摘要
The objectives of this experiment were to evaluate the effect of feeding a culture of Saccharomyces cerevisiae on rumen metabolism and digestibility when cows are fed diets varying in starch content. Four lactating Holstein cows were assigned to a 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Treatments were low starch (LS; 23% of diet DM) and no yeast culture (YC; LS-control), LS and 15 g of YC/d (LS-YC), high starch (HS; 29% of diet DM) and no YC (HS-control), and HS and 15 g of YC/d (HS-YC). Periods lasted 28 d, with the last 9 d for data collection. Days 20 to 24 were used to determine production, nutrient flow, and digestibility. On d 25, 3 kg of corn grain DM was placed in the rumen 1 h before the morning feeding, and yields of milk and milk components were measured after the challenge. Blood was sampled −1, 3, 7, and 11 h relative to the morning feeding on d 24 and 25. Rumen pH was measured continuously on d 24 and 25. Rumen papillae were collected on d 24 and 28 to quantify mRNA expression of select genes. Supplementing YC increased yields of milk (26.3 vs. 29.6 kg/d), energy-corrected milk (ECM; 26.5 vs. 30.3 kg/d), fat (0.94 vs. 1.08 kg/d), true protein (0.84 vs. 0.96 kg/d), and ECM/dry matter intake (1.15 vs. 1.30) compared with the control but did not affect dry matter intake (22.6 vs. 22.9 kg/d). Cows fed HS had increased milk true protein percentage (3.18 vs. 3.31%) and yield (0.87 vs. 0.94 kg/d) compared with cows fed LS. Feeding HS-YC increased the proportion of dietary N incorporated into milk true protein from 24.9% in the other 3 treatments to 29.6%. Feeding HS increased the concentration of propionate (21.7 vs. 32.3 mM) and reduced that of NH3-N (8.3 vs. 6.7 mg/dL) in rumen fluid compared with the control, and combining HS with YC in HS-YC tended to increase microbial N synthesis compared with LS-YC (275 vs. 322 g/d). Supplementing YC to cows fed HS reduced plasma haptoglobin and rumen lactate concentrations, increased mean rumen pH, reduced the time with pH FFAR2 and FFAR3) and transporter (SLC16A3) of short-chain fatty acids but did not affect genes involved in transport of Na+/H+ or water or in inflammatory response. Supplementing YC to dairy cows improved lactation performance in diets containing low or high starch, and mechanisms might be partially attributed to improvements in rumen pH, digestion of fiber, microbial N synthesis, and reduction in acute phase response.
摘要译文
本实验的目的是评估饲喂酿酒酵母培养物对瘤胃代谢和消化率的影响，当奶牛饲喂不同淀粉含量的日粮时。四头泌乳荷斯坦奶牛被分配到一个4×4拉丁方设计和2×2因子排列的处理。处理是低淀粉（LS; 23％饮食DM）和无酵母培养物（YC;（LS-对照），LS和15g YC / d（LS-YC），高淀粉（HS; 29％饮食DM）和无YC（HS-对照），HS和15g YC / d（HS -YC）。期间持续28天，最后9天用于数据收集。第20-24天用于确定产量，营养流量和消化率。在第25天，在早晨喂食前1小时将3kg玉米粒DM放入瘤胃中，并在挑战后测量牛奶和牛奶成分的产量。在第24天和第25天，相对于早晨进食的血液取样-1,3,7和11小时。在第24天和第24天连续测量瘤胃pH。在第24天和第28天收集瘤胃乳头以量化选择基因的mRNA表达。补充YC增加牛奶产量（26.3对29。（ECM; 26.5 vs. 30.3 kg / d），脂肪（0.94 vs. 1.08 kg / d），真蛋白质（0.84 vs. 0.96 kg / d）和ECM /干物质（1.15对1。30）与对照相比，但不影响干物质摄入量（22.6对22.9 kg / d）。饲喂HS的奶牛增加了牛奶的真实蛋白质百分比（3.18比3.31％）和产量（0.87比0。94公斤/天）与LS喂养的母牛相比。饲喂HS-YC将掺入牛奶真蛋白中的膳食N的比例从其他3种处理中的24.9％提高至29.6％。与对照组相比，饲喂HS增加了丙酸盐的浓度（21.7 vs. 32.3 mM），降低了瘤胃液中NH 3 -N的浓度（8.3 vs. 6.7 mg / dL）HS-YC中HS与YC的结合倾向于与LS-YC（275与322g / d）相比增加微生物N合成。补充YC饲喂HS的奶牛降低血浆触珠蛋白和乳酸乳酸浓度，增加平均瘤胃pH值，用pH FFAR2和FFAR3）和短链脂肪酸的转运蛋白（SLC16A3），但不影响参与Na + + / + +或水的运输的基因或在炎症反应中。补充奶牛YC可以提高含有低淀粉或高淀粉日粮的泌乳性能，其机制可能部分归因于瘤胃pH值的改善，纤维的消化，微生物N合成，以及急性期反应的减少。
A.L.G.Dias[*][†];J.A.Freitas[*][1];B.Micai[*];R.A.Azevedo[*];L.F.Greco[*];J.E.P.Santos[*][‡];. Effect of supplemental yeast culture and dietary starch content on rumen fermentation and digestion in dairy cows[J]. Journal of Dairy Science, 2018,101(1): 201-221