Timing Is Everything-The High Sensitivity of Avian Satellite Cells to Thermal Conditions During Embryonic and Posthatch Periods.

Orna Halevy

doi:10.3389/fphys.2020.00235

Abstract

Myofiber formation is essentially complete at hatch, but myofiber hypertrophy increases posthatch through the assimilation of satellite cell nuclei into myofibers. Satellite cell proliferation and differentiation occur during the early growth phase, which in meat-type poultry terminates at around 8 days posthatch. Thus, any factor that affects the accumulation of satellite cells during late-term embryogenesis or early posthatch will dictate long-term muscle growth. This review will focus on the intimate relationship between thermal conditions during chick embryogenesis and the early posthatch period, and satellite cell myogenesis and pectoralis growth and development. Satellite cells are highly sensitive to temperature changes, particularly when those changes occur during crucial periods of their myogenic activity. Therefore, timing, temperature, and duration of thermal treatments have a great impact on satellite cell activity and fate, affecting muscle development and growth in the long run. Short and mild thermal manipulations during embryogenesis or thermal conditioning in the early posthatch period promote myogenic cell proliferation and differentiation, and have long-term promotive effects on muscle growth. However, chronic heat stress during the first 2 weeks of life has adverse effects on these parameters and may lead to muscle myopathies.

Highlights

Vertebrates are born or hatch with a defined number of myofibers in the muscle
This review will focus on the implications of environmental conditions, thermal conditions, during embryogenesis and early posthatch periods, for Abbreviations: BW, body weight; SC, satellite cell; Ta, ambient temperature; Tb, body temperature; TC, thermal conditioning; TM, thermal manipulation
While TMs between E8 and E10 for 3 h daily did not have any promotive effect on these parameters (Collin et al, 2007), intermittent TM for 12 h/day between E8 and E16 had a long-lasting effect on thermotolerance, BW and pectoralis muscle growth (Loyau et al, 2014) up to 70 days posthatch (Piestun et al, 2013)

Summary

Introduction

Vertebrates are born or hatch with a defined number of myofibers in the muscle. Muscle growth will involve mainly growth in myofiber size (i.e., hypertrophy), where there is a large increase in the synthesis of contractile and regulatory proteins. In a follow-up study, it was demonstrated that mild TC on day 3 boosts the number of SCs in the pectoralis muscle and accelerates their differentiation on later days, resulting in higher pectoral muscle growth until marketing (Halevy et al, 2001).

Results

Conclusion