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乳中蛋白质和氨基酸成分的改变影响着乳制品的营养和物理性质。研究结果表明,静脉灌注胰高血糖素通过促进血中氨基酸的葡萄糖异生作用,增强肝中葡萄糖的合成,从而降低了乳中蛋白质的产量和含量。本试验旨在研究胰高血糖素对乳蛋白的影响。试验1:以8头荷斯坦奶牛为试验动物,自由饲喂基础上灌注胰高血糖素10mg/d,连续灌注14d;试验2:以7头荷斯坦奶牛为试验动物,限饲基础上灌注胰高血糖素10mg/d,连续灌注14d;试验3:以4头瑞士褐牛为试验动物,分别以5、10mg/d的剂量灌注胰高血糖素2d。试验开始前1d,试验期的第1天,试验期的最后1d及试验期后第1天采样,并且将试验期测得的乳蛋白和氨基酸组成与试验开始前和试验结束后样品中含量相比较。结果表明,胰高血糖素的灌注降低了乳蛋白的产量和含量,分别为(0.2±0.05)kg/d和(4±0.4)g/L;同时改变了乳蛋白的组成,提高了κ-酪蛋白含量(1.68%±0.27%)。总的来说,胰高血糖素的灌注提高了κ-酪蛋白和αs2酪蛋白(1.34%±0.51%)的比例,降低了αs1酪蛋白(3.83%±1.75%)和α乳蛋白(0.91%±0.32%)的比例。胰高血糖素的灌注提高了乳中甘氨酸(0.26%±0.11%)的比例,对乳组成的其它氨基酸影响较小。结果显示,乳蛋白合成受氨基酸和胰岛素的利用率等多种因素的影响。
Changes in milk protein and amino acid composition affect the nutritional and physical properties of dairy products. The results show that intravenous infusion of glucagon can enhance the synthesis of glucose in the liver by promoting the gluconeogenesis of amino acids in the blood, thereby reducing the protein yield and content in the milk. The purpose of this study was to investigate the effect of glucagon on milk protein. Test 1: Eight Holstein cows were used as experimental animals. Glucagon was infused 10 mg / d on the basis of free feeding for 14 days. Experiment 2: Seven Holstein cows were used as experimental animals, Glucagon 10mg / d, continuous infusion 14d; Test 3: 4 Swiss brown cattle as experimental animals, respectively, at a dose of 5,10 mg / d glucagon infusion 2d. The first day before the test, the first day of the test period, the last day of the test period and the first day after the test period were sampled. The milk protein and amino acid composition measured during the test period were compared with those before and after the test Compare The results showed that the glucagon perfusion decreased the yield and content of milk protein (0.2 ± 0.05) kg / d and (4 ± 0.4) g / L, respectively, and changed the composition of milk protein and increased the expression of κ- Casein content (1.68% ± 0.27%). In conclusion, glucagon perfusion increased the ratio of κ-casein to αs2 casein (1.34% ± 0.51%), decreased αs1 casein (3.83% ± 1.75%) and α-lactoprotein (0.91% ± 0.32%). Glucagon perfusion increased the proportion of glycine in milk (0.26% ± 0.11%), but had less effect on the other amino acids in milk composition. The results showed that the synthesis of milk protein by the amino acid and insulin utilization rate and other factors.