High rumen degradable starch decreased goat milk fat via trans-10,cis-12 conjugated linoleic acid-mediated downregulation of lipogenesis genes,particularly,INSIG1  

作　　者：Lixin Zheng Shengru Wu Jing Shen Xiaoying Han Chunjia Jin Xiaodong Chen Shengguo Zhao Yangchun Cao Junhu Yao 

机构地区：[1]College of Animal Science and Technology,Northwest A&F University,Yangling 712100,Shaanxi,China [2]State Key Laboratory of Animal Nutrition,Institute of Animal Sciences,Chinese Academy of Agricultural Sciences,Beijing 100193,China

出　　处：《Journal of Animal Science and Biotechnology》2020年第3期805-818,共14页畜牧与生物技术杂志（英文版）

基　　金：This research was financially supported by the National Key Research and Development Program of China(award number:2017YFD0500500);the Science&Technological Project of Shaanxi Province,China(award number:2017 TSCXL-NY-04-01).

摘　　要：Background:Starch is an important substance that supplies energy to ruminants.To provide sufficient energy for high-yielding dairy ruminants,they are typically fed starch-enriched diets.However,starch-enriched diets have been proven to increase the risk of milk fat depression(MFD)in dairy cows.The starch present in ruminant diets could be divided into rumen-degradable starch(RDS)and rumen escaped starch(RES)according to their different degradation sites(rumen or intestine).Goats and cows have different sensitivities to MFD.Data regarding the potential roles of RDS in milk fat synthesis in the mammary tissue of dairy goats and in regulating the occurrence of MFD are limited.Results:Eighteen Guanzhong dairy goats(day in milk=185±12 d)with similar parity,weight,and milk yield were selected and randomly assigned to one of three groups(n=6),which were fed an LRDS diet(Low RDS=20.52%),MRDS diet(Medium RDS=22.15%),or HRDS diet(High RDS=24.88%)for 5 weeks.Compared with that of the LRDS group,the milk fat contents in the MRDS and HRDS groups significantly decreased.The yields of short-,mediumand long-chain fatty acids decreased in the HRDS group.Furthermore,increased RDS significantly decreased ruminal B.fibrisolvens and Pseudobutyrivibrio abundances and increased the trans-10,cis-12 conjugated linoleic acid(CLA)and trans-10 C18:1 contents in the rumen fluid.A multiomics study revealed that the HRDS diet affected mammary lipid metabolism down-regulation of ACSS2,MVD,AGPS,SCD5,FADS2,CERCAM,SC5D,HSD17B7,HSD17B12,ATM,TP53RK,GDF1 and LOC102177400.Remarkably,the significant decrease of INSIG1,whose expression was depressed by trans-10,cis-12 CLA,could reduce the activity of SREBP and,consequently,downregulate the downstream gene expression of SREBF1.Conclusions:HRDS-induced goat MFD resulted from the downregulation of genes involved in lipogenesis,particularly,INSIG1.Specifically,even though the total starch content and the concentrate-to-fiber ratio were the same as those of the high-RDS diet,the low and medium RDS diets did

关 键 词：Dairy goat INSIG1 Milk fat depression Rumen degradable starch Trans-10 cis-12 CLA 

分 类 号：S827[农业科学—畜牧学]