Akademik Veri Yönetim Sistemi
MEDITERRANEAN SUMMIT 4th INTERNATIONAL APPLIED SCIENCES CONGRESS, Girne, Kıbrıs (Kktc), 24 - 25 Nisan 2021, ss.50-51
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.