Zhang Jun, Xu Xiaofeng, Cao Zhijun, Wang Yajing, Yang Hongjian, Azarfar Arash, Li Shengli
State Key Laboratory of Animal Nutrition, Beijing Engineering Technology Research Center of Raw Milk Quality and Safety Control, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
College of Agriculture, Ningxia University, Yinchuan 750021, China.
Animals (Basel). 2019 Jul 31;9(8):507. doi: 10.3390/ani9080507.
This study investigated the effect of tannin sources on nutrient intake, digestibility, performance, nitrogen utilization, and blood parameters in lactating dairy cows. Four multiparous lactating Holstein cows were used in a balanced 4 × 4 Latin square design, with each period lasting 28 days. Cows were randomly assigned to one of four dietary treatments: Control diet (CON, a totally mixed ration without tannin supplements), control diet supplemented with 3% bayberry condensed tannins (BCT), control diet supplemented with 3% condensed tannins (ACT), and control diet supplemented with 3% valonia hydrolyzed tannins (VHT). Dietary treatments did not significantly affect nutrient intake, milk yield or composition, microbial protein synthesis, nitrogen utilization efficiency, or plasma concentrations of glucose, non-esterified fatty acids, -hydroxybutyrate, total protein, and globulin, or the albumin-to-globulin ratio. Tannin supplements decreased the apparent total tract nutrient digestibility to varying degrees and significantly decreased the milk and blood urea nitrogen contents ( < 0.05). Tannin supplements altered nitrogen excretion routes in lactating dairy cows, and BCT significantly decreased the urinary nitrogen excretion ( = 0.04). Compared with the CON, ACT, and VHT diets, BCT yielded the highest nitrogen retention and nitrogen retention-to-digestible nitrogen ratio despite having a similar nitrogen utilization efficiency ( < 0.05). Bayberry condensed tannin supplementation may be a potential way to improve nitrogen utilization and reduce concerns regarding nitrogen excretion in dairy cows.
本研究调查了单宁来源对泌乳奶牛营养物质摄入量、消化率、生产性能、氮利用率和血液参数的影响。选用四头经产泌乳荷斯坦奶牛，采用平衡的4×4拉丁方设计，每个试验期持续28天。奶牛被随机分配到四种日粮处理之一：对照日粮（CON，一种不添加单宁的全混合日粮）、添加3%杨梅缩合单宁（BCT）的对照日粮、添加3%缩合单宁（ACT）的对照日粮和添加3%橡椀水解单宁（VHT）的对照日粮。日粮处理对营养物质摄入量、产奶量或组成、微生物蛋白合成、氮利用效率或血浆葡萄糖、非酯化脂肪酸、β-羟基丁酸、总蛋白和球蛋白浓度，或白蛋白与球蛋白比值均无显著影响。单宁添加物不同程度地降低了表观全肠道营养物质消化率，并显著降低了牛奶和血液尿素氮含量（P<0.05）。单宁添加物改变了泌乳奶牛的氮排泄途径，BCT显著降低了尿氮排泄量（P = 0.04）。与CON、ACT和VHT日粮相比，尽管氮利用效率相似，但BCT的氮保留量和氮保留量与可消化氮比值最高（P<0.05）。添加杨梅缩合单宁可能是提高奶牛氮利用率和减少对氮排泄担忧的一种潜在方法。
