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Abstract：
Saltwater crocodiles (Crocodylus porosus) across three size categories (hatchlings, grower and harvest-size) were repeatedly blood sampled on two farms in the Northern Territory, Australia to determine reference plasma corticosterone (CORT; crocodilian stress hormone) levels. The mean CORT values for hatchlings (<1 year old), growers (1-3 years) and harvest-size individuals (2 + years) were 1.65 ± 0.15 ng/ml, 2.73 ± 0.21 ng/ml and 2.19 ± 0.16 ng/ml, respectively. No inter-farm differences within the hatchling or harvest-size crocodiles were detected, but growers on Farm 2 had significantly lower plasma CORT than those on Farm 1. However, the grower growth rate coefficients were the same across both farms so the repeated blood sampling design most likely contributed to the difference in CORT values rather than any management procedures. Plasma corticosterone levels significantly increased with time of day. Substantial variation in plasma CORT was observed at each sampling which is not unprecedented in the literature but requires further elucidation. Irrespective, as CORT values were generally low, our results suggest that the farming environment and husbandry practices, as implemented under the Australian industry Code of Practice, are effective as baseline animal welfare measures although they should be viewed as a foundation for further welfare research and not considered static.
摘要：
咸水鳄鱼（Crocodylusporosus）分为三个大小类别（幼体，种植者和收获大小）在北领地的两个农场反复进行血液采样，澳大利亚确定参考血浆皮质酮（CORT；鳄鱼应激激素）水平。幼体(<1岁)的平均CORT值，种植者（1-3年）和收获大小的个体（2年以上）为1.65±0.15ng/ml，2.73±0.21ng/ml和2.19±0.16ng/ml，分别。在孵化或收获大小的鳄鱼中未检测到农场之间的差异，但是农场2的种植者的血浆CORT明显低于农场1的种植者。然而,两个农场的种植者生长速率系数相同,因此重复的采血设计最有可能导致CORT值的差异,而不是任何管理程序.血浆皮质酮水平随着一天中的时间显著增加。在每次采样中观察到血浆CORT的实质性变化，这在文献中并非前所未有，但需要进一步阐明。不管，由于CORT值普遍较低，我们的结果表明，农业环境和畜牧业实践，根据澳大利亚行业行为准则实施，作为基准动物福利措施是有效的，尽管它们应该被视为进一步福利研究的基础，而不是静态的。
