Pelletier J, Thimonier J
Laboratoire de Physiologie de la Reproduction, INRA, Nouzilly, France.
J Reprod Fertil. 1987 Sep;81(1):181-6. doi: 10.1530/jrf.0.0810181.
Two groups of 12 adult Ile-de-France rams were exposed to artificial 6-month light cycles in which daily illumination was provided in one or two photofractions. In Group I, daylength increased linearly from 8 to 16 h in 3 months and decreased similarly from 16 to 8 h. The daily increment or decrement (5.33 min/day) was constant. In Group II, 8 h of light were given in two parts: the main one, 7 h, began at the time of dawn in Group I and an additional 1 h light pulse was coincident with the last hour of the former group. The onset of the pulse changed therefore each day and the interval between dawn of the first block and dusk of the second block of light increased from 8 to 16 h in 3 months and declined from 16 to 8 h the next 3 months. Testicular weight was estimated by an orchidometer every 2 weeks for 2 (N = 12/group) or 3 consecutive light cycles (N = 6/group). The testicular weight variations were identical in both groups. In the 6 rams of each group studied during 3 light cycles, variations of testicular weight were submitted to an harmonic regression analysis according to time and the computed values for the mean, amplitude, period and phase were, respectively, 260 g, 66 g, 185 days and 120 days in Group I and 262 g, 65 g, 181 days and 111 days in Group II. Analysis performed for each ram gave very similar values in all individuals.(ABSTRACT TRUNCATED AT 250 WORDS)
两组各12只成年法兰西岛公羊被置于为期6个月的人工光照周期中，每日光照分为1或2个光段。在第一组中，日长在3个月内从8小时线性增加到16小时，然后以类似方式从16小时减少到8小时。每日增减量（5.33分钟/天）保持恒定。在第二组中，8小时光照分为两部分：主要部分为7小时，从第一组黎明时开始，额外的1小时光脉冲与前一组的最后1小时重合。因此，脉冲的开始时间每天都在变化，第一个光照时段的黎明到第二个光照时段的黄昏之间的间隔在3个月内从8小时增加到16小时，接下来的3个月从16小时减少到8小时。每2周用睾丸测量器估计一次睾丸重量，持续2个（每组N = 12）或3个连续光照周期（每组N = 6）。两组的睾丸重量变化相同。在每组研究的3个光照周期的6只公羊中，根据时间对睾丸重量变化进行谐波回归分析，第一组计算出的平均值、振幅、周期和相位值分别为260克、66克、185天和120天，第二组分别为262克、65克、181天和111天。对每只公羊进行的分析在所有个体中给出了非常相似的值。（摘要截断于250字）
