Arrazola, A., Mosco, E., Widowski, T. M. et al. 2020. The effect of alternative feeding strategies during rearing on the behaviour of broiler breeder pullets. Applied Animal Behaviour Science 224, 104929.

Broiler breeders are feed-restricted during rearing to avoid the negative consequences of obesity during lay due to their genetic potential for fast growth rate. Feed restriction leads to chronic hunger, frustration and lack of satiety as indicated by hyperactivity, restlessness and oral-redirected behaviours that can become abnormal repetitive behaviours (ARBs). The objective of this study was to examine the effect of a rationed alternative diet and non-daily feeding schedules on the behaviour of broiler breeder pullets under simulated commercial conditions. At 3 weeks of age, 1680 Ross 308 pullets were allocated into 24 pens where they were fed with one of four isocaloric treatments until 22 weeks: 1) daily control diet; 2) daily alternative diet; 3) 4/3 control diet (four on-feed days with three non-consecutive off-feed days per week); and 4) graduated control diet (the feeding frequency varied with age). The alternative diet included a fixed inclusion rate of 40 % soybean hulls and an increasing concentration of 1–5 % calcium propionate. Ten focal pullets per pen (five on on-feed days, five on off-feed days) were continuously observed for 10 min at 7, 10, 14, and 18 weeks of age, starting 30 min after feed delivery. Data were analyzed using mixed linear regression models, with pen nested in the model and age or time of day as a repeated measure. Throughout rearing, pullets on the daily control diet were more active than pullets on the other three treatments (P < 0.001), while pullets on the alternative diet spent more time inactive compared to pullets on the control diet, regardless of feeding schedule (P = 0.02). The percentage of time spent performing ARBs was also lower in pullets fed the alternative diet (1.7 ± 0.8 %) compared to control pullets (26.0 ± 0.8 %; P < 0.001) during early rearing. Pullets on non-daily schedules spent more time in ARBs and locomotion during off-feed days compared to on-feed days (P < 0.05). Our results indicate that a rationed alternative diet can alleviate behavioural signs of chronic hunger, whereas non-daily feed restriction can promote signs of satiety during on-feed days. Compared to daily feed restriction with a control diet, alternative feeding strategies can reduce some of the behavioural signs of feed restriction.