Dhanda O P, Kundu R L
Department of Animal Production Physiology, College of Animal Sciences, CCS Haryana Agricultural University, Hisar 125004, India.
Trop Anim Health Prod. 2001 May;33(3):241-52. doi: 10.1023/a:1010318922445.
Thirty-four 2-year-old ewes, of which 17 were native (Chokla) and 17 were Avivastra (Chokla 67.5% x 32.5% Rambouillet) breeds of similar body weights, were selected. Both groups were maintained under the same management conditions with 8 hours daily grazing. In addition to grazing, each ewe received 300 g/day of a concentrate mixture comprising crude protein 20% and 70% total digestible nutrients. The ewes of both breeds were not mated during the study. The daily environmental parameters were recorded throughout the year, consisting of four main seasons, namely rainy, winter, spring and summer. Blood samples were collected into heparinized tubes during the morning hours for seasonal studies via indwelling jugular vein catheters to avoid stress to the animals, but for the diurnal studies the sampling was done twice daily at 07:00 and 17:00 continuously for three days in each season. Cortisol, thyroxine (T4) and triiodothyronine (T3) were estimated in the samples. The T4 and T3 profiles were maximal in the summer, followed by the rainy season in both groups, with no significant differences. However, the cortisol in both the groups was maximal during the spring rather than the summer. No significant differences were found in T3 concentration between morning and afternoon in any season in the native ewes but these animals showed significantly higher levels of T4 in the morning. The opposite was true for the crossbred animals with regard to both the T3 and T4 profiles. Significantly more cortisol was found in the evening than in the morning in both genetic groups in all seasons.
选取了34只2岁的母羊，其中17只为本地品种（乔克拉），17只为阿维瓦斯特拉品种（乔克拉67.5%×兰布耶32.5%），两组母羊体重相近。两组母羊均在相同的管理条件下饲养，每天放牧8小时。除放牧外，每只母羊每天还会摄入300克由20%粗蛋白和70%总可消化养分组成的精料混合物。在研究期间，两个品种的母羊均未进行配种。全年记录每日环境参数，包括四个主要季节，即雨季、冬季、春季和夏季。为避免对动物造成应激，通过颈静脉留置导管在早晨采集血样用于季节性研究，但在昼夜研究中，每个季节连续三天每天在07:00和17:00各采样一次。对样本中的皮质醇、甲状腺素（T4）和三碘甲状腺原氨酸（T3）进行测定。两组母羊的T4和T3水平在夏季最高，其次是雨季，两组之间无显著差异。然而，两组母羊的皮质醇水平在春季而非夏季最高。本地母羊在任何季节的上午和下午T3浓度均无显著差异，但这些母羊上午的T4水平显著更高。杂种母羊在T3和T4水平方面则相反。在所有季节中，两个品种的母羊晚上的皮质醇含量均显著高于早晨。
