Neighbourhood analysis as an indicator of spatial requirements of broiler chickens
Neighbourhood analysis as an indicator of spatial requirements of broiler chickens
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DOI：
10.1016/j.applanim.2010.11.017
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发表时间：
2011-01-31
影响因子：
2.3
通讯作者：
Tuyttens, Frank A. M.
中科院分区：
文献类型：
--
作者：
Buijs, Stephanie;Keeling, Linda J.;Tuyttens, Frank A. M.
肉鸡的适当饲养密度是动物福利领域讨论较多的话题。为了确定4-6周龄肉仔鸡在什么样的饲养密度下会感到拥挤，对每3.3 m2饲养8、19、29、40、45、51、61或72只鸡的群体的空间分布和行为进行了分析。利用个体间距离、最近邻距离和狄利克雷多边形面积三个指标对空间分布进行评价。假设是，如果高密度（即，与同圈伙伴的密切接近）被认为是令人厌恶的，而如果密切接近被认为是积极的，则它们会减少这种距离。与围栏同伴的距离增加将导致最近邻距离增加和更均匀的分布（即，个体间距离和狄利克雷多边形大小的变化）比预期的机会。通过随机分布和“资源校正”随机分布（其中包括对空间分布的环境影响，但排除社会影响）确定了随机预期的分布。行为观察表明，在较高的放养密度下，发生更多的坐姿发作（P = 0.003）和坐姿和卧姿的调整（P < 0.001）。还发现最近邻距离根据行为而变化（P = 0.001）。吃/喝的鸟比觅食、梳理羽毛、三种空间分析方法的结果均表明，肉鸡群中>= 19只/3.3m2（最终相当于15 kg/m2）在饲养的最后3周的某个时间点开始体验到同种动物的接近是令人厌恶的。然而，最近邻距离分析比其他分析空间分布的方法（个体间距离和多边形大小的变化）更早地显示出厌恶的证据，这表明最近邻距离是空间需求的更敏感指标。对于与资源校正的随机分布的比较）获得了与省略这些测量时不同的结果（即，与随机分布比较）。因此，本研究强调了考虑环境对围栏内分布的影响的重要性。(C)2010 Elsevier B. V.保留所有权利。
The appropriate stocking density for broiler chickens is a much discussed topic in animal welfare. To determine at which stocking density the level of crowding becomes aversive to 4-6-week-old broiler chickens, spatial distribution and behaviour of groups stocked at 8, 19, 29,40, 45, 51, 61 or 72 birds per 3.3 m(2) were analysed. Spatial distribution was evaluated using three different indices: inter-individual distances, nearest neighbour distances and Dirichlet polygon areas. The assumption was that broilers would increase the distance to their pen mates if high densities (i.e., close proximity to pen mates) were experienced as aversive, whereas they would decrease this distance if close proximity was experienced positively. Increased distances to pen mates would lead to increased nearest neighbour distances and a more homogeneous distribution (i.e., lower variation of inter-individual distances and of Dirichlet-polygon size) than expected by chance. The distribution expected by chance was determined from both a random distribution and a 'resource-corrected' random distribution (which incorporated environmental influences on spatial distribution but excluded social ones).Behavioural observations showed that at higher stocking densities more sitting bouts (P = 0.003) and adjustments of the sitting and lying posture (P < 0.001) occurred. It was also found that nearest neighbour distance varied according to behaviour (P = 0.001). Birds that were eating/drinking were further apart from their nearest neighbour than birds that were foraging, preening, adjusting their sitting or lying posture or showing "other" behaviour.The results from all three methods of spatial analysis suggested that broilers in groups >= 19 birds per 3.3 m(2) (ultimately equivalent to 15 kg/m(2)) started to experience the proximity of conspecifics as aversive at some point during the last 3 weeks of rearing. However, nearest neighbour distance analysis showed evidence of aversiveness earlier in life than the other methods of analyzing spatial distribution (variation in inter-individual distance and polygon size), suggesting that nearest neighbour distance is the more sensitive indicator of space requirements.When uneven use of the different areas within the pen was reflected in the expected distribution (i.e., for comparisons to the resource-corrected random distribution) different results were obtained than when such measures were omitted (i.e., for comparisons to the random distribution). As such, this study emphasises the importance of accounting for environmental influences on distribution within a pen. (C) 2010 Elsevier B.V. All rights reserved.