Abstract
The feed restriction applied during rearing of broiler breeders inflicts chronic hunger, and frustration due to unfulfilled behavioural needs for feeding. To alleviate the welfare problems associated with feed restriction, qualitative feed restriction allows a larger amount of feed to be provided without increasing the energy intake. In the present study, the aim was to investigate the effect of scatter-fed qualitative feed restriction on a range of welfare indicators in broiler breeders at the end of the rearing period. In total, 1,200 female breeder chicks of the genotype Ross 308 were housed in 24 pens: six pens of initially 50 birds per dietary treatment. The treatments were: (1) standard feed (Control), (2) standard feed diluted with oat hulls (Insoluble), (3) standard feed diluted with oat hulls and sugar beet pulp (Mixed), and (4) standard feed plus maize silage (Roughage). At 15 weeks of age, a blood sample was taken from 40 birds (10/treatment) five times within 24 h. The plasma was analysed for corticosterone concentration. At 19 weeks of age, a clinical welfare assessment was performed on all birds before they were sacrificed. From each bird, three feathers were plucked and macroscopically examined for the presence of fault bars. Feather length and weight were also recorded. Mortality was registered on occurrence throughout the rearing period. Treatment affected the plumage condition, footpad dermatitis, plumage dirtiness, vent pasting, and number of severe fault bars (P ≤ 0.05) but not plasma corticosterone concentration, hock burns, hyperkeratosis and mortality (P ≥ 0.17). There was an effect of the interactions between treatment and feather type on the total number of fault bars per feather, average position of the fault bars relative to the base of the feather, and growth rates of feather mass and length (P < 0.0001). Overall, the results showed improved welfare of Roughage birds and reduced welfare of Mixed birds, whereas the welfare of Insoluble birds did not seem to differ noticeably from that of Control birds. We recommend to further develop a feeding strategy that includes daily allocation of roughage to broiler breeders during the rearing period.
Highlights
The welfare of conventional broiler breeders has long been debated, limited research has addressed this topic
There was no effect of the interaction between treatment and time of the day on the concentration of plasma corticosterone of the birds [mean ± std. dev: 12.24 ± 5.0 ng/ml; F(12,20) = 1.16; P = 0.37)
Roughage birds tended to have fewer total fault bars in the wing and scapular feathers and had fewer severe fault bars than control birds. These results indicate that roughage birds may experience less stress during the feather growth period than control diet (Control) birds, which is in line with the results of the clinical welfare assessment
Summary
The welfare of conventional broiler breeders has long been debated, limited research has addressed this topic. The consequences of inappropriate diet are hunger, thirst, outbreaks of feather pecking, and diet-related bone problems. Like their offspring, broiler breeders have a great potential for fast growth [2]. Broiler breeders have a great potential for fast growth [2] They are feed restricted throughout life (except for the first week and most severely during the rearing period) to avoid health and reproductive problems arising due to obesity [3, 4]. The feed restriction inflicts chronic hunger and frustration due to unfulfilled behavioural needs for feeding in the broiler breeders [5]
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