Age, lighting treatment, feed allocation and feed form influence broiler breeder feeding time
During a broiler breeder trial with 3200 Cobb 500 hens, the effects of lighting treatment after 20 weeks’ feed allocation and of feed form on the length of time taken to consume the daily allocation of feed were measured. Pullets were reared on 8-hour photoperiods to 20 weeks, then transferred to one of four lighting treatments: permanently to 11 h or 16 hours, transferred temporarily to 11 hours, then given 2-hours increments at 40, 44 and 48 weeks to reach 17 hours or a commercially recommended step-up lighting programme (11 hours at 20 weeks, incrementing by 30 min per week to reach 16 h by 30 weeks). Feed was made available in mash or pelleted form, and hens received 160 g or 180 g by 30 weeks. This allocation was increased linearly from 100 g at 20 weeks. After 40 weeks, the daily feed allocation was reduced by 5 g/bird for each 5% reduction in rate of lay to a minimum of 150 or 160 g/bird. On five occasions, when the hens were 39, 40, 41, 45 and 54 weeks old, the time taken by the hens to consume all their feed was measured and scaled to min/100 g consumed. Hens learned to consume the feed more rapidly as the laying period progressed. The mean clean-up time over all treatments was 67.7, 62.1, 63.4, 47.1 and 40.2 min/100 g at the five ages. Over all treatments and ages, the time taken to consume all their feed was 40.0 min/100 g for birds fed 160 g, versus 72.2 min for those given 180 g of food daily, but this difference was greater at 39 weeks (43.5 versus 91.8) than at 54 weeks (34.0 versus 46.4 min/100 g, respectively). This effect was also evident with feed form, the difference in time taken to consume mash and pellets being greater at 39 weeks (69.2 versus 66.1) than at 54 weeks (54.7 versus 25.7 min/100 g, respectively). The lighting programmes also had an effect on the feed clean-up time. The main effects were 53.5, 56.3, 52.1 and 62.5 min/100 g for the 11-hour constant, 11 to 16 hours, 16-hour constant and step-up programmes, respectively. Significant interactions occurred between treatments. The main reason was the much longer time taken initially by birds receiving the step-up lighting programme and 180 g of pelleted feed to consume all their feed. The effects of these treatments on bird welfare are discussed.
Keywords: Breeders, laying period, lipid reserves, welfare