不同日粮模式对奶牛乳腺对氨基酸的摄取效率和乳腺动静脉激素变化规律的影响

摘要

试验研究不同日粮模式对奶牛乳腺对氨基酸的摄取效率和乳腺动静脉激素变化规律的影响。选用经产，体况良好，体重、产奶量、泌乳天数相近的荷斯坦奶牛10头，随机分为两组，分别饲喂混合粗饲料日粮（IMF）和低精料秸秆日粮（CS2）。饲喂第21d对尾动脉和乳静脉采集血样，测定血液中游离氨基酸和激素（COR、IGF-Ⅰ、HGH、LEP、INS和PRL）浓度。结果表明：（1）IMF组动脉血中COR、HGH、LEP、INS和PRL浓度分别比CS2组的高；IMF组静脉血中COR、IGF-Ⅰ、HGH、LEP和INS浓度分别比CS2组的高，除HGH差异显著外，其余均不显著；两组中乳静脉中IGF-Ⅰ和INS分别比尾动脉中的高。此外，HGH、INS和PRL在饲喂后2-3h达到一个高峰值，随后进行波动变化，而COR、IGF-Ⅰ和LEP比以上三种激素早达到高峰值，高峰值一般出现在饲喂后1-2h。（2）IMF组奶牛乳腺对Glu和Arg的摄取率显著高于CS2组，而对Cys的摄取率呈低于CS2组的趋势且为负值；对于Gly的摄取率两组均较低，且IMF组为负值；IMF组奶牛乳腺对和支链氨基酸（Val、Ile和Leu）的摄取率均高于CS2组，但差异不显著。以上研究结果表明，功能性氨基酸（Arg、Ser、Val、Ile和Leu等）和激素（COR、IGF-1、HGH、LEP、INS和PRL）在奶牛乳腺合成乳蛋白过程中起着重要作用。%This experiment was conducted to study the effects of different diets on extraction of amino acids and change lows of hormones of arterial and venous blood in the Mammary Gland of Dairy Cows. According to the principle of close weight, milk yield and lactation days, 10 holstein cows which were multiparity and had good body conditions were randomly assigned to 2 groups with 5 replicates. Two groups’ diets were respectively mixed forage (IMF) and low-concentrate and corn stover (CS2).Blood sample were colected at 21d for determination of the concentrations of free amino acids and hormones (COR, IGF - Ⅰ, HGH, LEP and INS and PRL) in milk venous and caudal arterial blood. The results showed that:(1) Concentrations of COR, HGH, LEP and INS and PRL in the arterial blood of group IMF were higher than group CS2 respectively.Compared with the concentrations of COR, IGF -Ⅰ, HGH, LEP and INS in the venous blood of group CS2, group IMF were al higher,the HGH was significant difference,and the rest were not.The concentrations of IGF -Ⅰ and INS in the venous blood was higher than in the arterial blood of two groups respectively. In addition,the concentrations of HGH,INS and PRL reached a peak after feeding 2 to 3 h, subsequently changed by rule of wave. However, the concentrations of COR, IGF -Ⅰ and LEP reached the peak earlier about one hour than those hormones.(2)The extractions of Glu and Arg in mammary gland of dairy cow of group IMF were significantly higher than group CS2, while the extraction of Cys was negative and trended lower than group CS2.For the extraction of Gly, two groups were low, and group IMF was negative. The extractions of branched chain amino acids (Val, Ile and Leu) in mammary gland of dairy cow of group IMF were al higher than group CS2, but had no significant difference .Above results indicated that the functional amino acids (Arg, Ser, Val, Ile and Leu, etc.) and hormones (COR, IGF-1, HGH, LEP and INS and PRL) played an important role in the process of the synthesis of milk protein in mammary gland of dairy cow.