Influence of environmental and nutritional stressors on yolk sac utilization, development of chicken gastrointestinal system and its immune status.

摘要

The effects of everyday stress factors occurring on the first few days of the chick's life on the rate of yolk sac content utilization, immune status and growth of the animal's body and intestinal masses were investigated. The impact of stress was investigated during the first five days of the chick's life. The chicks were divided into five groups, each comprising 44 birds. The first group was exposed to moderate cold temperature (2-3 degrees C below the optimal temperature for the chick age). The second group was exposed to moderate heat (2-3 degrees C above the optimal temperature for the age). The third and fourth group were deprived of feed and drinking water for 12 hours and 24 hour, respectively. The fifth group was used as control. Birds in this group had optimal environmental conditions and received feed and drinking water immediately upon entering the trial. Ten chicks were taken every day and weighed. Blood samples were obtained for assessment of infectious bursal disease virus antibody titres using ELISA method. The chicks were then sacrified and their intestinal masses were weighed and the quantity of resorbed yolk was measured. The greatest body and intestinal masses were found in the control animals. The body and intestinal masses were lowest in the group which was denied water and food for 24 hours. The resorption of the yolk sac content was approximately equal in all the chick groups, but the resorption rate varied by days. The highest resorption was observed in the feed restricted groups. The high resorption was associated with the bird's energy requirements. The resorption of the remaining yolk was associated with feed intake. When energy requirements are not satisfied, the chick's body utilizes resorbed antibodies from the yolk remnants, as their glycoprotein composition is suitable for this purpose..