Density allowances for broilers: Where to set the limits?
Density allowances for broilers: Where to set the limits?
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DOI：
10.1093/ps/86.6.1265
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发表时间：
2007-06-01
期刊：
影响因子：
4.4
通讯作者：
Estevez, I.
中科院分区：
文献类型：
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作者：
Estevez, I.
饲养密度对肉鸡行业具有至关重要的影响，因为随着单位空间内鸡只数量的增加可以获得更高的回报。指定的密度主要是由成本效益分析驱动的，但如果密度过高，经济利润可能会以降低鸡只的性能、健康和福利为代价。这些负面后果是人们越来越需要限制密度津贴的指导方针（甚至通过立法）的主要原因。目前推荐的密度变化很大，因此，如果要制定基于可靠科学的指南，这一点至关重要。已发表的研究一致表明，如果空间限额降至每只鸡 0.0625 至 0.07 m(2) 以下（相当于约 34 至 38 kg/m(2)，具体取决于最终体重），肉鸡的健康和福利就会受到损害。负面后果包括最终体重、采食量和食物转化率降低，以及足垫皮炎、抓伤、瘀伤、羽毛质量较差和谴责的发生率增加。一些研究还发现死亡率较高、胫骨软骨发育不全以及一些生理应激的证据。在行为层面，大多数研究表明空间使用和运动的减少以及干扰频率的增加，这与划伤频率的增加和胴体质量的下降有关。其他主要行为类别基本保持不变。然而，结果绝大多数表明，虽然饲养密度对肉鸡的健康和福利有重大影响，但很大程度上被低估的环境质量的影响要大得多。除非制定一些环境质量标准，否则肉鸡福利的进步将很难实现。这意味着，只要满足环境质量的要求，肉鸡的福利就可以在一定的（合理的）密度范围内得到保证。行业还必须认识到，如果密度过高，肉鸡生产中单位空间的回报确实会趋于稳定，这是导致鸡只生产性能下降的结果。在本文中，我提出了一个可用于最大化生产力、健康和福利的模型。
Stocking density has critical implications for the broiler industry because higher returns can be obtained as the number of birds per unit space increases. Assigned densities have been primarily driven by cost-benefit analysis, but economic profit may come at the cost of reduced bird performance, health, and welfare if densities are excessive. These negative consequences are the primary reason for the increasing demands for guidelines that limit density allowances, even through legislation. Current recommended densities are rather variable, and therefore it is critical if guidelines are to be established that they be based on sound science. Published research consistently indicates that the health and welfare of broilers is compromised if space allowances drop below 0.0625 to 0.07 m(2)/ bird (equivalent to about 34 to 38 kg/ m(2) depending on final BW). Negative consequences include reduced final BW, feed intake and food conversion, and greater incidence of foot-pad dermatitis, scratches, bruising, poorer feathering, and condemnations. A few studies have also found higher mortalities, tibial dischondroplasia, and some evidence of physiological stress. At the behavioral level, most studies indicate a reduction in space use and movement and higher frequencies of disturbances, which has been linked with a higher frequency of scratches and decline in carcass quality. Other main behavioral categories remain largely unchanged. However, results overwhelmingly suggest that while stocking density has major consequences for the health and welfare of broilers, the quality of the environment, which has been largely underestimated, is far more relevant. Advances in broiler welfare will be difficult to achieve unless some criteria for environmental quality are also established. The implications of this are that the welfare of broilers can be ensured at a range of (reasonable) densities, as long as the requirements for environmental quality are fulfilled. It is also essential for industry to realize that returns per unit of space in broiler production do tend to plateau if density is excessive, a result of the reduction in bird performance. In this paper I suggest a model that may be used to maximize productivity, health, and welfare.