Dietary protein re-alimentation following restriction improves protein deposition via changing amino acid metabolism and transcriptional profiling of muscle tissue in growing beef bulls  

作　　者：Jiaqi Wang Chun Shen Guangyong Zhao Mark D.Hanigan Mengmeng Li 

机构地区：[1]State Key Laboratory of Animal Nutrition and Feeding,College of Animal Science and Technology,China Agricultural University,Beijing 100193,China [2]School of Animal Sciences,Virginia Tech,Blacksburg,VA 24060,USA

出　　处：《Animal Nutrition》2024年第4期117-130,共14页动物营养(英文版)

基　　金：supported by the National Natural Science Foundation of China(grant no.32102573);the 315 Talent Project at China Agricultural University.

摘　　要：This study aimed to develop a compensatory growth model using growing beef cattle by changing dietary protein and to investigate the underlying mechanisms of compensatory protein deposition in muscle tissue.Twelve Charolais bulls were randomly assigned to one of two groups with two periods:1)a control group(CON)fed a 13%crude protein(CP)diet for 6 weeks;2)a treatment group(REC)fed a 7%CP diet for 4 weeks(restriction period)and fed a 13%CP diet in the following 2 weeks(re-alimentation period).Growth performance,digestibility,nitrogen balance,targeted metabolomics of amino acids(AA)in plasma,and transcriptional profiling in muscle tissue were analyzed.Protein restriction decreased average daily gain(ADG;P<0.05),while protein re-alimentation increased ADG relative to the CON(P<0.05).Compared to the CON,REC reduced retained N(P<0.05),and protein re-alimentation increased retained N and N utilization efficiency(P<0.05),due to reduced urinary urea,hippuric acid,and creatinine excretions(P<0.05).Ruminal NH3-N in the REC was lower than that in the CON in the protein re-alimentation period(P<0.05).However,there was no difference in microbial protein and plasma urea nitrogen concentrations.Dietary protein restriction decreased plasma valine and aspartic acid concentrations relative to the CON(P<0.05),and increased proline and 3-methyl-L-histidine concentrations(P<0.05).After dietary protein re-alimentation,REC increased plasma citrulline concentrations(P<0.05).The transcriptional profiling revealed that REC upregulated the AA transporter SLC3A1,and protein re-alimentation downregulated SLC7A8 in the muscle cell membrane.Within the muscle cell,upregulated cytosolic arginine sensor for mTORC1 subunit 2(CASTOR2)inhibited protein synthesis by inhibiting the mammalian target of rapamycin complex 1 phosphorylation in the protein restriction period,while DNA-damage-inducible transcript 4(DDIT4)activated the mTOR signaling pathway and promoted protein synthesis in the protein re-alimentation period.In summary,the targeted metabolo

关 键 词：Amino acid Beef cattle Compensatory growth METABOLISM Protein 

分 类 号：O62[理学—有机化学]