Quantitative analysis of production traits in saltwater crocodiles (Crocodylus porosus). II. Age at slaughter

• Published in: Journal of animal breeding and genetics (1986) 2005-12, Vol.122 (6), p.370-377
• Main Authors: Isberg, S.R, Thomson, P.C, Nicholas, F.W, Barker, S.G, Moran, C
• Format: Article
• Language: English
• Subjects: age at slaughter; Age Factors; Alligators and Crocodiles - anatomy & histology; Alligators and Crocodiles - growth & development; alternative livestock; Animal Husbandry - methods; animal performance; animal production; Animals; Body Weights and Measures; Breeding - methods; crocodiles; Crocodylus porosus; Environment, Controlled; Female; genetic improvement; heritability; hides and skins; Likelihood Functions; Male; Models, Statistical; morphometry; phenotypic correlation; Quantitative Trait, Heritable; width
• ISSN: 0931-2668; 1439-0388
• DOI: 10.1111/j.1439-0388.2005.00549.x

Summary Crocodile morphometric (head, snout‐vent and total length) measurements were recorded at three stages during the production chain: hatching, inventory [average age (±SE) is 265.1 ± 0.4 days] and slaughter (average age is 1037.8 ± 0.4 days). Crocodile skins are used for the manufacture of exclusive leather products, with the most common‐sized skin sold having 35–45 cm in belly width. One of the breeding objectives for inclusion into a multitrait genetic improvement programme for saltwater crocodiles is the time taken for a juvenile to reach this size or age at slaughter. A multivariate restricted maximum likelihood analysis provided (co)variance components for estimating the first published genetic parameter estimates for these traits. Heritability (±SE) estimates for the traits hatchling snout‐vent length, inventory head length and age at slaughter were 0.60 (0.15), 0.59 (0.12) and 0.40 (0.10) respectively. There were strong negative genetic (−0.81 ± 0.08) and phenotypic (−0.82 ± 0.02) correlations between age at slaughter and inventory head length.