish meal diet (16% CP), and soybean meal-fish meal diet (20% CP) were compared in a change-over design. Digestibilities of DM, gross energy, CP, and ADF were not affected significantly by protein treatments. The fish meal diet decreased DMI but increased milk and SCM production compared with the soybean meal diet. Daily production of milk, SCM, and milk components (fat, protein, and lactose) were highest and BW gain lowest for the high protein soybean meal-fish meal diet. The fish meal and soybean meal-fish meal diets increased fat percentage but decreased lactose percentage of milk compared with soybean meal diet. This suggests that, for each diet, the energy supply was adequate, and the observed changes were the effects of protein (i.e., AA) supply to the cows. Thus, there seems to be good reason to feed a good quality undegradable protein like fish meal to cows producing more than 30 kg/d of milk.
Establishing conditions under which rumen fermentation will be optimized requires an understanding of the nutrient requirements of the mixed microbial population. The major nutrients required by rumen microbes are carbohydrates and proteins, but the most suitable sources and quantities needed to support maximum growth have not been determined. Digestion of proteins results in the production of peptides, which can accumulate in the rumen. Peptides are further hydrolyzed to amino acids, some of which are deaminated, producing ammonia. Although peptides, amino acids, and ammonia all may individually serve as sources of N for various microbes, the total population achieves the highest growth rate on mixtures of all three sources. In a somewhat analogous manner, carbohydrates are digested by exoenzymes to oligosaccharides that are available for crossfeeding by the mixed microbial population. Based on data from both in vitro and in vivo studies, there is general agreement that rate of digestion of carbohydrates is the major factor controlling the energy available for microbial growth; in addition, rate of digestion of total carbohydrate is directly related to proportion of starches, pectins, and sugars. Proteins affect both total fermentation and production of microbial DM per unit of carbohydrate fermented. It appears that the quantity of ruminally available protein needed to optimize microbial growth may, under some conditions, be as high as 14 to 15% of diet DM.
A method for direct purine N isolation and determination was modified from the method of Zinn and Owens for rapid determination of purines. By this method, N derived from purines in digesta was measured and collected for 15N determinations. Measurements of purine N in 33 samples of ruminal contents and duodenal digesta of sheep and goats were compared with purine determinations in the same samples. The results showed that essentially all the N in the purines that could be isolated by the Zinn and Owens procedure also could be detected by N isolation and determination. Determinations of 15N in the NH3 N, NAN, and purine N fractions in a continuous culture in vitro showed significant differences in the 15N enrichment curves between diets based on either roasted or raw soybean meal.
Four Holstein cows fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square to investigate the effects of source (corn gluten meal or soybean meal) and amount (14.5 or 11.0%) of CP on ruminal fermentation, passage of nutrients to the small intestine, and animal performance. Cows wee fed for ad libitum intake a diet of 60% corn silage and 40% concentrate on a DM basis. The treatments, arranged in a 2 x 2 (source x amount of CP) factorial, were 1) 14.5% CP, soybean meal; 2) 11.0% CP, soybean meal; 3) 14.5% CP, corn gluten meal; and 4) 11.0% CP, corn gluten meal. Digestion in the rumen of OM, starch, ADF, and NDF was not affected by source or amount of CP in the diet. Total VFA and NH3 concentrations in ruminal fluid were increased by feeding diets that contained 14.5% CP or soybean meal. FLows of non-NH3 N and amino acids to the duodenum were greater in cows fed the 14.5% CP diets because of a greater flow of non-NH3 nonmicrobial N to the duodenum. Larger amounts of lysine passed to the duodenum when cows were fed soybean meal compared with corn gluten meal. Microbial N flow to the duodenum and efficiency of microbial growth were not affected by treatments, suggesting that ruminal NH3 concentration was not limiting for maximal microbial protein synthesis. Feeding 14.5% CP diets increased the production of milk (29.5 vs. 26.8 kg/d) and milk protein compared with 11.0% CP diets, possibly because of greater passage of amino acids to the small intestine. Feeding soybean meal to cows increased production of milk protein compared with feeding corn gluten meal, possibly because more lysine passed to the small intestine.
