Direct Heritability Estimates for Growth, Carcass and Precocity in Snails Cornu aspersum maximum (Synonym Helix...

The aim was to estimate the heritabilities for accumulated weight gain between 60 and 90 days (WG1), 90 and 120 days (WG2) and 120 and 150 days of age (WG3), pre-slaughter body weight (PRE), meat-to-shell ratio (MS), carcass yield (CY) and age at first oviposition (AFO) in a population of snails Cornu aspersum maximum. Single (for heritabilities) and bi-trait (for genetic correlations) analyses were performed using Bayesian inference. The animal model included the random effect of animal and systematic effects of contemporary groups and covariates. The heritability estimates for WG1, WG2 and WG3 were 0.59, 0.60 and 0.32, respectively. Heritabilities for PRE, MS, CY and AFO ranged from 0.22 to 0.51. Environmental factors mostly influenced PRE among the studied traits. However, for carcass traits and age at first oviposition, the 95% HPD intervals of estimates were large. Only the genetic correlations between weight gains reached chain convergence. The correlation between WG1 and WG2 was 0.74, between WG2 and WG3 was 0.57, and between WG1 and WG3 was 0.22 (not statistically significant). In this sense, WG1 appears to be the optimal period for evaluating the body performance of snails. Genetic improvement in WG2 may be obtained by direct selection for WG1 in this population of Cornu aspersum maximum.