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

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.

Body Characteristics, Performances and Protein Metabolism in Hy-Line Brown Hens Subject of Natural Moult

“…There was a little difference between the two moult modes, forced and spontaneous in the terms of feather coverage, but the appearance of the ovaries varied greatly (Zhang et al, 2022). According to Zhang et al (2022), generally, it would take 14-16 weeks to complete natural moult, whereas forced moult can be completed in 4 weeks for chickens without being affected by seasons.…”

“…There was a little difference between the two moult modes, forced and spontaneous in the terms of feather coverage, but the appearance of the ovaries varied greatly (Zhang et al, 2022). According to Zhang et al (2022), generally, it would take 14-16 weeks to complete natural moult, whereas forced moult can be completed in 4 weeks for chickens without being affected by seasons. Our monitoring confirms that the duration of natural moult in chickens in the industrial system exceeds the duration of the eight weeks of monitoring since at the end of the eight weeeks of surveillance, the naturally moulted hens had statistically significantly lower both laying percentage and body weight vs. control group (P = 0.009 and P = 0.043, respectively).…”

Chicken Hypothalamic and Ovarian DNA Methylome Alteration in Response to Forced Molting

“…In a previous study, FM achieved the rejuvenation effect in laying hens, and reproductive organs showed senescence under hunger stress and redeveloped after water supply and feeding were restored [ 29 , 32 ]. Further studies have revealed that this process is accompanied by the regulation of DNA methylation.…”

Fasting-Induced Molting Impacts the Intestinal Health by Altering the Gut Microbiota

“…The farming method, known as the fasting method, capitalizes on the reduced feed intake characteristic during the natural molting phase of poultry. It involves a period of fasting, water restriction, and adjustment of the lighting schedule to stimulate the flock, facilitating a prompt transition of laying hens into a new egg-laying cycle [ 3 , 6 ]. The hormone method entails injecting adrenal hormones, thyroid hormones, and progesterone into the muscle of poultry, resulting in a hormonal imbalance, perturbing the physiological equilibrium, and prompting laying hens to cease egg production and undergo molting [ 7 , 8 ].…”