Effect of Environmental Enrichment on the Body Weight in Broiler Chickens

ABSTRACT The present study had the objective of analysing the impact of the use of environmental enrichment (music and light stimuli), broiler sex, and age in broiler chickens’ weight during growth. The observational study was carried out on a commercial farm. The environmental enrichment consisted of broilers’ stimulation by sound and light, and a house was kept without stimulus (control). The music stimuli consisted of different music styles and was played during the experiment to promote motivation for the birds. The light stimuli came from a coloured (red and green) LED strobe projector. Both stimuli were applied once a day for about 6 minutes, for five weeks. The broilers were weighed at the end of each week of growth. Throughout the growth period, broiler behaviours were analysed weekly through videos, and the leg disorders of the birds were put into score evaluations. The effects of the environmental enrichment type, gender, and age, and the probable interactions of these variables, on the weight of the broiler chickens were analysed by the comparative analysis of means, analysis of variance (ANOVA), and Tukey test of multiple comparisons. 7, 14, and 21 day old broiler chickens did not differ on body weight when compared with age, gender, and environmental enrichment (broiler house) (p>0.05). Males from 21 days of age had an increase in body weight when compared with females. Light enrichment presented the lowest body weight when compared with all studied houses, while the absence of enrichment presented the highest broiler weight.摘要 本研究旨在分析环境丰容（environmental enrichment，包含声音与光刺激）、肉仔鸡性别以及日龄对生长阶段肉仔鸡体重的影响。本观察性研究于一处商业养殖场开展。环境丰容方案包含对肉仔鸡施加声音与光刺激，同时设置无刺激的饲养舍作为对照组。声音刺激采用多种风格的音乐，在实验期间持续播放以提升肉仔鸡的活动意愿；光刺激则通过红绿双色LED频闪投影仪施加。两种刺激均每日施加一次，每次持续约6分钟，实验周期为5周。研究人员于生长周期的每周末对肉仔鸡进行体重称量，并在整个生长阶段每周通过录像分析肉仔鸡的行为表现，同时对肉仔鸡的腿部病症开展评分定级。本研究通过均值比较分析、方差分析（ANOVA）以及图基多重比较检验，分析了环境丰容类型、性别、日龄及其变量间潜在交互作用对肉仔鸡体重的影响。结果显示，在日龄、性别与环境丰容（饲养舍）的影响下，7、14和21日龄的肉仔鸡体重无显著差异（p>0.05）；21日龄及之后的雄性肉仔鸡体重显著高于雌性肉仔鸡。相较于所有受试饲养舍，施加光刺激丰容的饲养舍中肉仔鸡体重最低，而无丰容刺激的饲养舍肉仔鸡体重最高。