Archer G S, Mench J A
Department of Animal Science and Center for Animal Welfare, University of California-Davis, One Shields Ave, Davis 95616.
J Anim Sci. 2014 Apr;92(4):1753-8. doi: 10.2527/jas.2013-7129. Epub 2014 Feb 10.
Light stimulation during incubation can affect the behavior, health, and performance of poultry posthatch. However, there has been relatively little work systematically assessing the pattern of light stimulation needed to produce these effects or the mechanism underlying them. We conducted 2 experiments to assess the effects of duration and onset of light exposure during incubation on Cobb 500 broiler chickens. In the first, eggs (n = 1,404) were incubated under photoperiods of either 0 h of light and 24 h of darkness (0 L:24 D), 1 h of light and 23 h of darkness (1 L:23 D), 6 h of light and 18 h of darkness (6L:18D), or 12 h of light and 12 h of darkness (12L:12D). In the second, eggs (n = 1,008) were incubated in either complete darkness or under 12L:12D, which was applied either for the entire incubation period or with light onset beginning at either 7 or 14 d of incubation. Broilers were then housed in floor pens under a 12L:12D cycle posthatch. Measurements included performance outcomes, plasma melatonin, general behavioral activity assessed using passive infrared detection, and feeding activity assessed using automated continuous monitoring of feed intake at wk 5 of age. There were no treatment differences in hatchability, mortality, growth, feed consumption, feed conversion ratio, overall feeding behavior activity, or general behavioral activity over a 24-h period in either experiment. However, broilers incubated under 12L:12D fed more (P < 0.05) than the 0 L:24 D broilers during the first 3 h after the lights came on in Exp. 1 and during the first hour after the lights came on in Exp. 2. In Exp. 1, general activity levels measured using passive infrared detection at night also differed (P = 0.05), with 0 L:24 D more active than 12L:12D. There was a treatment difference between the 0 L:12 D and 12 L:12 D in their plasma melatonin rhythms during d 19 of incubation, but this difference had disappeared when broilers were sampled at wk 5 posthatch. The results of this study indicate that providing 12 h of light during incubation can have a long-lasting effect on the diurnal rhythms of behavior, although the mechanism underlying this does not appear to be related to a persistent change in melatonin rhythm.
孵化期间的光照刺激会影响雏禽出壳后的行为、健康和生产性能。然而，系统评估产生这些影响所需的光照刺激模式或其潜在机制的研究相对较少。我们进行了两项实验，以评估孵化期间光照时长和光照开始时间对科宝500肉鸡的影响。在第一个实验中，将鸡蛋（n = 1,404）分别置于光照0小时、黑暗24小时（0L:24D）、光照1小时、黑暗23小时（1L:23D）、光照6小时、黑暗18小时（6L:18D）或光照12小时、黑暗12小时（12L:12D）的光周期下孵化。在第二个实验中，将鸡蛋（n = 1,008）分别置于完全黑暗环境中或12L:12D光周期下孵化，12L:12D光周期要么应用于整个孵化期，要么在孵化第7天或第14天开始光照。雏鸡出壳后饲养在地面围栏中，采用12L:12D的光照周期。测量指标包括生产性能指标、血浆褪黑素、使用被动红外检测评估的一般行为活动，以及在5周龄时通过自动连续监测采食量评估的采食活动。在这两项实验中，孵化率、死亡率、生长、采食量、饲料转化率、24小时内的总体采食行为活动或一般行为活动在各处理间均无差异。然而，在实验1中，光照开启后的前3小时以及实验2中光照开启后的第1小时，在12L:12D光周期下孵化的肉鸡采食量比0L:24D光周期下孵化的肉鸡更多（P < 0.05）。在实验1中，夜间使用被动红外检测测量的一般活动水平也存在差异（P = 0.05），0L:24D光周期下的肉鸡比12L:12D光周期下的肉鸡更活跃。在孵化第19天，0L:12D和12L:12D处理的肉鸡血浆褪黑素节律存在差异，但在出壳后5周采样时，这种差异已消失。本研究结果表明，孵化期间提供12小时光照可对行为的昼夜节律产生长期影响，尽管其潜在机制似乎与褪黑素节律的持续变化无关。
