Abstract
Heat stress (HS) affects the production performance in chickens and causes economic loss to the producers. Most of the studies have been conducted on and for the welfare of broilers. We still lack information on the physiological parameters being affected during chronic heat stress in layers. To fill this gap, the present study evaluated the effect of heat stress (induced in the chamber) during the prelaying period (21–23 weeks) on plasma levels of the hormones leptin and ghrelin and GH and expression of the respective receptors and heat stress markers. Three groups were considered, one at room temperature (CR) and the other two groups (SH and CH) subjected to heat stress at 39°C for four hours for three weeks (21–23 weeks of age). The SH group (SH) feed was supplemented with fermented yeast culture (FYC, 700 mg/kg), whereas the CH group was devoid of it. After that, all the groups were shifted to shed under natural ambient conditions till 31 weeks of age. Studies were restricted to production performance only. Feed offered without yeast culture (CH group) had a smaller concentration of plasma hormones (P < 0.01) and increased expression fold of the hormone receptors (P < 0.01). Further, the group also presented higher liver AMP kinase enzyme, plasma MDA (malondialdehyde), and cholesterol concentrations. These changes likely explained the decrease in feed intake and the CH group's body weight and further reduced the production performance during the laying period. Supplementation with FYC to birds had an opposite effect on the above-mentioned parameters, reducing HS effects. In summary, supplementation with FYC (700 mg/kg) maintained physiological parameters as in the CR group under HS conditions and negated adverse effects on parameters both before and during laying periods.
Highlights
Heat stress (HS) affects the production performance in chickens and causes economic loss to the producers
The present study evaluated the effect of heat stress during the prelaying period (21–23 weeks) on plasma levels of the hormones leptin and ghrelin and GH and expression of the respective receptors and heat stress markers. ree groups were considered, one at room temperature (CR) and the other two groups (SH and CH) subjected to heat stress at 39°C for four hours for three weeks (21–23 weeks of age). e second (CH) and third (SH) group (SH) feed was supplemented with fermented yeast culture (FYC, 700 mg/kg), whereas the CH group was devoid of it
Even in layer reports that are available with respect to amelioration of heat stress, they have concentrated on the effects of supplement only during the laying period. e present work describes the effect of applied heat stress (HS) during prelaying on the physiological parameters, especially the effect on mentioned hormones and their receptors, which has not been reported, and their posteffect in terms of decreased production performance has been not reported. e present study reports that a supplement like FYC which has not been used for alleviation of heat stress is able to increase the production performance by reversing the effects of HS through modulation of hormones, metabolites, enzymes, and gene expression
Summary
Heat stress (HS) affects the production performance in chickens and causes economic loss to the producers. We still lack information on the physiological parameters being affected during chronic heat stress in layers To fill this gap, the present study evaluated the effect of heat stress (induced in the chamber) during the prelaying period (21–23 weeks) on plasma levels of the hormones leptin and ghrelin and GH and expression of the respective receptors and heat stress markers. E present study reports that a supplement like FYC which has not been used for alleviation of heat stress is able to increase the production performance by reversing the effects of HS through modulation of hormones, metabolites, enzymes, and gene expression. E reports regarding the effects of heat stress on hormones in broilers are many, but studies reflecting the impact on the mentioned parameters in layers are lacking Another essential parameter affected by heat stress is the AMP kinase (AMPK) enzyme. Another essential parameter affected by heat stress is the AMP kinase (AMPK) enzyme. e AMPK is one of the primary cellular energy sensors [24] and an intracellular low-energy warning system [25]
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