采食后奶牛瘤胃短链脂肪酸及其吸收相关蛋白表达的研究

本试验旨在研究奶牛采食前后瘤胃中短链脂肪酸(SCFA)浓度的变化及其吸收相关蛋白表达量的差异。试验选用3头体重(720±30)kg且装有瘘管的健康荷斯坦牛(动物伦理审查编号为SXAU-EAW-2019-C002013),采食精粗比为40:60的日粮(10kg),试验预试期10d,于第11天饲喂前开始取样,采用气相色谱法检测奶牛采食前(0 h)和采食后(1、2、3、4、5、6、7、8 h)瘤胃液中SCFA浓度;并采用荧光定量PCR方法检测瘤胃上皮组织中与SCFA吸收相关的蛋白表达量。结果表明:在采食后1 h奶牛瘤胃中SCFA浓度最高(P<0.05);在采食后一段时间内(2~5h)与SCFA吸收相关蛋白表达量上调(P<0.05),AE2、MCT1基因表达量均在5 h最高,PAT1、NHE3基因表达量均在4 h最高,MCT4基因表达量在4、5、6h均较高,NHE1基因表达量在2h达到最高;AE2、MCT1、MCT4、NHE1基因表达量与SCFA浓度负相关或正相关(P<0.05),AE2、MCT1、MCT4基因表达量与瘤胃内pH正相关(P<0.05)。以上结果初步揭示,在采食后一定时间内,瘤胃中与SCFA吸收相关蛋白表达受SCFA浓度和pH的调节。

Study on the Short Chain Fatty Acids and Expression of Absorption Related Protein in the Rumen of Dairy Cattle after Feeding

In this study,we compared the changes of short chain fatty acid(SCFA)concentration and their absorption related proteins in the rumen of dairy cattle before and after feeding,and explored the variation rules of SCFA absorption related proteins with the concentration of SCFA in rumen when the concentrate to forage ratio was 40:60(10 kg).The concentrations of short chain fatty acids in rumen fluid of dairy cattle before feeding(0 h)and after feeding 1,2,3,4,5,6,7,8 h were detected by gas chromatography,and the expression of SCFA absorption related protein in rumen epithelial tissue was detected by fluorescence quantitative PCR.The results showed that the concentration of SCFA in rumen was the highest at 1 h after feeding(P<0.05).In a period of time(2~5 h)after feeding,the expression of protein related to SCFA absorption was significantly up-regulated(P<0.05),AE2 gene expression was the highest at 5 h,PAT1 gene expression was the highest at 4 h,MCT1 expression was the highest at 5 h,and MCT4 gene expression was higher at 4 h,5 h and 6 h.The expression of NHE1 gene reached the highest level at 2 h.The expression level of NHE3 gene was the highest at 4 h.AE2,MCT1,MCT4 and NHE1 gene expression were significantly negatively correlated(P<0.05)and positively correlated with SCFA concentration(P<0.05).AE2,MCT1,and MCT4 were positively correlated with rumen pH(P<0.05).These results preliminarily revealed that the expression of SCFA absorption related proteins in rumen was regulated by SCFA concentration and pH in a certain time after feeding,which laid a foundation for further study of SCFA concentration and SCFA absorption mechanism in rumen under different feeding conditions and physiological conditions.