Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, UT.
Department of Plants, Soils, and Climate, Utah State University, Logan, UT.
J Anim Sci. 2018 Sep 7;96(9):3993-4001. doi: 10.1093/jas/sky259.
Legumes that contain condensed tannins may have lower ruminal protein degradation than alfalfa. The present study investigated the effects of feeding birdsfoot trefoil (Lotus corniculatus L.) hay on lactational performance and N utilization and excretion. Eight multiparous Holstein cows in midlactation (150 ± 22.3 d-in-milk) were randomly assigned to 2 treatments [alfalfa hay-based total mixed ration (AHT) or birdsfoot trefoil hay-based total mixed ration (BHT)] in a crossover design with 2 experimental periods. Each experimental period lasted 17 d (14 d of adaptation and 3 d of sampling and total collection). Hays comprised approximately 50% of DM in experimental diets. There were no treatment effects on dry matter intake (DMI; 21.4 vs. 20.7 kg/d), milk yield (29.4 vs. 28.1 kg/d), milk fat concentration (3.20% vs. 3.21%), and milk protein concentration (3.20% vs. 3.16%) for AHT and BHT, respectively. In addition, dietary treatments did not affect milk yield/DMI or energy-corrected milk yield/DMI. In contrast, apparent crude protein digestion decreased in cows fed BHT compared with those fed AHT (60.7% vs. 69.1%). Concentration of milk urea-N decreased by feeding BHT compared with AHT (11.9 vs. 13.3 mg/100 mL), whereas total N excretion did not differ between AHT and BHT diets. However, cows fed BHT excreted more N in feces (194 vs. 168 g/d), whereas urinary N excretion was lower compared with cows fed AHT. The shift of N to feces resulted in a decrease in urinary N:fecal N ratio in cows fed BHT relative to those fed AHT. Overall results in the current study suggest that feeding birdsfoot trefoil in dairy diets shifts routes of N from urine to feces compared with feeding alfalfa hay, with little effect on lactational performance. Reduction in urinary N and any impact on environment may be attributed to functional effect of condensed tannins in birdsfoot trefoil hay.
与苜蓿干草相比，含有缩合单宁的豆类可能会降低瘤胃蛋白质的降解率。本研究调查了给鸟类三叶草（Lotus corniculatus L.）干草对泌乳性能和氮利用与排泄的影响。8 头处于泌乳中期（泌乳 150 ± 22.3 天）的荷斯坦奶牛随机分配到 2 种处理组[苜蓿干草基础全混合日粮（AHT）或鸟类三叶草干草基础全混合日粮（BHT）]，采用交叉设计进行 2 个实验期。每个实验期持续 17 天（14 天适应期和 3 天采样和总收集期）。干草约占实验日粮干物质的 50%。AHT 和 BHT 对干物质采食量（DMI；21.4 与 20.7kg/d）、产奶量（29.4 与 28.1kg/d）、乳脂浓度（3.20%与 3.21%）和乳蛋白浓度（3.20%与 3.16%）均无影响。此外，日粮处理不影响产奶量/DMI 或能量校正奶产量/DMI。相比之下，与 AHT 相比，饲喂 BHT 的奶牛的粗蛋白表观消化率降低（60.7%与 69.1%）。与 AHT 相比，饲喂 BHT 时奶牛的乳尿素氮浓度降低（11.9 与 13.3mg/100mL），但 AHT 和 BHT 日粮的总氮排泄量没有差异。然而，与 AHT 相比，饲喂 BHT 的奶牛粪便中的氮排泄量更多（194 与 168g/d），而尿液中的氮排泄量则更低。与 AHT 相比，饲喂 BHT 的奶牛粪便中的氮排泄量增加，尿液中的氮排泄量减少，导致粪便中的氮与尿液中的氮的比值降低。本研究的总体结果表明，与饲喂苜蓿干草相比，在奶牛日粮中添加鸟类三叶草会将氮的排泄途径从尿液转移到粪便，而对泌乳性能几乎没有影响。尿液氮的减少和对环境的任何影响可能归因于鸟类三叶草干草中缩合单宁的功能作用。
