5 research outputs found
Effects of alfalfa silage storage structure and roasting corn on ruminal digestion and microbial CP synthesis in lactating dairy cows
No full textThe objective of this experiment was to quantify the effects of unroasted or roasted ground-shelled corn (GSC), when fed with
alfalfa ensiled in bag, bunker, or O2
-limiting tower silos on ruminal digestion and microbial CP synthesis in lactating dairy cows.
The roasted corn was heat-treated in a propane-fired roasting system. Alfalfa was harvested as second cutting from fields with
regrowth of the same maturity. A portion of each field was allotted to each silo. The diets with 3 3 2 factorial arrangement of
treatments were fed to six multiparous rumen-cannulated Holstein cows in a cyclic change-over design with five 21-day periods.
Experimental diets were comparable and averaged (on dry matter (DM) basis): 410 g/kg alfalfa silage (AS), 150 g/kg corn silage,
350 g/kg GSC, 50 g/kg soybean meal, 40 g/kg roasted soybeans, 177 g/kg CP, 264 g/kg NDF and 250 g/kg starch. Nutrient flow was
quantified by the omasal sampling technique with use of three markers (Co, Yb and indigestible NDF). Continuous infusion of 10%
atom excess (
15
NH4
)2
SO4 was used to label microbial CP. None of the interactions between storage structure of dietary AS and
corn type were significant. DM intake was not different among dietary treatments, averaging 24.5 kg/day across diets. Means of
ADF digested in the rumen for cows fed diets with AS from bag, bunker and O2
-limiting tower silo were 2.1, 1.7 and 2.1 kg/day,
respectively, and was lower in cows fed AS from the bunker silo. This response may partly be a reflection of the higher intake
of ADF by cows fed AS ensiled in the O2
-limiting tower silo compared with the bunker. There was a slightly greater supply of
fermentable substrates for cows fed diets with roasted compared with unroasted GSC. The small increases in yield of milk protein
and lactose observed in the previous production trial in cows fed diets containing roasted corn may have occurred because of
greater supply of fermentable substrate
Effect of alfalfa silage storage structure and roasting corn on production and ruminal metabolism of lactating dairy cows
No full textThe objective of this study was to determine if feeding roasted corn would improve production and nutrient utilization when supplemented to lactating cows fed 1 of 3 different alfalfa silages (AS). Forty-two lactating Holstein cows (6 fitted with ruminal cannulas) averaging 77 d in milk and 43 kg of milk/d pretrial were assigned to 2 cyclic changeover designs. Treatments were AS ensiled in bag, bunker, or O 2-limiting tower silos and supplemented with ground shelled corn (GSC) or roasted GSC (RGSC). Silages were prepared from second-cutting alfalfa, field-wilted an average of 24 h, and ensiled over 2 d. Production and N utilization were evaluated in 36 cows during four 28-d periods, and ruminal fermentation was evaluated with 6 cows during five 21-d periods. Experimental diets contained 40% AS, 15% corn silage, and 35% of either GSC or RGSC on a dry matter basis. No significant interactions between AS and corn sources were detected for any production trait. Although the chemical composition of the 3 AS was similar, feeding AS from the O 2-limited tower silo elicited positive production responses. Yields of 3.5% fat-corrected milk and fat were increased 1.7 kg/d and 150 g/d, and milk fat content was increased 0.3% when cows were fed diets based on AS from the O 2-limiting silo compared with the other 2 silages. The responses in milk fat were paralleled by an average increase in acid detergent fiber digestibility of 270 g/d for cows fed AS from the O 2-limiting tower silo. However, ruminal concentrations of lipogenic volatile fatty acids were unchanged with AS source. Cows fed RGSC consumed 0.6 kg/d more dry matter and yielded 30 g/d more protein and 50 g/d more lactose than cows fed GSC diets. There was no evidence of increased total tract digestibility of organic matter or starch, or reduced ruminal NH 3 concentration, when feeding RGSC. Free amino acids increased, and isovalerate decreased in rumen fluid from cows fed RGSC diets. However, responses in production with roasted corn were mainly due to increased dry matter intake, which increased the supply of energy and nutrients available for synthesis of milk and milk components
Estimation of ruminal degradation and intestinal digestion of tropical protein resources using the nylon bag technique and the three-step in vitro procedure in dairy cattle on rice straw diets
