Natural incubation patterns and the effects of exposing eggs to light at various times during incubation on post-hatch fear and stress responses in broiler (meat) chickens
Natural incubation patterns and the effects of exposing eggs to light at various times during incubation on post-hatch fear and stress responses in broiler (meat) chickens
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DOI：
10.1016/j.applanim.2013.12.010
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发表时间：
2014-03-01
影响因子：
2.3
通讯作者：
Mench, Joy A.
中科院分区：
文献类型：
--
作者：
Archer, Gregory S.;Mench, Joy A.
虽然孵化期间的环境条件会影响家禽的福利，但在鸡蛋的商业孵化中经常被忽视的一个因素是光。目前已知胚胎发育期间的光刺激会影响肉鸡孵化后的生理和行为，但对产生这些影响所需的暴露模式知之甚少。为了确定自然孵化的鸡蛋暴露在光线下的频率，我们给了10只正在孵蛋的原灰鹰x新罕布夏红母鸡一个装有5枚可受精鸡蛋的巢箱和一个光敏数据记录仪，该记录仪通过确定光线是否到达鸡蛋来记录出勤情况。在21天的孵化周期中，母鸡平均有14.3天呆在窝里不离开，尽管它们确实会定期离开，特别是在最后一周。利用这些信息，我们随后研究了孵育期间光照时间如何影响肉鸡孵化后的恐惧和应激反应。卵要么不暴露在光照下（ODL），要么在整个孵育过程中（21 DL）暴露在光照下，要么只在孵育的最后2周（14DL）或最后一周（7DL）暴露在光照下。光照模式对所有测量参数都有显著影响，在ODL和21 DL之间发现了最一致的差异。在恐惧测试中，ODL鸟在紧急测试中有更长的出现延迟（62.7比37.2秒），在强直静止测试中有更长的向右延迟（223.8比107.2秒），在翻转测试中翅膀拍动更强烈（7.03比6.4拍动/秒），在隔离测试中发声更多（172.7比127.1/3分钟）。与21 DL相比，ODL对应激源的IgG滴度较低（52,683比97,375单位），皮质酮反应较强（1.18比0.55 ng/mL），并表现出更多的复合不对称（1.96比1.49 mm）。14DL和7DL组一般处于中间水平。与暗孵育的雏鸡不同，所有光刺激组在羽化试验中都表现出逃跑方向偏侧化，这表明光诱导的大脑偏侧性可能在观察到的效应中起作用。然而，侧化的方向取决于曝光的时间。这些结果证实了孵育期间光刺激对肉鸡后期行为和生理的重要性，但也表明，仅在孵育的最后一周提供光，这与母鸡离开巢所提供的最大光刺激相吻合，不足以产生这些影响。(C) 2014 Elsevier B.V.版权所有
Although environmental conditions during incubation can affect poultry welfare, one factor often overlooked in the commercial incubation of eggs is light. Light stimulation during embryonic development is now known to affect the physiology and behavior of broiler (meat) chickens post-hatch, but little is known about the pattern of exposure needed to produce these effects. We determined how often naturally incubated eggs were exposed to light by giving 10 broody Junglefowl x New Hampshire Red hens a nestbox containing five fertile eggs and a light sensitive data logger which recorded nest attendance by determining whether light was reaching the eggs. On average hens stayed on the nest without leaving for 14.3 of the days of the 21-day incubation cycle, although they did leave periodically, particularly during the last week. Utilizing this information, we then investigated how the timing of light exposure during incubation affected fear and stress responsiveness post-hatch in broiler chickens. Eggs were either not exposed to light (ODL), or exposed to light throughout incubation (21 DL) or during only either the last 2 weeks (14DL) or the last week (7DL) of incubation. Lighting pattern had a significant effect on all parameters measured, with the most consistent differences found between ODL and 21 DL. For the fear measures, the ODL birds had a longer latency to emerge during an emergence test (62.7 versus 37.2 s), a longer latency to right during a tonic immobility test (223.8 versus 107.2 s), wing-flapped more intensely during an inversion test (7.03 versus 6.4 flaps/s), and vocalized more during an isolation test (172.7 versus 127.1/3 min) than the 21 DL For the stress measures, ODL had a lower IgG titer (52,683 versus 97,375 units) and greater corticosterone response (1.18 versus 0.55 ng/mL) to the crating stressor than 21 DL, and showed more composite asymmetry (1.96 versus 1.49 mm). The 14DL and 7DL groups were generally intermediate. Unlike dark-incubated chicks, all light-stimulated groups showed lateralization of escape direction during the emergence test, suggesting that light-induced cerebral laterality could play a role in the observed effects. However, the direction of lateralization differed depending upon timing of exposure. These results confirm the importance of light stimulation during incubation on the later behavior and physiology of broiler chickens, but also indicate that providing light only during the last week of incubation, which would coincide with the maximum light stimulation provided by hens' excursions from the nest, is insufficient to produce these effects. (C) 2014 Elsevier B.V. All rights reserved.