Ten holstein and 10 Ayrshire cows were fed diets containing undegradable intake protein from either fish meal or corn gluten meal. Cows were introduced to diets 10 d before projected calving date and individually fed blended rations until 60 d postpartum. Diets were balanced for NE1, CP, and degradable and undegradable protein. Source of undegradable protein did not affect total or FCM yields, DM intake, or milk protein percentage. Cows on fish meal diets tended to lose less BW than those on the corn gluten meal supplement (5.3 vs. 10.3% loss of initial BW). Fish meal supplementation resulted in decreased milk fat and SNF percentage (3.2 vs. 4.2% and 8.37 vs. 8.65%, respectively), but diet did not affect total milk fat, protein, or SNF yield. Plasma nonesterified fatty acids decreased and serum insulin increased with increasing weeks postpartum but were not affected by diet. In this study, no significant advantage was found to using fish meal as a source of undegradable intake protein and feed cost was higher when it was used.
The contribution of different feedstuffs to nitrogen reaching the duodenum was evaluated in situ. Dacron bags containing barley grain, corn grain, wheat silage, corn silage, alfalfa hay, rye grass, whole cottonseeds, or soybean meal were suspended in the rumens of three dairy cows fed roughage and concentrate diets. The effective degradability of the nitrogenous and organic matter of feedstuffs was calculated from their residues after incubation in the rumen for 3, 6, 9, 12, 24, 36, or 48 h. The duodenal nitrogen content at ruminal outflows of 2, 5, or 8%/h was calculated as the sum of undegradable dietary nitrogen and potential microbial nitrogen (assuming 32 g N/kg ruminally degradable organic matter). Comparison of the in situ estimates with previously reported in vivo measurements of duodenal nitrogen in cattle fed diets with similar ingredients to the tested feedstuffs yielded a linear relationship (r2 = .887). The dacron bag technique appears to hold promise for the prediction of nitrogen flow to the duodenum.
Eighty primiparous cows were assigned to either soybean meal, fish meal, or A and B treatments. Commercial supplement A was a blend of meat and bone, meat, poultry, blood, and feather meals. Commercial supplement B included the same ingredients as A but had a higher amount of blood meal and also a low concentration of fish meal. In vitro undegradabilities of protein were 32.0, 37.8, 38.8, and 42.4% for soybean meal, fish meal, A, and B rations, respectively. Milk yields and body weight changes were not significantly affected by treatments. Because of the lower milk fat content on fish meal diet, FCM yield was lower for cows fed fish meal than soybean meal or B supplements. Milk protein content was 3.19, 3.19, 3.03, and 3.09% on soybean meal, fish meal, A, and B diets, respectively. The calculated protein efficiency (100* output/input) on soybean meal, fish meal, A, and B diets were 47.8, 51.6, 45.9, and 48.7, respectively. The undegraded protein in the fish meal after an 18-h in vitro incubation with protease enzyme (Streptomyces griseus, type V) had a higher concentration of methionine and lysine than the undegraded protein of other supplements. Flavor of milk produced on the soybean and fish meal diets was evaluated. No flavor differences were detected.
