IMPROVEMENT OF THERMOTOLERANCE IN BROILER EMBRYOS


Güler H. C.

MEDITERRANEAN SUMMIT 4th INTERNATIONAL APPLIED SCIENCES CONGRESS, Girne, Cyprus (Kktc), 24 - 25 April 2021, pp.50-51

  • Publication Type: Conference Paper / Summary Text
  • City: Girne
  • Country: Cyprus (Kktc)
  • Page Numbers: pp.50-51

Abstract

The broiler industry has been subjected to intensive breeding processes since the 1950s to ensure a high growth rate and low feed consumption with high meat yield. However, while shaping the selection programs applied, consumer demands and the high-profit aim of the producers were kept at the forefront, as a result, significant metabolic defects (skeletal and circulatory system diseases, immunosuppression, etc.) occurred in broilers. As a result of the rapid development, today's broiler chickens have become quite sensitive to thermal stress (heat-cold). Thermal stress is an important source of oxidative damage in broilers and this situation causes significant economic losses. Epigenetic adaptation offers important opportunities to prevent these losses and to improve thermotolerance in broilers. Epigenetics is defined as the study of changes in gene function that are inherited mitotically or myotically and do not cause a change in DNA sequence. Epigenetic adaptation, a special type of phenotypic adaptation, aims to reprogram the living organism by gene expression against adverse environmental conditions likely to be encountered in later ages. Epigenetic adaptation mechanisms occur in the perinatal period and are initiated by learning processes in this period. Epigenetic adaptation pre-adapts chickens to an expected environment. It increases the survival probability of the chick between hatching and the development of physiological adaptation. Considering that broiler chicken production is carried out in different regions of the world and under very different environmental conditions, it is important to develop epigenetic adaptation in chick embryos against heat or cold. One of the most important criteria affecting hatchery success and productivity is considered to be the incubation temperature. Although the incubation temperature varies according to the species, as a general approach in broiler chickens, the optimum incubation temperature varies between 36.7-37.2°C. It is known that especially temperatures above 39.8°C or below 30.8°C affect the hatchability and chick quality negatively. Therefore, these limits should be considered while developing thermal adaptation using epigenetic mechanisms. For this purpose, it is possible to improve post-hatching thermotolerance and increase epigenetic thermal adaptation to heat or cold with heat manipulations performed at the incubation temperature. Thermal manipulations during embryonal development and growth aim to improve birds' capacity to encounter thermal challenges throughout their lifetime. This method consists of raising or lowering the incubation temperature during critical periods of embryonic development.