Evaluating the use and effectiveness of environmental enrichments in intensive broiler housing
The main aim of this research was to determine whether broiler welfare would be improved by the addition of a dustbathing material to commercial housing. An initial comparison of potential dustbathing materials in Study 1 found an expected preference for peat, however oat hulls also appeared to satisfy broilers motivation to dustbathe and proved considerably more attractive than straw pellets, woodshavings and litter. In Study 2, dust baths of oat hulls were introduced to commercial housing as an alternative or supplementary enrichment to straw bales. Houses containing oat hulls were compared with those containing straw bales, a combination of straw bales and oat hulls, or no enrichment. Although there was no effect of any enrichment condition on house activity levels, there was an improvement in gait score in broilers housed with both oat hulls and a combination of oat hulls and straw bales. Oat hulls were more successful than straw bales at directly stimulating active foraging and dustbathing behaviours, however the bales appeared to provide birds with a valuable resting area and were dismantled throughout the trial. There was also no negative impact of these enrichments on environmental parameters or production levels, including bird body weight. With oat hulls appearing to be a suitable supplementary enrichment, there was interest in knowing how best to present multiple enrichments. Therefore, in Study 3, oat hulls, pecking chain and straw bales were presented singly or arranged into various combinations around a commercial house. The number of broilers attracted to the enrichment areas and the level of engagement with each enrichment type was monitored. There was little effect of grouping enrichments on their level of use, and placing straw bales around oat hulls did not influence the amount of dustbathing and comfort behaviours observed. In fact, there appeared to be practical benefits to distributing enrichments around the house. Study 4 was designed to explore the effects of environmental enrichment on broiler experience and mental well-being. Frequency of stimulated play behaviours and strength of fear responses were compared in houses containing no enrichment, platform perches, and platform perches with peat dust baths. Although no difference in play behaviours was found between treatments, the method of stimulating play described may prove useful in further examining the relevance of these behaviours. Fearfulness appeared to be mitigated in houses containing dust baths, which suggests providing broilers with the opportunity to dustbathe may influence their mental state in commercial housing. This thesis has provided an original contribution to animal welfare research by studying the potential benefits of providing a dustbathing enrichment to commercial broiler chickens, and by describing a novel method of stimulating frolicking and sparring behaviours which may be useful in further understanding play in poultry. This research has also highlighted the need for more commercial scale research for broiler chickens, for example a higher interest in a pecking enrichment was observed in this thesis than has been reported previously. Oat hulls, which are a by-product of oat milling, are suggested as a suitable dustbathing material for broilers in intensive housing. Further research exploring the most efficient ways of presenting and maintaining oat hulls in a commercial house would be useful, and an assessment of their effect on dust levels would be needed to ensure no risk to farm workers.
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