ABSTRACT Cortisol hormone shows distinct circadian rhythmicity in humans and animals. In this study, preliminary cortisol assessments were conducted using wool samples from ewes (nine ewes) exploiting both RIA and ELISA assays. Afterwards, eighteen high production (milk = 38 ± 1.5 kg d−1) lactating Holstein cows (2nd parity) and 12 growing heifers (10–12 mo of age, BW = 200 ± 35 kg) were employed in this experiment. Higher (P = 0.04) serum cortisol and subsequently significantly higher (P = 0.001) hair cortisol levels were observed in lactating cows compared with heifers. Both RIA and ELISA (intra- and inter-assay coefficients of variations were 1.11 and 10.61, respectively) assays were used and the accuracy was approximately 0.0031 µg/dL similar to the wool cortisol assessment. Apart from the limitations of using RIA assay, using ELISA for the hair/wool cortisol analysis provided more reliable data output and less errors. In addition, application of ELISA is more environmental-friendly. Lower cortisol values were observed in both hair and plasma of Holstein heifers than those of lactating cows concluding that lactating cows are more vulnerable to thermal stress than growing heifers.

中文翻译：

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使用 RIA 和 ELISA 测定法测量绵羊和奶牛的毛发和血液皮质醇：比较

摘要皮质醇激素在人类和动物中显示出明显的昼夜节律性。在这项研究中，使用来自母羊（9 只母羊）的羊毛样本，利用 RIA 和 ELISA 测定法进行了初步皮质醇评估。之后，在该实验中使用了 18 头高产（牛奶 = 38 ± 1.5 kg d-1）泌乳荷斯坦奶牛（第 2 胎）和 12 头生长中的小母牛（10-12 月龄，体重 = 200 ± 35 kg）。与小母牛相比，泌乳母牛的血清皮质醇水平更高（P = 0.04），随后显着更高（P = 0.001）的毛发皮质醇水平。使用 RIA 和 ELISA（测定内和测定间变异系数分别为 1.11 和 10.61）测定，准确度约为 0.0031 µg/dL，类似于羊毛皮质醇评估。除了使用 RIA 检测的局限性外，使用 ELISA 进行毛发/羊毛皮质醇分析提供了更可靠的数据输出和更少的错误。此外，ELISA的应用更加环保。在荷斯坦小母牛的毛发和血浆中观察到的皮质醇值低于泌乳母牛，结论是泌乳母牛比生长中的小母牛更容易受到热应激的影响。