Search

The main objective of this study was to elucidate the effect of short- term exposure of Japanese quail eggs to acute high incubation temperature on embryonic development and on the ability of post- hatched chicks to cope with subsequent heat stress conditions during the growing period. A total of 998 Japanese quail eggs were divided into two groups, the first group (470 eggs) was maintained at the recommended incubation temperature (37.5 °C), while the second group (528 eggs) was exposed to 39.5 °C for two hours at days 3, 7 and 13 of embryogenesis. After hatching, chicks from each incubation temperature were randomly assigned to four dietary treatments, a control, a high-energy (+150 kcal ME/kg diet more than the recommended level); a high-lysine (10% more than in the control diet) and a vitamin C supplemented diet. During the experimental period all of the quail were fed ad libitum and they received similar hygienic and managerial conditions. The rearing temperature was 32±2 °C during the entire experimental period. Pre-hatching exposure of eggs to 39.5 °C did not significantly affect the post-hatching body weight and weight gain during the growing period. While, vitamin C or high-energy diet increased it. Body temperature, respiration rate (RR) and the relative weights of the thymus, spleen and bursa of Fabricius were not significantly affected by the pre-hatching temperature or the post-hatching dietary treatments. However, the high-energy and vitamin C diets caused obvious decreases in RR at 4 weeks of age. Pre-hatching heat treatments caused a slight increase in the plasma triiodothyronine (T3) and plasma thyroxine (T4) concentrations, however, was significantly decreased by both the pre- hatching temperature and post- hatching dietary treatments at 6 weeks of age. Based on the above results, it was concluded that pre-hatching exposure of quail eggs to high temperature and post-hatching feeding of a high-energy or vitamin C supplemented diet can be recommended for alleviating the deleterious effects of heat stress during the growing period. [ABSTRACT FROM AUTHOR]