Genetic analysis of survival potential of Boer x Central Highland goats under semi-intensive management

Abstract

Kid survival is very critical to be profitable in goat production. Thus, this study was conducted to identify genetic and non-genetic factors affecting the survival rate of Boer x Central Highland goat and to estimate genetic parameters for survival using linear animal and Weibull proportional hazard model. Data collected from the Sirinka goat breeding station were utilized for this study. Survival analysis was conducted with a Weibull proportional hazard model using Survival Kit version 6.1 software. The genetic parameters for survival traits were estimated using both Survival Kit fitted sire model and ASREML software fitted animal model with logit function. Four models for survival traits were fitted in order to optimize the model for each trait in the animal model. The loglikelihood ratio test was used for selecting the best-fitted model. The proportion of right-censored kids up to 3, 6 and 12 months of age was 77.8, 66.2 and 57.9 %, respectively. From the total death, about 73.1 % of death occurred up to 140 days of age. Gastrointestinal parasites, septicemia, pneumonia are the leading causes of death. Birth type, birth weight, dam breed and year of birth are the most important risk factors for kid mortality. Based on selected linear animal models, total heritability (h2 t) estimates for the survival of kids at 3, 6 and 12 months of age were 0.006, 0.096 and 0.098, respectively. The maternal permanent environmental effect explains 6% of the phenotypic variation in survival up to weaning age. However, the impact of the maternal effect on post-weaning survival was found to be negligible. The genetic correlation between birth weight and survival to yearling age was 0.55 ± 0.15. The heritability estimates for survival at 3, 6 and 12 months of age from the Weibull proportional hazard model were 0.10, 0.13 and 0.18, respectively. As both pre- and post-weaning survival traits are economically important traits, including in the selection index of the breeding program would be paramount. Besides selection, using a local goat as a dam line and improving management in the flock would be an option to improve the survival of kids.