Four lactating cows fitted with ruminal cannulae and T-type cannulae in the proximal duodenum and terminal ileum were utilized to measure protein degradation in the rumen and amino acid flow to and absorption from the small intestine. Soybean meal, blood meal, feather meal, and a 50-50 combination of blood meal and feather meal provided 50% of the protein in diets that contained 50% grain mix, 40% corn silage, and 10% alfalfa pellets on a DM basis. Ruminal degradation of dietary CP was 53, 43, 32, and 37% for diets containing soybean meal, blood meal, feather meal, and the combination of meals. Cows fed the latter two diets also had lower ruminal NH3 concentrations and efficiency of bacterial protein synthesis compared to those fed the soybean meal diet. Total tract N digestibility was lower for diets containing feather meal (63.4%) and a combination of meals (66.3%) than the soybean meal diet (78.5%). Total amino acid flow to the duodenum was 19.3 and 15.6% higher for cows fed the feather meal and combined meal diets, respectively, compared with the soybean meal diet. Total amino acid absorption from the small intestine was higher as well as absorption of individual amino acids for the combined meal diet compared with the soybean meal diet. Absorption of individual amino acids, expressed as a percentage entering the duodenum, was lowest for the feather meal diet. Results from this study show that feeding a combination of blood meal and feather meal instead of soybean meal can increase intestinal supply and absorption of amino acids in dairy cattle.
Several by-product feeds are relatively high in crude protein and exhibit relatively low ruminal degradability, which make them desirable proteinaceous feeds for dairy cows. Therefore, by-product feeds have been and will continue to be important feeds for dairy cows. Factors are discussed that affect ruminal degradability of protein in distillers grains, distillers grains with solubles, brewers grains, corn gluten feed, corn gluten meal, meat meal, meat and bone meal, blood meal, and fish meal, and the potential of these feeds to provide supplemental amino acids needed by lactating dairy cows. The importance of maximizing synthesis of microbial protein and digestion of organic matter in the rumen is emphasized in relation to total amino acid passage to the small intestine. For these feeds to be used most successfully, they must be available from a dependable source at an economical cost and should supply amino acids that complement other amino acids passing to the small intestine. Benefits that should be realized from the successful use of by-product feeds include increased milk production from feeding proteins that have greater ruminal escape potentials and a reduced cost per unit of milk produced because of decreased use of expensive supplemental protein.
Four lactating Holstein cows fitted with rumen cannulae and T-type cannulae in proximal duodenum and terminal ileum were used to measure protein degradation in the rumen and amino acid flow and absorption in the small intestine. Soybean meal, whole soybeans, and whole soybeans extruded at 132 and 149 degrees C provided 50% of the protein in diets that contained 51% grain, 36% corn silage, and 13% alfalfa hay (dry matter). Spot samples of digesta were collected from duodenum and ileum during 96 h, and lanthanum was an indigestible marker to estimate flow and digestibility of nutrients. With diaminopimelic acid as a microbial marker, apparent degradations of dietary crude protein in the rumen were 73, 80, 66, and 60% for diets containing soybean meal, whole soybeans, and whole soybeans extruded at 132 and 149 degrees C. Because of the extensive degradation of protein with the raw soybean diet, less total amino acids reached the duodenum, and because of decrease of availability, absorption from the small intestine (g/day) was lowest with this diet. Feeding diets containing extruded whole soybeans increased availability of total essential amino acids in the small intestine compared with diets containing soybean meal and whole soybeans. Absorption from the small intestine (g/day and percent entering) of individual amino acids was generally higher for extruded whole soybean diets.
In dairy cows two distinct and important aspects of the interrelationship between protein and energy-yielding nutrients can be identified. First, a change of protein input can influence performance by changing overall plane of nutrition. To a large extent this results from changes of digestibility and associated intake of ration ingredients. Within this context it appears that at high levels of feeding rumen microbial demand for nitrogen per unit fermentable organic matter is high; initial failure to meet this need for nitrogen probably accounts for many responses to protein supplementation in practice through stimulation of ruminal digestion. Second is that changing "protein" supply to tissues can alter the pattern and efficiency of absorbed nutrient use. In early lactation protein supplementation favors partition of available nutrients toward mammary secretion. There are effects on glucose and fatty acid metabolism, all interacting with the endocrine system within a metabolic framework that tends to conserve those nutrients (amino acids, glucose) that are in shortest supply relative to demand. Response to increased input of amino acids depends both on physiological state of the cow and balance of all nutrients absorbed from the gastrointestinal tract.
