Classen H L, Riddell C
Department of Animal and Poultry Science, University of Saskatchewan, Saskatoon, Canada.
Poult Sci. 1989 Jul;68(7):873-9. doi: 10.3382/ps.0680873.
Three experiments were conducted to examine the impact of changing photoperiod length on the performance of chicken broilers. Effect of long, constant (23-h) photoperiod length (23H) was compared with treatments where photoperiod increased from 6 to 23 h abruptly after 21 days (6H) or gradually during the experiment (INC). The 6H program was used in all three experiments, whereas the INC treatment was included only in Experiment 3. Differences between total body weight gains of birds in the 6H and 23H treatments were inconsistent and small in the three experiments. In Experiment 3, there were no differences between total body weight gains for INC, 6H, and 23H treatments. Feed-to-gain ratios for 6H broilers were significantly superior to those for birds on the 23H treatment for Days 0 to 21 (all experiments), Days 21 to 42 and Days 0 to 42 (Experiment 2), and inferior for Days 21 to 42 (Experiment 3). The INC treatment was significantly superior to the 23H program for all time periods and to 6H birds for Days 21 to 42 and Days 0 to 42. The 6H treatment significantly reduced the incidence of leg abnormalities in comparison with the 23H program in all experiments; the INC and 6H treatments were equal in incidence in Experiment 3. When data from the three experiments were combined, mortality due to sudden death syndrome and other causes for the 6H treatment was significantly lower than that of the 23H program; values for the 6H and INC treatments were not different in Experiment 3.(ABSTRACT TRUNCATED AT 250 WORDS)
进行了三项实验，以研究光照周期长度变化对肉鸡生长性能的影响。将长的、恒定（23小时）的光照周期长度（23H）的效果与光照周期在21天后从6小时突然增加到23小时（6H）或在实验期间逐渐增加（INC）的处理进行比较。在所有三项实验中都采用了6H方案，而INC处理仅包含在实验3中。在这三项实验中，6H和23H处理的鸡的总体重增加之间的差异不一致且较小。在实验3中，INC、6H和23H处理的总体重增加之间没有差异。在第0至21天（所有实验）、第21至42天和第0至42天（实验2），6H肉鸡的料重比显著优于23H处理的鸡，而在第21至42天（实验3）则较差。在所有时间段，INC处理显著优于23H方案，在第21至42天和第0至42天优于6H鸡。与所有实验中的23H方案相比，6H处理显著降低了腿部异常的发生率；在实验3中，INC和6H处理的发生率相同。当将三项实验的数据合并时，6H处理因猝死综合征和其他原因导致的死亡率显著低于23H方案；在实验3中，6H和INC处理的值没有差异。（摘要截断于250字）
