THE EFFECT OF LIGHTING AND TEMPERATURE ACCLIMATION DURING EMBRYO STAGE ON GROWTH, STRESS AND WELFARE OF BROILER CHICKENS
Project no. 21987 · Status: Kapanmış (Yayın bekleniyor) · 2020
Summary
<p>Heat stress is one of the most important challanges for poultry productin in hot climate regions. High environmental temperatures have negative effects on productivity of broilers. In this project , it was hypothesized that thermal acclimation (TA) during embryo stage together with photoperiodic lighting (LTA) may have positive additive effects on adaptation of broiler chicks to post-hatch environment and improve growth, immunity , and physiological and behavioral responses to acute heat stress at post-hatch. The project consisted of two experiments.</p><p><br></p><p>In the first experiment, the eggs were exposed to either optimal egg shell temperature (37.8ºC, Control) or to temperature acclimation using 1ºC higher eggshell temperature (38.8ºC ) for 6 h/day from 11 to 16 embryonic day (TA) . In the second experiment, the eggs were subjected to a 16 hours of light and 8 hours of darkness (16L: 8D) lighting schedule with optimum egg shell temperature (Light-control) or along with TA (LTA). Hatching performance, chick quality, growth perfromance, carcass traits, fear responses, immunity, blood corticosterone and behavioral responses of broilers to acute heat stress and pineal aralkylamine N-acetyltransferase (AANAT) gene expression were investigated.</p><p><br></p><p>Results from the study suggested that TA improved thermotolerance and increased resilience of broilers to acute heat stress at slaughter age. Furthermore, our study supplied first evidences that TA could modify melatonin hormone synthesis via increased pineal AANAT expression. This finding indicates that melatonin may also have a positive role in thermal acclimation during incubation.</p>