笼底类型对肉仔鸡行为的影响及其与胸囊肿发生率的关系

为研究笼养肉仔鸡胸囊肿发生的行为学机制,观察比较3种盒式笼(笼底分别由铁丝网、塑料片和竹竿组成)中肉仔鸡从3至6周龄的行为,以及胸囊肿发生率的差异。结果表明6周龄时,肉仔鸡在3种笼底上的伏卧行为虽无显著差异,但在行为格局中其比例最高(均在70%以上),而站立、行走和晃动3种行为之和仅占10%左右;竹竿笼底上的肉仔鸡行走频次、晃动频次和比例均显著高于铁丝和塑料笼底上的(均P<0.05),而竹竿笼底上的肉仔鸡胸囊肿发生率显著低于铁丝笼底上的(P<0.05);随着周龄增长,铁丝笼中肉仔鸡行走和晃动频次均减少,伏卧时间延长,胸骨承受的重量增大,这增加了胸部与铁丝网笼底接触及摩擦的几率和时间。实验结果说明,笼养肉仔鸡行为格局趋向静态单一化(动态行为频次降低,静态行为比例占优势)与其胸囊肿发病率的变化相一致,提示两者存在某种内在联系。这验证了我们提出的假设,即依赖于笼底类型和周龄的肉仔鸡行为趋向静态性是胸囊肿形成的必经环节。

Effects of Cage Floor Systems on Behaviours and Breast Blister in Battery Broilers

In order to investigate the relationships between cage floor systems, behaviours and breast blisters in broiler chickens, we observed behavioural patterns and the incidence of breast blisters in chickens housed in three types of cages with different floors from the age of three weeks to six weeks. At three-four weeks, there were no occurrences of breast blisters among the broilers in all types of cages. At five and six weeks, there was a breast blister incidence of 14.75% and 20.68% respectively in broilers housed in wire-floored-cages. In plastic-floored cages, there was a 1.69% incidence of breast blister at both five and six weeks of age and in bamboo-floored cages an incidence of 0.76% at both ages. This presents a significant difference in breast blister incidence between wire floor-caged broilers and plastic/bamboo floor-caged broilers (P<0.05). Although there was no significant difference in lying behaviour of broilers in the three types of cages, lying was the most common behavioral pattern of broilers in all three types of cages at over 70% at the age of six weeks. Meanwhile, broilers in bamboo-floored cages displayed significantly higher frequency of walking and shaking than did broilers in wire/plastic-floored cages (all P<0.05). In wire-floored cages, walking and shaking frequency reduced notably with age, while the duration of lying and the weight on the sternum both increased. This results in the breast frequently touching and rubbing the wire floor accounting for the prevalence of breast blisters. These results suggest that the association of behavioural patterns with the type of cage floor and the prevalence of lying behaviour are key issues influencing the occurrence of breast blisters in battery broilers.