Roberts S A, Schaefer A L, Murray A C, Thibault L
School of Dietetics and Human Nutrition, McGill University, Québec, Canada.
Chronobiol Int. 1998 May;15(3):275-81. doi: 10.3109/07420529808998689.
Stress is associated with significant losses in the swine industry. Seasonal changes have been shown to affect stress resistance in several species of animals. In the present study, we examined the effect of two seasons (fall or winter) on plasma insulin, cortisol, and adrenocorticotrophin hormone (ACTH) levels from fasted normal and carrier pigs for stress susceptibility when submitted to a blood-sampling stressor between 10:00 and 11:00. Comparisons were made of 10 diurnally active normal (NN) and 8 carrier (Nn) pigs reared in the fall to 9 NN and 10 Nn pigs reared in the winter. The light-dark cycle throughout the period of the experiment was 10 h light/14 h dark, with lights on from 07:00 to 17:00. Feed consisted of the traditional western Canadian swine ration consumed ad libitum. Results revealed significant season-by-genotype interactions for plasma insulin and ACTH concentrations in response to the blood-sampling stressor. The normal pigs displayed a significantly lower plasma insulin level during winter compared to the fall season. Plasma ACTH of normal pigs was 18% lower in the winter compared to the fall season, although this difference was not statistically significant. The carrier genotype, on the other hand, demonstrated higher plasma insulin concentration and lower plasma ACTH concentration in the winter compared to the fall season. Furthermore, there was a main genotype effect in plasma cortisol concentration such that the carrier pigs experienced a greater level compared to the normal genotype. Similarly, the carrier pigs had a more acute ACTH response to the blood-sampling stressor compared to the normal pigs during the fall season. Results have demonstrated that these two seasons of the year affect the response of both genotypes to a blood-sampling stressor, with the carrier genotype experiencing a more intense stress reaction in the fall season. These results further contribute to the recent research indicating that carrier pigs for stress susceptibility have a unique stress response.
应激与养猪业的重大损失相关。季节性变化已被证明会影响多种动物的抗应激能力。在本研究中，我们检测了两个季节（秋季或冬季）对空腹正常猪和携带应激易感性基因猪血浆胰岛素、皮质醇和促肾上腺皮质激素（ACTH）水平的影响，这些猪在10:00至11:00接受采血应激源刺激。对秋季饲养的10头昼间活动的正常（NN）猪和8头携带基因（Nn）猪与冬季饲养的9头NN猪和10头Nn猪进行了比较。整个实验期间的光照-黑暗周期为10小时光照/14小时黑暗，07:00至17:00开灯。饲料为加拿大西部传统猪日粮，可自由采食。结果显示，针对采血应激源，血浆胰岛素和ACTH浓度存在显著的季节-基因型交互作用。与秋季相比，正常猪在冬季的血浆胰岛素水平显著降低。正常猪冬季的血浆ACTH比秋季低18%，尽管这一差异无统计学意义。另一方面，携带基因的基因型在冬季的血浆胰岛素浓度高于秋季，血浆ACTH浓度低于秋季。此外，血浆皮质醇浓度存在主要的基因型效应，携带基因的猪比正常基因型的猪皮质醇水平更高。同样，在秋季，与正常猪相比，携带基因的猪对采血应激源的ACTH反应更强烈。结果表明，一年中的这两个季节会影响两种基因型对采血应激源的反应，携带基因的基因型在秋季经历更强烈的应激反应。这些结果进一步支持了最近的研究，表明携带应激易感性基因的猪具有独特的应激反应。
