摘要
为了解高精料日粮对泌乳奶牛乳产量的影响,选择12只健康经产奶牛,分别饲喂精粗比为40∶60(对照组)和60∶40(高精料组)的日粮,试验期12周,每周监测乳产量。试验期间每周采集血液样品用于测定外周血生长激素(GH)和胰岛素样生长因子1(IGF-1)含量;试验结束,采集瘤胃液置-70℃保存待测,肝脏和乳腺组织于液氮速冻后置-70℃保存待测。结果表明,高精料日粮的饲喂显著降低了瘤胃pH(P<0.05);奶牛外周血GH含量和IGF-1含量从第7周开始显著降低(P<0.05);肝脏组织中生长激素受体(GHR)、蛋白质酪氨酸激酶2(JAK2)、信号传导与转录激活子5A(STAT5A)及信号传导与转录激活子5B(STAT5B)mRNA表达水平显著下调(P<0.05);乳腺组织中,胰岛素样生长因子1受体(IGF-1R)mRNA表达水平显著下调(P<0.05)。结果提示,长期饲喂高精料日粮会降低血液中GH和IGF-1含量,抑制GH-IGF-1轴的基因表达及关联的JAK2-STAT5信号途径的相关基因表达,从而减少了乳产量。
In order to investigate the effect of feeding high concentrate diets on milk production, 12 healthy multiparous dairy cows in mid-lactation were randomly divided in to two groups.One receiving a diet with normal control （concentrate. forage=40 ： 60） as the NC group,and another receiving a high concentrate diet treatment （concentrate. forage=60 ： 40） as the HT group.The experiment lasted for 12 weeks and milk production was monitoring every week.At the end of experiment,the rumen liquids were sampled and stored at -70℃ ,also liver and mammary tissue were sampled and stored at -70℃ by liquid nitrogen flash freezer for later gene expression analysis.During the experiment, the plasma samples were collected every week for determining the GH and IGF-1 concentrations. The results showed that the ruminal pH, milk yield,the plasma GH and IGF-1 concentrations of HT group were significantly decreased （P〈0.05） after 7 weeks,compared with the NC group. The gene expressions of growth hormone receptor （GHR）, proteintyrosine kinase 2 （JAK2）, signal transducer and activator of transcription 5A （STAT5A） and signal transducer and activator of transcription 5B （STATSB） in liver,insulin-like growth factor 1 receptor （IGF-1R） in mammary gland,respectively,showed significant down regulation in the HT group compared with the NC group （P〈0.05）.These results suggest that prolonged feeding of a high concentrate diet could reduces the plasma GH and IGF-1 concentrations, down regulate the mRNA expression levels of GH-IGF-1 axis genes and associated with JAK2-STAT5 pathway genes,resulting in a decline in the milk yield.
出处
《动物医学进展》
北大核心
2017年第8期57-62,共6页
Progress In Veterinary Medicine
基金
福建农林大学金山学院科研启动基金项目(Z150701)
