EFFECT OF COLD STRESSING CHICKEN EMBRYOS AND PREINCUBATION STORAGE ON HATCHABILITY, POST-HATCHING BODY WEIGHT, MORTALITY AND SEX RATIOS

Abstract

The effect of cold stressing 17-day chicken embryos was studied for 2 successive years. Exposing embryos to 21.2 C for up to 24 hr caused a nonsignificant reduction in hatchability, while 11.3 and 5.2 C caused a significant drop in hatchability. Egg size did not influence the effect of cold stress on hatchability. All three temperatures caused an increase in chick weight at hatching. Exposure to 21.2 C had no effect on 2, 4 or 6 week body weight except to reduce 2 week body weight of females. Prolonged exposure to 11.3 C generally reduced 4 and 6 week body weight. Exposing embryos to 5.2 C for 4 and 8 hr resulted in an increase in 4 and 6 week body weight, while 12 hr of exposure caused a reduction in 2, 4 and 6 week body weight. Post-hatching mortality was increased by exposure to 5.2 C for 12 and 16 hr in the first year, while in the second year prolonged exposure to all temperatures increased mortality. There was no effect of cold stress on sex ratios. Preincubation storage reduced hatchability, except in 1968 when there was an effect of cold stress on hatchability. Hatchability then increased as storage time increased. Post-hatching body weight and mortality were not affected by preincubation storage.