Andersson H, Wallgren M, Rydhmer L, Lundström K, Andersson K, Forsberg M
Centre for Reproductive Biology, Swedish University of Agricultural Sciences, Uppsala.
Anim Reprod Sci. 1998 Dec 31;54(2):121-37. doi: 10.1016/s0378-4320(98)00149-3.
Forty-eight weaned, winter-born crossbred males (average age of 42 days) were exposed to either a natural photoperiod (January-June at 60 degrees N, Control) or one of two artificial photoperiods (1400 lx) in light-sealed rooms. The Spring/Summer group was exposed to an artificial photoperiod simulating conditions from the vernal equinox (mid-March) to August at 60 degrees N and the Autumn/Winter group to a photoperiod, simulating conditions from the autumnal equinox (mid-September) to February at 60 degrees N. Plasma samples were collected biweekly until the pigs were slaughtered, after reaching 115 kg, and analysed for testosterone, estrone sulfate, thyroxine and prolactin. Additionally, three animals per treatment (n = 9) were injected with gonadotropin-releasing hormone (GnRH) and plasma samples were collected every 15 min and analysed for luteinizing hormone and testosterone. Boar taint, carcass composition and reproductive traits were measured at slaughter. Live-weight gain from start to slaughter was lower among the Control animals compared with the Autumn/Winter and Spring/Summer animals. There was a peak in plasma testosterone in both the Spring/Summer and Autumn/Winter groups at 71 days of age, whereas plasma testosterone in the Control group remained at prepubertal levels. At 113 and 127 days of age, the Control group had somewhat higher testosterone levels than the Spring/Summer group, but at 141 days of age and on the day before slaughter, the Autumn/Winter group had a higher mean plasma testosterone concentration. There were no differences between treatments in the endocrine response to the GnRH challenge. Bulbourethral gland weight at slaughter was lower in the Spring/Summer group than in the Autumn/Winter group. The percentage of proximal cytoplasmic droplets was higher in the Spring/Summer group than in both the Control and Autumn/Winter groups. Spermatogenesis at the time of slaughter was clearly more mature in animals in the Autumn/Winter group than in those in the Spring/Summer and Control groups. Fat androstenone was lower in the Spring/Summer group than in the Control group. In the sensory evaluation, the Spring/Summer group had less boar taint than the Autumn/Winter group. Artificial short days with moderate initial changes in photoperiod, stimulated spermatogenesis compared with long days, in accordance with the pattern seen in European Wild Boars (Sus scrofa). Boar taint was also affected with higher scores in the Autumn/Winter group than in the Spring/Summer group, although this was not clearly indicated by the traditional measurements of boar taint-fat contents of androstenone and skatole.
48头断奶的、冬季出生的杂交雄性猪（平均年龄42天）被置于光照密封的房间中，分别接受自然光照周期（北纬60度，1月至6月，对照组）或两种人工光照周期（1400勒克斯）中的一种。春季/夏季组接受模拟北纬60度从春分（3月中旬）到8月条件的人工光照周期，秋季/冬季组接受模拟北纬60度从秋分（9月中旬）到2月条件的光照周期。每两周采集一次血浆样本，直到猪体重达到115公斤被屠宰，然后分析血浆中的睾酮、硫酸雌酮、甲状腺素和催乳素。此外，每组处理选取3头猪（n = 9）注射促性腺激素释放激素（GnRH），每隔15分钟采集一次血浆样本，分析其中的黄体生成素和睾酮。在屠宰时测量公猪异味、胴体组成和繁殖性状。与秋季/冬季组和春季/夏季组相比，对照组猪从开始到屠宰时的体重增加较低。春季/夏季组和秋季/冬季组在71日龄时血浆睾酮均出现峰值，而对照组血浆睾酮水平维持在青春期前水平。在113日龄和127日龄时，对照组睾酮水平略高于春季/夏季组，但在141日龄和屠宰前一天，秋季/冬季组血浆睾酮平均浓度更高。各处理组对GnRH刺激的内分泌反应无差异。春季/夏季组屠宰时尿道球腺重量低于秋季/冬季组。春季/夏季组近端细胞质滴的百分比高于对照组和秋季/冬季组。秋季/冬季组动物屠宰时的精子发生明显比春季/夏季组和对照组更成熟。春季/夏季组脂肪雄烯酮含量低于对照组。在感官评价中，春季/夏季组公猪异味比秋季/冬季组少。与长日照相比，适度初始光照周期变化的人工短日照刺激了精子发生，这与欧洲野猪（Sus scrofa）的模式一致。秋季/冬季组公猪异味得分也高于春季/夏季组，尽管传统的公猪异味测量指标——雄烯酮和粪臭素的脂肪含量并未明确显示这一点。