No full textThe experiment was carried out using fistulated multiparous Holstein Friesian crossbred (75% Holstein Friesian and 25% Red Sindhi) dairy cows in their dry period fed on untreated rice straw to evaluate the nutritive value of local protein feed resources using the in sacco method and in vitro pepsin-pancreatin digestion. Experimental feeds were cottonseed meal (CSM); soybean meal (SBM); dried brewery\u27s grains (DBG); palm kernel meal (PSM); cassava hay (CH); leucaena leaf meal (LLM). Each feedstuff was weighed into duplicate nylon bags and incubated in each of the two rumen fistulated cows for 0, 2, 4, 8, 16, 24, and 48 h. Rumen feed residues from bags of 16 h incubation were used for estimation of lower gut digestibility by the technique of in vitro pepsin-pancreatin digestion. Ruminal ammonia-nitrogen (NH3-N) concentrations did not differ between treatments or time with a mean of 5.5 mg%. Effective degradability of DM of CSM, SBM, DBG, PSM, CH and LLM were 41.9, 56.1, 30.8, 47.0, 41.1 and 47.5%, respectively. Effective degradabilities of the CP in feedstuffs were 49.6, 59.2, 40.9, 33.5, 47.3 and 65.0% for the respective feedstuffs. The CP in vitro pepsin-pancreatin digestibility as ranked from the highest to the lowest were SBM, CSM, LLM, CH, DBG, PSM, respectively. The intestinal and total tract digestion of feedstuffs in the current study were relatively lower than that obtained from previous literature. The results of this study indicate that SBM and LLM were highly degradable in the rumen, while CH, CSM and DBG were less degradable and, hence resulted in higher rumen undegradable protein. Soybean meal and LLM could be used to improve rumen ecology whilst CH, CSM and DBG could be used as rumen by-pass protein for ruminant feeding in the tropics
Supplementation of cassava hay as a protein replacement for soybean meal in concentrate supplement for dairy cows
No full textCrossbred Holstein-Friesian dairy cows (3) in mid-late lactation were randomly allocated to 3 ratio of cassava hay (CH) and soybean meal (SBM) (CH:SBM) in concentrate supplement treatments (0:100, 60:40, 100:0) according to a 3
73 latin square design. Concentrate mixture containing 16% CP was given to animals at 2 equal parts (2% of body weight/day) while urea-treated rice straw (5% urea) (UTRS) was given on ad lib. The experiment revealed that increasing CH: SBM ratio in concentrate had no effect on dry matter intake and digestibility while reduced concentrations of ruminai ammonia nitrogen (NH 3-N) and blood urea nitrogen (BUN) were reduced. Milk yield across treatments were similar (8.0-8.5 kg/hd/d) while fat contents of milk tended to linearly increase as ratio of CH to SBM in concentrate increased. Moreover, increasing levels of CH to SBM ratio in concentrate linearly increased income over feed, thus resulted in more milk income return. Conclusions can be made that CH should be recommended to be used as a protein source replacement for soybean meal in concentrate for a sustainable dairy production in the tropics
Evaluation of models to predict the stoichiometry of volatile fatty acid profiles in rumen fluid of lactating Holstein cows
No full textVolatile fatty acids (VFA), produced in the rumen by microbial fermentation, are the main energy source for ruminants. The VFA profile, particularly the nonglucogenic (acetate, Ac; butyrate, Bu) to glucogenic (propionate, Pr) VFA ratio (NGR), is associated with effects on methane production, milk composition, and energy balance. The aim of this study was to evaluate extant rumen VFA stoichiometry models for their ability to predict in vivo VFA molar proportions. The models were evaluated using an independent data set consisting of 101 treatments from 24 peer-reviewed publications with lactating Holstein cows. All publications contained a full diet description, rumen pH, and rumen VFA molar proportions. Stoichiometric models were evaluated based on root mean squared prediction error (RMSPE) and concordance correlation coefficient (CCC) analysis. Of all models evaluated, the 1998 Friggens model had the lowest RMSPE for Ac and Bu (7.2 and 20.2% of observed mean, respectively). The 2006 Bannink model had the lowest RMSPE and highest CCC for Pr (14.4% and 0.70, respectively). The 2008 Bannink model had comparable predictive performance for Pr to that of the 2006 Bannink model but a larger error due to overall bias (26.2% of MSPE). The 1982 Murphy model provided the poorest prediction of Bu, with the highest RMSPE and lowest CCC (24.6% and 0.15, respectively). The 1988 Argyle and Baldwin model had the highest CCC for Ac with an intermediate RMSPE (0.47 and 8.0%, respectively). The 2006 Sveinbjörnsson model had the highest RMSPE (13.9 and 34.0%, respectively) and lowest CCC (0.31 and 0.40, respectively) for Ac and Pr. The NGR predictions had the lowest RMSPE and highest CCC in the 2 models of Bannink, whereas the lowest predictive performance was in the 2006 Sveinbjörnsson model. It appears that the type of VFA produced is not a simple linear relationship between substrate inputs and pH as currently represented. The analysis demonstrates that most rumen VFA stoichiometric approaches explain a large part of the variation in VFA molar proportions among diets, in particular for Ac, whereas predictive power for Pr and Bu differ largely among approaches. The move toward feed evaluation systems based on animal response might necessitate an improved representation of rumen fermentation, focused on improving our understanding of VFA proportions in diets that vary from the mean
