Feeder space affects access to the feeder, aggression, and feed conversion in laying hens in an aviary system

In laying hens, minimal requirements for feeder space (cm per bird) are based primarily on data from small groups of hens (n<10) housed in battery cages. The aim of the present study was to determine the effects of feeder space on agonistic behaviour, access to the feeder, and production in laying hens housed in an aviary system. The experiment was conducted in a quasi-commercial barn that contained 20 pens with 200 Lohmann Selected Leghorn hens housed in each. Five levels of feeder space (3.8, 6.0, 8.0, 9.0, and 10.0cm/hen) were systematically allocated to four pens each from 21 weeks of age onwards. Behavioural assessments from video recordings at 21, 32, 39, and 45 weeks of age included: aggression, jostling followed by either feeding or other behaviour, duration of feeding bouts, and the number of hens feeding from the perch above the feeder as well as simultaneously from the platform at the feeder. Production parameters were measured daily and included: egg production, floor eggs, feed disappearance, and feed conversion ratio. Our results show that more feeder space was associated with less aggression (z-value=−4.06, p<0.001) and less jostling (followed by feeding: z-value=−3.74, p<0.001; followed by other behaviour: z-value=4.24, p<0.001), as well as more simultaneous feeding from the platform at the feeder (z-value=−5.36, p<0.001) and longer feeding bouts (z-value=4.68, p<0.001). Feed disappearance (t-value=3.08, df=18, p=0.006) increased and feed conversion decreased with feeder space (t-value=2.245, df=18, p=0.038). The results indicate positive effects of increased feeder space on laying hen behaviour at the cost of relatively minor production losses. Thus, competition at the feeder decreased with increasing feeder space, allowing more birds to feed simultaneously, while feed conversion decreased only slightly. By combining measures of behaviour and production, our results can facilitate decisions on feeder space for laying hens in view of optimal trade-offs between agonistic behaviour, access to the feeder, and feed conversion.