Isberg S R, Thomson P C, Nicholas F W, Barker S G, Moran C
Centre for Advanced Technologies in Animal Genetics and Reproduction (ReproGen), Faculty of Veterinary Science, University of Sydney, NSW, Australia.
J Anim Breed Genet. 2006 Feb;123(1):44-7. doi: 10.1111/j.1439-0388.2006.00557.x.
Mortality records of 1302 juvenile crocodiles were available for analysis. Crocodiles that were slaughtered during this study were treated as censored (n = 2151). Additionally, records from animals that had neither died nor been slaughtered, i.e. were still alive in the production system (n = 1582), were censored at the last date of data collection. There were a total of 3733 censored records. The data were all full-sib records from 29 parental pairs from Janamba Croc Farm (Northern Territory, Australia), collected over nine consecutive years. Data were analysed using an extension of Cox's proportional hazards model to include frailty (random) terms to account for genetic effects. Heritability of log survival time for juvenile crocodile survival was 0.15 (SE 0.04). The probability of a juvenile crocodile surviving to day 400 was estimated to be only 51%. These results are the first to quantify juvenile survival in a captive breeding situation. Also, this is the first heritability estimate of crocodile survival and is a fundamental element in the development of a genetic improvement programme.
有1302条幼年鳄鱼的死亡记录可供分析。在本研究期间被宰杀的鳄鱼被视为截尾数据（n = 2151）。此外，那些既未死亡也未被宰杀，即在生产系统中仍存活的动物记录（n = 1582），在数据收集的最后日期被截尾。总共有3733条截尾记录。这些数据均为来自澳大利亚北领地贾纳姆巴鳄鱼养殖场29对亲本的全同胞记录，是连续九年收集的。使用扩展的考克斯比例风险模型对数据进行分析，该模型纳入了脆弱性（随机）项以考虑遗传效应。幼年鳄鱼存活的对数生存时间的遗传力为0.15（标准误0.04）。估计一条幼年鳄鱼存活到第400天的概率仅为51%。这些结果首次对圈养繁殖情况下的幼体存活率进行了量化。此外，这是首次对鳄鱼存活率进行遗传力估计，并且是遗传改良计划制定中的一个基本要素。
