Isberg Sally R, Finger John W, Thomson Peter C
Centre for Crocodile Research, PO Box 329, Noonamah, NT 0837 Australia; School of Life and Environmental Sciences, Faculty of Veterinary Sciences, University of Sydney, NSW 2006, Australia.
School of Life and Environmental Sciences, Faculty of Veterinary Sciences, University of Sydney, NSW 2006, Australia; Department of Environmental Health Science, University of Georgia, Athens, GA, 30602, USA; Department of Biological Sciences, Auburn University, Auburn, AL, 36849, USA.
Gen Comp Endocrinol. 2018 Dec 1;269:96-101. doi: 10.1016/j.ygcen.2018.08.020. Epub 2018 Aug 23.
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.
在澳大利亚北领地的两个养殖场，对三种大小规格（幼鳄、生长鳄和可收获规格）的湾鳄（Crocodylus porosus）进行多次采血，以确定血浆皮质酮（CORT；鳄鱼应激激素）的参考水平。幼鳄（<1岁）、生长鳄（1 - 3岁）和可收获规格个体（2 +岁）的平均CORT值分别为1.65±0.15 ng/ml、2.73±0.21 ng/ml和2.19±0.16 ng/ml。在幼鳄或可收获规格的鳄鱼中未检测到养殖场间的差异，但养殖场2的生长鳄血浆CORT显著低于养殖场1的。然而，两个养殖场生长鳄的生长速率系数相同，因此重复采血设计很可能是导致CORT值差异的原因，而非任何管理程序。血浆皮质酮水平随时间显著升高。每次采样时均观察到血浆CORT存在显著差异，这在文献中并非没有先例，但需要进一步阐明。无论如何，由于CORT值总体较低，我们的结果表明，按照澳大利亚行业操作规范实施的养殖环境和饲养管理措施，作为动物福利的基线措施是有效的，尽管应将其视为进一步福利研究的基础，而不应视为一成不变。
