回乳期奶牛血清GH、INS、HC、TGF-β1和IGF-1含量变化

Changes of GH,INS,HC,TGF-β1 and IGF-1 levels in cows' serum during milk withdrawal period

为探究回乳期奶牛血清中生长激素(GH)、胰岛素(INS)、氢化可的松(HC)、转化生长因子β1(TGF-β1)和胰岛素样生长因子1(IGF-1)含量的变化及其相关性。试验选择规模化奶牛场日产奶量为(15.43±2.10)kg,即将干乳的妊娠后期健康中国荷斯坦奶牛20头。干乳开始当天记为第0天,分别采集第0、1、3、5、7、9和11天奶牛尾静脉血,ELISA法检测血清中GH、INS、HC、TGF-β1和IGF-1含量并对结果进行统计学处理,分析其在奶牛回乳过程中的变化规律及其相关性。结果显示,回乳期奶牛血清GH、INS、HC和TGF-β1含量在第0至1天变化不显著(P>0.05);血清GH和HC含量第3至11天依次降低且差异均极显著(P<0.01),其中血清HC含量第3天极显著高于其余各天(P<0.01);血清INS含量第3至11天依次升高且差异均极显著(P<0.01);血清TGF-β1含量第3至11天差异性均不显著(P>0.05);血清IGF-1含量依次呈阶梯式下降趋势,第0天和第1天、第3天和第5天、第7天和第9天、第9天和第11天之间均差异不显著(P>0.05),但第0至1天、第3至5天、第7至11天3阶段之间差异极显著(P<0.01)。回乳期奶牛血清GH、INS、TGF-β1和IGF-1含量变化两两间呈极显著相关(P<0.01);HC含量变化与GH、INS和IGF-1含量变化均呈极显著相关(P<0.01),与TGF-β1含量变化呈显著负相关(P<0.05)。

In order to explore the changes and correlation among the levels of growth hormone （ GH） , insulin （INS） , hydrocortisone （ HC） , TGF-β1 and IGF-1 in cows, serum during the period of milk withdrawal. Twenty healthy Chinese Holstein cows in late pregnancy that gave （15. 43 ±2. 10） kg milk per day were used, which were ready to dry milk. The day when cows began to dry milk was recorded as the 0 d. The cows, venous blood from the tail on the day 0, 1, 3, 5, 7, 9 and 11 were collected. ELISA was used to evaluate the levels of GH, INS, HC, TGF-β1 and IGF-1 in serum to analyze the changes and correlation among them. The results showed that, during the period of milk withdrawal, the changes of GH, INS, HC and TGF-pl levels in serum were not obvious from the day 0 to the day 1 （ P 〉 0.05 ）. The levels of GH and HC in serum were both on the decline and had significant differ-ence from the day 3 to the day 11 （P 〈0.01） , and the levels of GH in serum on the day 3 was significantly higher than those on the other days （ P 〈 0.01）. The levels of INS in serum was on the rise and had significant （ P 〈 0.01） difference from the day 3 to the day 11, while the levels of TGF-β1 in serum had no significant （P 〉0. 05） differ-ence from the day 3 to the day 11. The levels of IGF-1 in serum showed downward trend in ladder type, and the difference among levels of IGF-1 in serum on the day 0 and day 1, day 3 and day 5 , day 7 and day 9, day 9 and day 11 were not obvious （P 〉 0.05 ） , while IGF-1 levels among 0-1 d, 3-5 d and 7-11 d had significant （P 〈 0.01 ） difference. There was significant （P 〈0.01） correlation among the levels of GH, INS, TGF-β1 and IGF-1 in cows serum separately during the period of milk withdrawal. The HC levels showed significant （P 〈0. 01） correlation with GH, INS and IGF-1 levels, while it showed significant （P〈0. 05 ） negative correlation with TGF-β1 levels.