Department of Animal Science, Cornell University, Ithaca, NY 14850.
Department of Animal Sciences, University of Florida, Gainesville 32611.
J Dairy Sci. 2019 Apr;102(4):3023-3035. doi: 10.3168/jds.2018-15447. Epub 2019 Feb 22.
The objective of this study was to evaluate the effects of a fermentation byproduct on rumen fermentation and microbial yield in high producing lactating dairy cattle. Eight ruminally cannulated multiparous Holstein cows averaging (mean ± standard deviation) 60 ± 10 d in milk and 637 ± 38 kg of body weight were assigned to 1 of 2 treatment sequences in a switchback design. Treatment diets contained (dry matter basis) 44% corn silage, 13% alfalfa silage, 12% ground corn, and 31% premix containing either a control mix of urea and wheat middlings (CON) or a commercial fermentation byproduct meal (Fermenten, Arm and Hammer Animal Nutrition, Princeton, NJ) at 3% diet inclusion rate (EXP). Diets were formulated to be isonitrogenous and isocaloric, with similar levels of neutral detergent fiber and starch. The trial consisted of three 28-d experimental periods, where each period consisted of 21 d of diet adaptation and 7 d of data and sample collection. Omasal nutrient flows were determined using a triple-marker technique and double-labeled NN-urea. The EXP diet provided 18 g/d more nonammonia N versus the CON diet, representing 3.0% of total N intake. Energy-corrected milk yield (41.7 and 43.1 kg/d for CON and EXP, respectively), milk fat, and protein yield and content did not differ between treatments. Total dry matter intake was similar between treatments (25.5 and 26.4 kg/d for CON and EXP, respectively). Ammonia N concentration and pool size in the rumen was greater in cows fed the EXP diet. No differences were observed in rumen or total-tract dry matter, organic matter, or neutral detergent fiber digestibility. Ruminal degradation of feed N was 15% lower in cows fed EXP diets, resulting in differences in omasal N flows. Results demonstrated the fermentation byproduct meal had a sparing effect on degradable feed protein, but did not increase microbial N flow from the rumen.
本研究旨在评估发酵副产物对高产泌乳奶牛瘤胃发酵和微生物产量的影响。8 头瘤胃可插管的经产荷斯坦奶牛，泌乳天数（平均±标准差）为 60±10d，体重为 637±38kg，采用反转设计分配到 2 种处理序列中的 1 种。处理日粮以（干物质基础）含有 44%的玉米青贮、13%的苜蓿青贮、12%的粉碎玉米和 31%的预混料，预混料中含有对照混合的尿素和小麦麸皮（CON）或商业发酵副产物饲料（ Fermenten，Arm and Hammer Animal Nutrition，Princeton，NJ），添加水平为 3%日粮（EXP）。日粮的配制是为了使氮平衡和能量平衡，中性洗涤纤维和淀粉的水平相似。试验由 3 个 28d 的实验期组成，每个实验期包括 21d 的日粮适应期和 7d 的数据和样品采集期。采用三重标记技术和双标记 NN-尿素测定瘤胃养分流量。与对照日粮相比，EXP 日粮提供了 18g/d 更多的非氨氮，占总氮摄入量的 3.0%。校正乳产量（对照和 EXP 分别为 41.7 和 43.1kg/d）、乳脂率和蛋白质产量和含量在处理间没有差异。处理间总干物质采食量相似（对照和 EXP 分别为 25.5 和 26.4kg/d）。与对照日粮相比，饲喂 EXP 日粮的奶牛瘤胃中氨氮浓度和氨氮库更大。瘤胃和全肠道干物质、有机物或中性洗涤纤维消化率没有差异。饲喂 EXP 日粮的奶牛瘤胃饲料氮降解率降低了 15%，导致瘤胃氮流量差异。结果表明，发酵副产物饲料对可降解饲料蛋白有节约作用，但不会增加瘤胃微生物氮流量。
