Influence of degree of food restriction, age and time of day on behaviour of broiler breeder chickens.

Six groups of 25 growing female broiler breeder chickens in pens were fed either on a commercial restricted ration (R), twice that amount (2R), or ad libitum (AL). R and 2R birds were fed daily at 09.00 h and ate all their food in < 15 min. Behaviour was observed systematically at three times of day (once before and twice after feeding time) at 6,9,12, 15 and 18 weeks of age. In general, restricted-fed (R and 2R) birds were much more active than AL birds. There were significant (P < 0.05) effects of feeding treatment on all activities recorded except preening and pecking at the empty feeder (R and 2R birds only); age affected drinking, preening, walking, standing and sitting; and time of day affected all activities except feeding (AL birds only). Activities that appeared to reflect feeding motivational state closest were walking before feeding time, and drinking, pecking floor litter and sitting after feeding time. AL birds (only) panted for about a third of the time at moderate ambient temperatures, and changes in their behaviour with age were thermoregulatory. It is proposed that activities of restricted-fed animals that are dominant after feeding time may be substitutable and have common causation and consequences. Distinction between stereotyped and non-stereotyped behaviour in this context may therefore be misleading.