Four lactating cows, each fitted with a rumen cannula and duodenal and ileal t-cannulae, were used to measure flow and digestion of nitrogenous compounds in the digestive tract. Dietary dry matter contained 17% crude protein and 50:50 forage:concentrate. Treatments were: 1) corn silage-soybean meal; 2) corn silage-heated soybean meal; 3) ammonia-treated corn silage-soybean meal; and 4) ammonia-treated corn silage-heated soybean meal. Flow of organic matter to the duodenum was overestimated when lanthanum or chromium ethylene-diaminetetraacetate was used as an indigestible marker. This resulted in low estimates of ruminal digestion of organic matter and high estimates of nitrogen flow to the duodenum. However, calculations using lanthanum or lignin as markers yielded similar organic matter flow to ileum and feces. With acid-detergent lignin as a marker, estimates of dietary nitrogen degraded in the rumen were: corn silage-heated soybean meal, 55.0% ammonia-treated corn silage-heated soybean meal, 58.8%; ammonia-treated corn silage-soybean meal, 63.3%; and corn silage-soybean meal, 66.0%. Digestion in the small intestine of nonammonia nitrogen was equal for all treatments suggesting that availability of heated soybean meal in the intestine was not different, although ruminal degradability tended to be lower. Feeding diets containing nonprotein nitrogen did not decrease available nitrogen at the duodenum.
Four lactating Holstein cows fitted with a rumen cannula and T-type cannulae in the duodenum and ileum were used in an experiment with a 4 X 4 Latin square arrangement of treatments. Diets containing soybean meal (SBM), corn gluten meal (CGM), wet brewers grains (WBG) and distillers dried grains with solubles (DDG) were compared with regard to protein degradability in the rumen and amino acid flow and absorption in the small intestine. The test protein sources provided about 50% of the dietary protein. Spot samples of digesta were collected during a 96-h period and lanthanum (La) was used as an indigestible marker to estimate flow and digestibility of nutrients. Apparent organic matter digestibility in the rumen was 31 +/- 4.8%, while true digestibility based on measurements of microbial organic matter averaged 55 +/- 5.1%. Ruminal ammonia-nitrogen (NH3-N) concentrations (mg/100 ml) were 10.1, 5.6, 6.9 and 6.4 for the SBM, CGM, WBG and DDG diets, respectively. Using diaminopimelic acid as a microbial marker, protein degradation in the rumen was higher for the SBM diet (70%) than for the CGM (45%), WBG (52%) and DDG (46%) diets. Flow of amino acids to the small intestine was generally higher than amino acid intake for all diets. Apparent absorption of amino acids from the small intestine was 70, 77, 71 and 66% of the amino acids entering the duodenum for the SBM, CGM, WBG and DDG diets, respectively. Actual amounts absorbed (g/d) were lowest for the SBM diet. It was concluded that diets containing CGM, WBG or DDG will generally supply more total amino acids to the intestine than a diet containing SBM. Net amounts of amino acids available for absorption in the intestine were also higher for these diets because protein availability in the intestine was not impaired even though protein was more resistant to microbial breakdown in the reticulorumen.
