Laying Hen Welfare: Current Developments in Beak Trimming

蛋鸡福利——禽断喙的发展现状

（颜菲菲，江莎，Hengwei Cheng）

Beak trimming, removal of ¹/₃ to ¹/₂ of the beak, is a routine husbandry procedure practiced in the poultry industry to prevent feather pecking and cannibalism. Domestic chickens possess natural behavior and motivational systems inherited from their ancestors (Red Jungle fowls), such as dust bathing and foraging behavior-associated scratching and ground pecking. Prevention of chickens to perform those behaviors due to living environments results in stress, which leads to express harmful behaviors. Currently, there is no single housing system to meet all chicken’s behavioral and physiological needs. Feather pecking and cannibalism occur in all current housing systems and can lead to suffering and death in laying hens that have not been beak trimmed.

断喙是指去除禽喙的1/3~1/2，是养禽业中的一种常规管理措施，可有效避免禽的啄羽和同类相残。家禽保留了它们祖先（红原鸡）的一些本能行为和动机系统，如沙浴和觅食相关的刨地啄食。若饲养环境限制家禽表现这些行为，可能引起应激，导致异常行为的发生。但是，目前没有一种饲养环境能够完全满足鸡的行为和生理需求。啄羽和同类相残几乎出现在所有饲养模式中，因此，不断喙可致蛋鸡遭受痛苦，甚至死亡。

Issues Related to Beak Trimming

Beak trimming has elicited a great deal of debate and research concerning the relative advantages and disadvantages of the practice from an animal welfare perspective. The bestowed benefits of lowered aggression, feather pecking, and cannibalism may indeed favor improved welfare during the laying cycle. However, a chicken’s beak is a complex, functional organ with an extensive nerve supply. Following beak trimming, several anatomical, physiological, and biochemical changes occur in cut peripheral nerves and damaged tissues. There is a considerable body of morphological, neurophysiological, behavioral and production research demonstrating the emergence of several markers of acute and chronic pain (e.g., persistent lethargy and guarding behaviors, reduced feed intake, and development of neuromas) as a result of trimming. This is of more concern when the beak trimming is conducted in birds which are 5 weeks old or older using a hot-blade beak trimmer.

断喙引起的相关问题

人们从动物福利的角度对断喙引起的利弊进行了大量的讨论和研究。断喙可有效降低蛋鸡的打斗、啄羽和同类相残，有利于改善蛋鸡产蛋期的福利。但是，喙是一个复杂的功能器官，分布有大量的神经末梢。断喙时，周围神经和组织受到损伤，引起了多种解剖、生理和生化变化。大量的体态、神经生理、行为和生产研究表明，断喙引起了急性和慢性疼痛，如持续性的嗜睡和护体行为、采食量减少和神经瘤的发生。尤其值得注意的是对5周龄以上的禽进行热刀断喙时，这些不利影响更为突出。

Hot-Blade Beak Trimming

There are several methods used for beak trimming in the United States but the most popular method is hot-blade beak trimming.  It employs a heated (650-750°C), ‘guillotine’-type, blade that both cuts and cauterizes the beak tissue when birds are 5 to 10 days old. A second beak trimming may be conducted on birds when they are 5 to 8 weeks old if a trimmed beak grows back.

热刀断喙

在美国，断喙有好几种方法，但最常用的是热刀断喙。此方法一般在禽出生后5~10天，用一个加热到650-750℃的刀片切断并烧灼喙组织。如果喙重新生长，禽在5~8周时需进行二次断喙。

Infrared Beak Trimming

Infrared beak treatment is an automated process carried out at the hatchery on 1-day old birds. Birds are immobilized using a head restraint and infrared energy is focused on the area of the beak requiring trimming. High intensity (radiant at 50 to 60 watt) heat penetrates down through the beak’s corneum layer to the corneum-generating basal tissue and inhibits further germ layer growth. After treatment the corneum layer remains intact until 7 to 10 days post-trimming after which the tip of the beak begins to soften and erode away with use.

红外线断喙

红外喙断喙是一个自动化过程，断喙仪通常设置在孵化场，在禽1日龄时即可进行。操作人员将1日龄禽卡在仪器上特质的断喙面罩内，红外能量集中在断喙区域。高强度（50~60瓦）热量通过喙的角质层向下渗透到基底组织并进一步抑制胚芽层生长。刚断喙时角质层保持完整，7~10天后，喙在正常使用过程中尖端开始软化并逐渐脱落。

Recommendation

Infrared beak trimming has several immediate advantages when compared to hot-blade beak trimming: 1) the elimination of open wounds that contribute to bleeding, inflammation, and pain; 2) better adaptation to eating because the changes in beak length and shape occur gradually over a 2-week period, which may better enable birds to alter their beak related behavior, resulting from a progressive adaptation, rather than an instantaneous change in the beak shape; and 3) a reduction in the number of stressors, such as catching, mixing, transfer, and handling, associated with the hot-blade beak trimming when it is performed on birds at 5 to 10 days of age. Long-term observation indicates that infrared beak trimming is more effective at reducing beak re-growth and resulted in less negative effect on feed intake and body weight than hot-blade beak trimming.

Until hens which express very low levels of aggression are commercially available or new housing systems are designed which better meet hens’ behavioral and physiological requirements for minimizing damage imposed by feather pecking and cannibalism, infrared beak trimming is a useful alternative to hot-blade beak trimming. However, the results of beak trimming are affected by multiple factors. It should be noted that the effects of beak trimming on bird well-being is genetic-, lesion- and age-dependent. A future approach for controlling feather pecking and cannibalism in chickens should be the combination of breed, housing design and management practices, which will provide a more promising option for preventing the need for beak trimming.

建议

相比热刀断喙，红外线断喙具有如以下几个明显优势：1）有效避免能导致出血、炎症和疼痛的开放性伤口；2）断喙后采食影响小，红外线断喙引起的喙长度和形状的改变是在大约2周内逐渐发生的，禽类可以更好的适应因断喙引起的改变从而逐步调整相关行为，避免突然改变喙形状导致禽的不适和应激；3）减少应激源，雏禽在5~10天进行热刀断喙时还将经历捕捉、混群和转移等应激源。长期观察研究表明，红外线断喙能更有效地控制喙再生长，对采食量和体重的负影响也小于热刀断喙。

在低攻击性蛋鸡品种被商业化选育或一种全新的可完全满足禽行为和生理需求，并有效控制禽打斗和啄癖的环境友好型商业化饲养环境出现之前，红外线喙断喙是一种有效的副作用更小的可替代热刀断喙的方法。值得注意的是，断喙对禽康乐的影响与基因、疾病和年龄有密切相关。未来控制鸡啄羽和同类相残的有效方法应该是选育品种、改善饲养环境和提高管理方法这三方面的结合，这将会是一个更有可能避免进行禽断喙的途径。

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