Evans N M, Hacker R R
Department of Animal and Poultry Science, University of Guelph, Ontario, Canada.
J Dairy Sci. 1989 Nov;72(11):2921-7. doi: 10.3168/jds.S0022-0302(89)79443-1.
The objective of this study was to determine if chronobiological manipulation of the environment through the use of skeletal photoperiods could enhance milk production of the dairy cow. Cows in their 8th mo of gestation were maintained in either a control light regimen (12 to 13 h continuous light) or three skeletal photoperiods exposed to a total of 8 h of light. Cows in the skeletal photoperiods received 6 h of light from 0500 to 1100 h and a 2 h light pulse between 1500 and 1700 h (pulse 1500 to 1700 h), 1800 and 2000 h (pulse 1800 to 2000 h), or 2100 and 2300 h (pulse 2100 to 2300 h). Cows were milked twice daily and milk weights recorded. Weekly milk samples were analyzed for fat, protein, lactose, and SCC. Milk progesterone was monitored for the first 60 d after calving to determine return to estrus. Total electrical consumption for lighting the different light regimens were monitored throughout the lactation. Cows in the light regimen of pulse 1800 to 2000 h exhibited a higher persistency of lactation and a higher feed efficiency than the cows in the other light regimens. There were no differences between treatments in milk fat, protein, lactose, or SCC. The total electricity used to light pulse 1800 to 2000 h was 50% less than that used to light the control light regimen. It is concluded that light is essential between 13 to 15 h after subjective dawn for increasing persistency of lactation. Further, milk production of the dairy cow can be profitably enhanced through the use of chronobiological principles.
本研究的目的是确定通过使用骨骼光周期对环境进行生物钟调控是否能够提高奶牛的产奶量。处于妊娠第8个月的奶牛被饲养在要么是对照光照方案（12至13小时持续光照），要么是三种骨骼光周期方案下，总光照时长为8小时。处于骨骼光周期方案下的奶牛在0500至1100小时接受6小时光照，并在1500至1700小时（脉冲1500至1700小时）、1800至2000小时（脉冲1800至2000小时）或2100至2300小时（脉冲2100至2300小时）之间接受2小时的光脉冲。奶牛每天挤奶两次并记录产奶量。每周采集的牛奶样本用于分析脂肪、蛋白质、乳糖和体细胞数。在产犊后的前60天监测牛奶孕酮水平以确定发情恢复情况。在整个泌乳期监测不同光照方案的总耗电量。处于脉冲1800至2000小时光照方案下的奶牛比其他光照方案下的奶牛表现出更高的泌乳持续性和更高的饲料效率。各处理组之间在牛奶脂肪、蛋白质、乳糖或体细胞数方面没有差异。用于脉冲1800至2000小时光照的总电量比用于对照光照方案的电量少50%。得出的结论是，在主观黎明后13至15小时之间的光照对于提高泌乳持续性至关重要。此外，通过应用生物钟学原理可以有利可图地提高奶牛的产奶量。
