Effects of dietary methionine on breast muscle growth, myogenic gene expression and IGF-I signaling in fast- and slow-growing broilers

Chao Wen,Yanmin Zhou,Xueying Jiang,Tian Wang,Liren Ding

doi:10.1038/s41598-017-02142-z

Abstract

This study investigated the responses of fast- (FG) and slow- (SG) growing broilers to dietary methionine (Met) status. The broilers were subjected to low (LM, 0.38 and 0.28 g/100 g), adequate (AM, 0.51 and 0.42 g/100 g) and high (HM, 0.65 and 0.52 g/100 g) Met during 1–21 and 22–42 d, respectively. Compared with the LM diets, the AM and HM diets increased body weight gain only in the FG broilers. The HM diets increased breast muscle yield only in the FG broilers, although insulin-like growth factor-I (IGF-I) concentration was increased in both strains of broilers. The HM diets increased mRNA levels of myogenic regulatory factors (MRF4, Myf5) and myocyte enhancer factor 2 (MEF2A and MEF2B) in the FG broilers, and increased MEF2A and decreased myostatin mRNA level in the SG broilers. Extracellular signal-regulated kinase (ERK) phosphorylation of breast muscle was increased by the HM diets in both strains of broilers, but mechanistic target of rapamycin (mTOR) phosphorylation was increased by the AM and HM diets only in the FG broilers. These results reflect a strain difference in broiler growth and underlying mechanism in response to dietary Met.

Highlights

Methionine (Met) is an essential amino acid for protein synthesis and a precursor of S-adenosylmethionine, the methyl donor for DNA methylation[1]
Our laboratory recently reported that MSTN, mechanistic target of rapamycin (mTOR) and FoxO4 were involved in the enhancement of breast muscle growth by Met in broilers with lower but not high hatching weight[12], suggesting that the responses to dietary Met were dependent on hatching weight of chicks
There was no significant difference in the insulin-like growth factor-I (IGF-I) concentration of breast muscle between the strains, supporting the previous study that reported similar IGF-I mRNA expression in breast muscle between FG and SG chickens when they were fed the same diet, significant differences were observed in live weight and breast muscle weight[14]

Summary

Introduction

Methionine (Met) is an essential amino acid for protein synthesis and a precursor of S-adenosylmethionine, the methyl donor for DNA methylation[1]. Our laboratory recently reported that MSTN, mTOR and FoxO4 were involved in the enhancement of breast muscle growth by Met in broilers with lower but not high hatching weight[12], suggesting that the responses to dietary Met were dependent on hatching weight of chicks. Whether these responses are affected by broiler strain remains unclear. The objective of this study was to compare the effects of dietary Met on growth performance, breast muscle yield and expression of myogenic genes and proteins associated with IGF-I signaling pathway in FG and SG chickens. Strain FG SG Met LM AM HM Strain×Met FG+LM FG+AM FG+HM SG+LM SG+AM SG+HM SEM P value Strain Met Strain×Met

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