AGE AND PSYCHOGENIC FACTORS IN RESPONSE TO FOOD-DEPRIVATION AND REFEEDING IN WHITE-LEGHORN CHICKENS

Physiology, behavior, and egg production mere measured in White Leghor n chickens (21 and 329 days of age) subjected to (1) nn libitum feedin g (AL); (2) food withdrawal for 48 h, with the provision oi sand (SAND ); (3) food withdrawal for 48 h (NO FOOD); or (4) food withdrawal for 48 h, imposed by blocking access to food by a wire mesh which allowed visual and olfactory cues (WIRE). Fasting-elicited elevation in H/L ra tios was evident by 24 h. Following 48 h of fasting, WIRE chickens had the highest H/L ratios followed by SAND, NO FOOD, and AL. Within 36 h of refeeding, older chickens had recovered from fasting-induced stres s but H/L ratios of younger ones from WIRE and SAND treatments showed erratic fluctuations. When released to ad libitum feeding, food intake of older chickens varied according to prior treatment and remained th e same during both days of replenishment, whereas all younger ones con sumed similar amounts of feed with an intake higher on the second than first day of refeeding. Fasted chickens displayed prominent behaviora l responses with occasional age-related discrepancies. Chickens subjec ted to WIRE showed the most frustration. Provision of sand appeared to reduce ''emotional'' aspects of feed deprivation.