日粮阴阳离子平衡对热应激奶牛血液生化指标的影响

Effects of Dietary Cation-anion Balance on Blood Biochemical Parameters of Heat Stressed Lactation Dairy Cows

试验旨在研究日粮阴阳离子平衡（dietary cation-anion balance,DCAB）对热应激条件下奶牛血液生化指标的影响。采用随机完全试验设计,选取75头健康的泌乳中期（104.8DIM±12DIM）中国荷斯坦奶牛,根据胎次、产奶量、体重相近的原则随机分为5组,试验Ⅰ、Ⅱ、Ⅲ、Ⅳ组和对照组分别饲喂DCAB值为195.76、186.68、177.77、166.94、239.12mEq/kg DM的日粮。试验期为67d,其中预试期7d,正试期60d。结果表明,试验Ⅰ、Ⅱ组的O2分压与试验Ⅲ、Ⅳ组和对照组相比,均有显著提高（P〈0.05）,但DCAB对PCO2、pH、HCO-3、TCO2、SATO2影响差异不显著（P〉0.05）;DCAB对奶牛血清中肌酸磷酸激酶（CK）产生了显著的影响（P〈0.05）,试验Ⅰ、Ⅱ组与试验Ⅲ、Ⅳ组和对照组相比,均有不同程度的降低,DCAB对奶牛血清中谷丙转氨酶（GPT）的影响差异不显著（P〉0.05）,但试验Ⅰ、Ⅱ组与试验Ⅲ、Ⅳ组和对照组相比,均有不同程度的升高,分别为13.98%、15.99%、10.77%和4.55%、6.40%、1.61%。奶牛血清中T4、T3、COR的浓度受DCAB的影响差异不显著（P〉0.05）,但对奶牛血清中尿素氮的浓度有显著影响（P〈0.05）,随着日粮DCAB值的升高,血清中尿素氮的浓度呈上升趋势,试验Ⅰ组最高。综合上述指标,在热应激条件下,泌乳中期奶牛饲喂DCAB值为186.68~195.76mEq/kg DM的日粮时对改善其健康较为适宜。

The objective of the present study was to investigate the effects of dietary cation anion balance on blood biochemi cal parameters of heat stressed lactation dairy cows. 75 middle lactation （104.8 DIM± 12 DIM） China Holstein cows were used in a randomized complete block design into five groups with similar parity, milk yield and weight, the groups I , Ⅱ , Ⅲ , IV and control group were adjusted the DCAB value by providing with different level cation anion salt, which were 195. 76, 186.68, 177.77, 166.94 and 239. 12 mEq/kg DM. The experiment was conducted for 67 days, including a 7 day adaptation period and a 60 day treatment period. The results showed that： compared with the groups Ⅲ , IV and control, the Po2 of the groups I , II have increased that were significantly different （P〈0.05） ;the effect of DCAB on dairy cows Pco2 ,pH,HCOa , TCO2 ,SAT% in blood was not significant difference （P〉0.05）. Compared with the groups Ill , IV and control group, the groups I , [l creatine phosphokinase （CK） in serum have decreased, the effect of DCAB on creatine phosphokinase （CK）in ser- um was significant difference （P〈0.05） ; the glutamie-pyruvie transaminase （GPT） in serum have increased, which increased 13.98%, 15.99%, 10.77% and 4.55%, 6.40%, 1.61% ,respectively, but there were not significant difference （P：〉0.05）. The content of T4, T3 and COR in serum were not significantly affected by change the DCAB value （P〉0.05） ,but effect of DCBA on the content of urea nitrogen in serum was significant difference （P〈0.05）, the concentrations of urea nitrogen in se rum have an increasing trend , with increasing DCAB values, concentrations of urea nitrogen in group I was the highest. Therefore, comprehensive index above, under the condition of heat stress, middle lactation cows feeding DCAB value of 186.68 to 195.76 mEq/kg DM diet is more suitable to improve its health.