Diet dilution and feeding frequency have only minor effects on the behaviour of broiler breeder pullets

During the rearing period, broiler breeders are feed restricted to prevent the negative impact of fast growth and high body weight on health and reproduction. Feed restriction causes frustration and stress, resulting in stereotypic pecking and hyperactivity. Nutritional strategies have the potential to reduce these welfare issues. Using a 2 x 2 factorial completely randomized block design, pullets were fed with two diet densities and two feeding frequencies during rearing. From 3-23 weeks of age (WOA), pullets received either a standard control diet (CON) or a 16% diluted diet (DIL) containing oat hulls. These diets were provided either once (FO) or twice (FT) a day. After 23 WOA, all pullets received the same standard layer diet once a day. Home pen behaviour was observed by scan sampling at 5, 10, 15, 20, 30 and 39 WOA over eight observation sessions. Furthermore, pullets were subjected to Novel Food Tests (12 and 17 WOA) and Novel Object Tests (5, 10, 15 and 20 WOA). Minor treatment effects were found for foraging and sitting behaviour that varied with age during rearing. Feeding frequency influenced the behavioural patterns of all home pen behaviours (P < 0.001; object pecking P = 0.034), while diet dilution only affected the expression of foraging behaviour during the day (P = 0.007). In all treatment groups, many pullets were observed standing and walking in anticipation of the first meal. After the first meal and before the second meal, more FT pullets were observed standing and walking, while during and after the second meal more FO pullets were observed sitting and performing comfort behaviour. Feeding twice a day resulted in lower daily peaks in drinking behaviour. In the laying period, when all birds received the same layer diet at the same frequency, those who were fed twice daily during rearing foraged more than those who were fed once (P = 0.028) and birds that received a diluted diet during rearing tended to drink more than birds that received the control diet (P = 0.083). Few treatment effects were found in the Novel Food and Novel Object Tests, indicating that diet dilution and/or feeding frequency, as applied here, did not affect fearful behaviour or the motivation to explore. In conclusion, this study showed that neither diet dilution, twice-daily feeding, or the combination of these, improved broiler breeder welfare during rearing and laying. Some changes in the pattern of home pen behaviour were found that indicated a response to the frequency of food provisioning.