瘤胃灌注氯化铵诱导的低日粮阴阳离子差对泌乳奶牛生产性能、血清及尿液代谢产物的影响。
Effects of low dietary cation-anion difference induced by ruminal ammonium chloride infusion on performance, serum, and urine metabolites of lactating dairy cows.
作者信息
Wang Kun, Nan Xuemei, Zhao Puyi, Liu Wei, Drackley James K, Liu Shijie, Zhang Kaizhan, Bu Dengpan
机构信息
State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China.
Department of Animal Sciences, University of Illinois, Urbana IL 61801, USA.
出版信息
Asian-Australas J Anim Sci. 2018 May;31(5):677-685. doi: 10.5713/ajas.17.0530. Epub 2017 Nov 3.
OBJECTIVE
The objective of the present study was to determine ammonium chloride tolerance of lactating dairy cows, by examining effects of negative dietary cation anion difference (DCAD) induced by ruminal ammonium chloride infusion on performance, serum and urine minerals, serum metabolites and enzymes of lactating dairy cows.
METHODS
Four primiparous lactating Chinese Holstein cows fitted with ruminal cannulas were infused with increasing amounts (0, 150, 300, or 450 g/d) of ammonium chloride in a crossover design. The DCAD of the base diet was 279 mEq/kg dry matter (DM) using the DCAD formula (Na + K - Cl - S)/kg of DM. Ammonium chloride infusion added the equivalent of 0, 128, 330, and 536 mEq/kg DM of Cl in treatments. According to the different dry matter intakes (DMI), the resulting actual DCAD of the four treatments was 279, 151, -51, and -257 mEq/kg DM, respectively.
RESULTS
DMI decreased linearly as DCAD decreased. Yields of milk, 4% fat-corrected milk, energy-corrected milk, milk fat, and milk protein decreased linearly as DCAD decreased. Concentrations of milk protein and milk urea nitrogen increased linearly with decreasing DCAD. Concentration of Cl- in serum increased linearly and concentration of PO43- in serum increased quadratically as DCAD decreased. Urine pH decreased linearly and calculated urine volume increased linearly with decreasing DCAD. Linear increases in daily urinary excretion of Cl, Ca, PO, urea N, and ammonium were observed as DCAD decreased. Activities of alanine aminotransferase, aspartate aminotransferase, and γ-glutamyl transferase in serum and urea N concentration in serum increased linearly as DCAD decreased.
CONCLUSION
In conclusion, negative DCAD induced by ruminal ammonium chloride infusion resulted in a metabolic acidosis, had a negative influence on performance, and increased serum enzymes indicating potential liver and kidney damage in lactating dairy cows. Daily ammonium chloride intake by lactating dairy cows should not exceed 300 g, and 150 g/d per cow may be better.
目的
本研究的目的是通过检查瘤胃注入氯化铵引起的负日粮阴阳离子差（DCAD）对泌乳奶牛生产性能、血清和尿液矿物质、血清代谢物及酶的影响，来确定泌乳奶牛对氯化铵的耐受性。
方法
选用4头安装有瘤胃瘘管的初产中国荷斯坦泌乳奶牛，采用交叉设计，分别注入递增剂量（0、150、300或450 g/d）的氯化铵。使用DCAD公式（Na + K - Cl - S）/kg干物质（DM）计算，基础日粮的DCAD为279 mEq/kg干物质。氯化铵注入量使各处理中Cl的含量分别相当于0、128、330和536 mEq/kg DM。根据不同的干物质采食量（DMI），四个处理的实际DCAD分别为279、151、-51和-257 mEq/kg DM。
结果
随着DCAD降低，DMI呈线性下降。随着DCAD降低，牛奶、4%脂肪校正乳、能量校正乳、乳脂肪和乳蛋白产量呈线性下降。乳蛋白和乳尿素氮浓度随着DCAD降低呈线性增加。随着DCAD降低，血清中Cl-浓度呈线性增加，血清中PO43-浓度呈二次曲线增加。尿液pH随着DCAD降低呈线性下降，计算得出的尿量随着DCAD降低呈线性增加。随着DCAD降低，每日尿中Cl、Ca、PO、尿素氮和铵的排泄量呈线性增加。随着DCAD降低，血清中丙氨酸氨基转移酶、天冬氨酸氨基转移酶和γ-谷氨酰转移酶的活性以及血清中尿素氮浓度呈线性增加。
结论
总之，瘤胃注入氯化铵引起的负DCAD导致代谢性酸中毒，对泌乳奶牛的生产性能产生负面影响，并增加了表明潜在肝肾损伤的血清酶活性。泌乳奶牛每日氯化铵摄入量不应超过300 g，每头牛150 g/d可能更佳。
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