A comparison of fast growing broiler chickens with a slower-growing breed type reared on Higher Welfare commercial farms

Abstract

Slowing the growth of modern broiler chickens can have a positive effect on a number of welfare outcomes. However, relatively few studies have compared fast and slower growing broiler chickens reared under the same commercial conditions. The main aim of this study was to evaluate a slower growing breed and standard fast growing broilers on commercial farms. Ross 308 broilers and slower growing Hubbard Redbro broilers were housed on six farms for 17 production cycles. Production data were available for all cycles. Behaviour and environmental measures were taken over one cycle on each of two farms. The farms were visited during weeks 3-6 for both breeds and week 7 for Redbros. We found that breed had a significant effect on a number of measures, including gait score, latency to lie, feather cover, avoidance distances, perch use and play behaviour (p < 0.05). Gait scores were consistently lower among the Redbro flocks during weeks 4, 5, 6 and 7. Redbro broilers generally had longer latency to lie times, better feather cover, and were more reactive to approaching observers. They also showed higher levels of perch use and play. Despite these indications of improved locomotion and physical ability, we found little difference in their general behaviour. However, Redbro broilers did perform longer activity bouts in week 7 than Ross 308s in their final week. There was no effect of breed on dust levels, ammonia concentration or litter condition. Redbro broilers were slaughtered 5.5 days later than Ross 308 birds at a lower average weight (2.32 vs 2.52kg) and had lower mortality, fewer culls and fewer carcasses downgraded at the abattoir. Our results suggest that the slower growing strain was healthier throughout the cycle and more capable of displaying some natural behaviours.

Fig 1. The overall behaviours observed in Redbro and Ross 308 broiler chickens.

Data represent the mean percentage of behaviours over observation periods in week 3–6 of the production cycle. Foraging and Other were infrequently seen and were excluded from analysis.

Fig 2. The overall behaviours observed in Redbro and Ross 308 broiler chickens, by week.

Mean percentage of behaviours observed in Redbro and Ross 308 broiler chickens, by week. Foraging and Other were infrequently seen and excluded from analysis. Week 3–6 of the production cycle consists of both Redbro and Ross 308 data, and week 7 consisted of only Redbro behaviour data.

Fig 3. Perch occupancy results for Redbro and Ross 308 broiler chickens.

Mean number of broilers on top of the platform perch, by week and breed. Different letters denote significant difference (p < 0.05) between weeks for Redbro broilers, following simple effects post-hoc analysis. * denotes a significance between 7 week old Redbro broilers and 6 week old Ross 308 broilers.

Fig 4. The response of broiler chickens to novel objects over the production cycle.

The number of birds that pecked at the novel object during the test, and the number of birds within a 50 cm diameter of the novel object are presented. Different letters denote significant differences (p < 0.05) between the weeks within each test, for weeks 3–6 of the production cycle.

Fig 5. The distribution of causes of carcass downgrades for Redbro broilers and Ross 308 broilers at slaughter.

* denotes a significant difference between breed in the % of broilers given that downgrade category.