Motivation for feeding in broiler breeder pullets fed different types of restricted high-fibre diets

High-fibre diets have been suggested as alternative feeding strategies that potentially may alleviate the hunger felt by feed-restricted broiler breeders and fulfil their behavioural need for feeding behaviour. The aim of the present study was to investigate the effects of four dietary treatments, differing in fibre types and content, on the motivation for performing feeding behaviour, including both the appetitive and consummatory phase, in broiler breeder pullets. In total, 1200 female breeder chicks of the genotype Ross 308 were housed in 24 pens, six pens of initially 50 birds per treatment. The dietary treatments were: 1) standard feed (Control), 2) feed containing insoluble fibres (Insoluble), 3) feed containing a mix of insoluble and soluble fibres (Mixed) and 4) standard feed supplemented with maize silage (Roughage). Four measures of feeding motivation were obtained: feeding rate, behaviour indicating frustration during thwarted feeding, compensatory feed intake over 5 days and motivation to gain access to fresh litter. The latter was performed at 12-13 weeks of age, whereas the other measures were obtained both at 8-9 and 17-18 weeks of age. Litter quality in the home pens was assessed at age 13 weeks and dry matter content at 5, 13 and 14 weeks of age. Feeding rate was not affected by treatment (P = 0.26). Insoluble and Mixed birds showed fewer behavioural transitions, i.e. changes in activity, during thwarted feeding at 17/18 weeks of age than Control birds (P = 0.004), indicating less frustration and thus a lower feeding motivation. The compensatory feed intake was lower for Insoluble birds compared to Control birds, indicating that the Insoluble treatment reduced the hunger experienced by the birds. Mixed birds were clearly more motivated to gain access to the fresh litter with more and faster crossings into the litter compartment (P <= 0.01). Although foraging was the predominant behaviour performed in the litter compartment, Mixed birds spent less time on locomotion (P = 0.002), more time on comfort behaviour (P = 0.02) and more time resting (P < 0.0001) than Control birds, suggesting that they were also motivated to gain access to litter for increased comfort. The litter quality in the home pens was poorest in the Mixed treatment (P = 0.0001). In conclusion, none of the treatment diets seemed to improve the welfare of broiler breeders markedly during the rearing period, although the Mixed and Insoluble diets may, to some extent, have reduced the feeding motivation.