Soybeans were subjected to 12 heat treatments, differing in temperature and steeping (conditioning) time: control (no heat); 110 degrees C, 0 min; 110 degrees C, 30 min; 123 degrees C, 0 min; 123 degrees C, 30 min; 135 degrees C, 0 min; 135 degrees C, 30 min; 146 degrees C, 0 min; 146 degrees C, 15 min; 146 degrees C, 30 min; 153 degrees C, 30 min; and 160 degrees C, 30 min. These soybean treatments were tested for protein dispersibility index, absorbance at 420 nm, ADIN, pepsin-insoluble N, and in situ and in vitro protein degradation. Seven of these treatments (control; 123 degrees C, 30 min; 135 degrees C, 0 min; 135 degrees C, 30 min; 146 degrees C, 0 min; 146 degrees C, 30 min; and 153 degrees C, 30 min) were used in a feeding study involving 21 Holstein heifers (7 x 7 Latin square design replicated three times) and a lactation experiment (7 x 7 Latin square design replicated two times) using 14 multiparous Holstein cows in early lactation. Concentrations of branched-chain AA in blood plasma were used as indicators of protein uptake from the intestine in the heifer study, and production of 3.5% FCM was used to evaluate soybean treatments in the lactation study. Based on the criteria used, soybeans heated to 146 degrees C for 30 min were considered to be optimal. The protein dispersibility index and absorbance at 420 nm proved useful in evaluation of heat exposure of soybeans, and these procedures are suggested for routine monitoring of quality of commercially heated soybeans.
Thirty-six cows were in a 2 x 3 factorial study during the first 2 mo of lactation to examine effects on milk yield and composition of added fat (5% of feed DM) and percentage of ruminally undegradable protein (100, 120, or 140% of recommended intake) in the diet. The main source of added undegradable protein was a 1:1 (wt/wt) mixture of blood meal:hydrolyzed feather meal. Diets were low in ADF (ca. 14%) and were highly fermentable in the rumen. The amount of intermediate dietary protein reduced feed intake. Milk yield was high (40 to 44 kg/d), similar among treatment groups, and was sustained for the entire 60-d trail. All cows yielded milk of low fat content (2.1 to 3.2%); supplemental fat decreased proportions of C6 to C14, C18:2, and C18:3 in milk fat and increased C4, C16:0, C18:0, and C18:1. Higher dietary protein had a positive linear effect on milk fat percentage and increased C16:0 and decreased trans-C18:1 and C18:2 contents of milk fat. Added fat did not change total milk N but increased NPN as a percentage of total milk N. Percentage of total N in milk and yield of whey N was reduced when the intermediate protein diet was fed, associated with the lower DMI of this diet. A requirement for ruminally undegradable protein intake higher than recommended by NRC was not demonstrated with the highly fermentable diets fed in this study; however, ruminal acetate: propionate ratio and milk fat percentage were low.
Four Holstein cows were used in a 4 x 4 Latin square design to investigate the effects of soybean hulls and lignosulfonate-treated soybean meal on ruminal fermentation and nutrient passage to the duodenum. Diets contained 32% corn silage, 19.8% alfalfa-grass hay, and 48.2% concentrate (DM basis). Treatments, arranged in a 2 x 2 factorial, were concentrate mixes based on 1) corn and soybean meal, 2) corn and treated soybean meal, 3) soybean hulls and soybean meal, and 4) soybean hulls and treated soybean meal. Individual protein supplements supplied 40% of dietary CP, and corn or soybean hulls constituted 28% of dietary DM. Intake of OM (mean 18.9 kg/d) was similar among treatments, but intake of NDF was 42% greater, and intake of nonstructural carbohydrate was 55% less, for cows fed soybean hulls. Passage of OM to the duodenum was similar among diets, but flow of NDF was 43% greater, and flow of nonstructural carbohydrate was 56% less, for cows fed soybean hulls. Ruminal pH was similar, but total concentrations of VFA increased 7% when soybean hulls replaced corn. Ruminal digestion of dietary CP was 15% less for cows fed treated soybean meal, but bacterial N flows were similar among treatments. Soybean hulls were digested to a similar extent as corn, but few interactions occurred between supplemental carbohydrate and protein sources.
A new simple and rapid method for quantitative semimicro determination of blood urea is presented. Diacetyl monoxime and thiosemicarbazide form in acid medium with urea a red color complex with a maximum adsorption at 530 mµ stable at room temperature and requiring 0.2 ml. of 1:10 blood filtrate.
The use of markers to partition digestion within the gastrointestinal tract of ruminants
- Faichneg