断奶应激对犊牛血液生化、免疫和内分泌的影响

选择体质量和出生日期接近的26头犊牛,其中6头母犊,20头公犊。10日龄开始补充苜蓿干草、精饲料自由采食,60日龄断奶。分别在断奶前（-1d）和断奶后1,3,5,7,14d采集血液,测定血清中代谢物、激素及免疫球蛋白含量的变化情况。结果表明,断奶影响犊牛的消化代谢,血清中葡萄糖、总蛋白、尿素氮、甘油三酯含量变化显著（P〈0.01）。断奶造成犊牛血清皮质醇、急性反应蛋白、T3、T4、乳酸脱氢酶、碱性磷酸酶、溶菌酶显著变化（P〈0.01）,使免疫球蛋白、γ-IFN、IL-1含量有不同程度下降（P〉0.05）。因此,断奶不仅降低了犊牛的免疫力,而且对犊牛产生了严重的应激反应。

Effects of weaning stress on blood biochemical indicators,immunity and endocrine of dairy calves

Twenty-six Holstein calves（six heifers and twenty bull） were selected with the similar body weight and birthday. All the calves began to be fed alfalfa hay at 10 days of age and concen- trate was supplied ad libiturn. The calves were weaned at the age of 60 d. Blood sample was col- lected at the preceding weaning（-1 d） and postweaning 1,3,5,7 and 14 d. The changes of metab- olites,hormone and immunoglubin in serum were tested. The results showed that the contents of serum glucose, total protein, urea nitrogen, triglyceride were changed significantly with weaning （P〈0. 01）. The weaning significantly affected the cortisol, acute-protein, 73 , T4 , LDH, ALP and LZM in serum of calves（P〈0.01） ,but tended to decrease serum immunoglobulin,7-IFN and IL-1 levels（P〉0.05）. Therefore,weaning not only weakened the immunity, but also produced serious stress reaction for the calves.