Effects of early environmental stresses on chicken body weight, antibody response to RBC antigens, feed efficiency, and response to fasting.

Stress early in life (SEL) by either overheating or water deprivation altered the responses of 4-to-18-week-old chickens selectively bred for high (HA) or low (LA) antibody response to sheep RBC. When unstressed, HA birds weighed more than LA birds. Following SEL, LA birds weighed more than HA birds. Antibody response following SEL was decreased in HA birds and increased in LA birds. Both SEL and adaptation to handlers (AH) decreased the deleterious effects of fasting on antibody response to RBC antigens. Chickens subjected to SEL had a lower rate of gain following fasting. Adaptation to handlers tended to increase antibody response more in HA than in LA birds, while SEL tended to increase antibody response more in LA than in HA birds. Feed efficiency (FE) was increased by AH. A SEL resulted in increased FE of unadapted birds and decreased the FE of AH birds.