Understanding Transcriptomic and Serological Differences between Forced Molting and Natural Molting in Laying Hens.

Tongyu Zhang,Zhonghua Ning,Xueze Lv,Haiying Li,Weifang Yang,Yu Chen,Huie Wang,Liang Wang,Lujiang Qu,Changqing Qu,Junhui Wen,Yaxiong Jia

doi:10.3390/genes13010089

Abstract

Molting is natural adaptation to climate change in all birds, including chickens. Forced molting (FM) can rejuvenate and reactivate the reproductive potential of aged hens, but the effect of natural molting (NM) on older chickens is not clear. To explore why FM has a dramatically different effect on chickens compared with NM, the transcriptome analyses of the hypothalamus and ovary in forced molted and natural molted hens at two periods with feathers fallen and regrown were performed. Additionally, each experimental chicken was tested for serological indices. The results of serological indices showed that growth hormone, thyroid stimulating hormone, and thyroxine levels were significantly higher (p < 0.05) in forced molted hens than in natural molted hens, and calcitonin concentrations were lower in the forced molted than in the natural molted hens. Furthermore, the transcriptomic analysis revealed a large number of genes related to disease resistance and anti-aging in the two different FM and NM periods. These regulatory genes and serological indices promote reproductive function during FM. This study systematically revealed the transcriptomic and serological differences between FM and NM, which could broaden our understanding of aging, rejuvenation, egg production, and welfare issues related to FM in chickens.

Highlights

Feathers are an integral part of the life of all birds and provide protection, insulation, and strength during flight and courtship
The age of Forced molting (FM) chickens was 469 and 527 days, with the study lasting for 58 days, while during the two Natural molting (NM) periods, the age of hens were 572 days and 721 days, lasting for 149 days
FM was similar to NM in the pattern of changed feather coverage, but the time of molting and egg-laying rate (ELR) were greatly different, resulting from remarkable differences in intrinsic hormone and genetic regulation

Summary

Introduction

Feathers are an integral part of the life of all birds and provide protection, insulation, and strength during flight and courtship. Natural molting (NM) occurs in birds as an adaptive mechanism to climate change [1]. The function of feathers is mainly limited to coping with heat stress in special environments and avoiding close scratches during feeding. Molting in laying hens is a natural and orderly process, similar to that in other birds. Under the direct or indirect action of hormones such as thyroxine, estrogen, and testosterone, wing feathers are the first to molt, followed by body feathers [2]. Feathers from the abdomen and back of chickens are shed the most

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