Myostatin and Related Factors Are Involved in Skeletal Muscle Protein Breakdown in Growing Broilers Exposed to Constant Heat Stress.

Xiumei Li,Jinghai Feng,Minhong Zhang,Ying Zhou

doi:10.3390/ani11051467

Abstract

Simple SummaryOur results showed that constant heat stress could affect the expression of myostatin and related factors involved in skeletal muscle protein breakdown in growing broilers, resulting in a decrease in muscle protein deposition. These findings suggest a new strategy for regulating muscle protein breakdown in growing broilers, which could benefit the modern broiler industry in combating constant heat stress.Heat stress has an adverse effect on the development of poultry farming, which has always aroused great concern. This study was carried out to investigate the protein breakdown mechanism responsible for the suppressive effect of constant heat stress on muscle growth in growing broilers. A total of 96, 29-day-old, Arbor Acres male broilers were randomly divided into two groups, a thermoneutral control (21 ± 1 °C, TC) and a heat stress (31 ± 1 °C, HS) group, with six replicates in each group and eight birds in each replicate. The trial period lasted for 14 d, and the trial was performed at 60 ± 7% relative humidity, a wind speed of <0.5 m/s and an ammonia level of <5 ppm. The results showed that the average daily feed intake and average daily gain in the HS group were distinctly lower than those in the TC group (p < 0.05), whereas the HS group showed a significantly increased feed conversion ratio, nitrogen excretion per weight gain and nitrogen excretion per feed intake compared to the TC group (p < 0.05). In addition, the HS group showed a significantly reduced breast muscle yield and nitrogen utilization in the broilers (p < 0.05). The HS group showed an increase in the serum corticosterone level (p < 0.05) and a decrease in the thyroxine levels in the broiler chickens (p < 0.05) compared to the TC group, whereas the HS group showed no significant changes in the serum 3,5,3′-triiodothyronine levels compared to the TC group (p > 0.05). Moreover, the HS group showed increased mRNA expression levels of myostatin, Smad3, forkhead box O 4, muscle atrophy F-box and muscle ring-finger 1, but reduced mRNA expression levels of the mammalian target of rapamycin, the protein kinase B and the myogenic determination factor 1 (p < 0.05). In conclusion, the poor growth performance of birds under constant heat stress may be due to an increased protein breakdown via an mRNA expression of myostatin and related factors.

Highlights

Heat stress (HS) is a recognized long-term problem in the poultry farming industry, and its effect on poultry production performance is a common challenge in tropical and subtropical climatic conditions and even during the summer in temperate regions [1]
Whether the myostatin and related factors involved in skeletal muscle protein breakdown in growing broilers are affected by constant HS remains unclear
The data in the present study revealed that the HS group showed significantly reduced average daily feed intake (ADFI) and average daily gain (ADG) values and increased feed conversion ratio (FCR) values compared to the thermoneutral control (TC) group

Summary

Introduction

Heat stress (HS) is a recognized long-term problem in the poultry farming industry, and its effect on poultry production performance is a common challenge in tropical and subtropical climatic conditions and even during the summer in temperate regions [1]. According to the United States Department of Agriculture’s statistics, global chicken consumption reached 101.486 million tons in 2018. Poultry meat has seen a rise in its global demand because of its relatively high nutritional value, its low price and the lack of cultural or religious obstacles for its consumption [6]. Heat stress has a significant effect on the growth of breast muscle, which can greatly reduce the breast muscle yield [8,9,10,11,12] and result in a substantial economic loss

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