Risk factors and genetic parameters of longevity in Spanish dairy goat breeds using a Weibull proportional hazards model

Abstract

The aim of this study was to assess the most important risk factors that influence productive life (PL) and to estimate genetic parameters for PL using a Weibull proportional hazards model in two Spanish dairy goat breeds belonging to different production systems. The dataset consisted of 70,695 and 49,176 lactation records of Florida and Payoya females, respectively, collected over the last two decades. A total of 6,227 (24.21%) Florida and 3,452 (20.42%) Payoya females had censored information. The pedigree included a total of 56,901 animals for Florida and 59,957 for Payoya. The effects included in the model for both breeds were the age at first kidding and the herd-year-season of birth of the doe as time-independent effects; and the age at kidding, the herd-year-season of kidding, the within-herd class of milk production deviation and the combination between the lactation number and the duration of lactation as time-dependent effects. Estimation of genetic parameters was made using a Weibull proportional hazards model using Survival Kit V6.0 software. The results from the Weibull animal models gave estimates of additive genetic variances of 0.99 ± 0.0003 and 0.156 ± 0.021, which corresponds to a heritability of 0.43 ± 0.025 and 0.11 ± 0.021 for Florida and Payoya, respectively. The magnitude of heritability obtained for PL suggests that a substantial response to selection may be expected for longevity, especially in the Florida breed. These results may contribute to the development of a routine genetic evaluation to improve PL in Spanish dairy goat breeds.

HIGHLIGHTS

• A Weibull proportional hazards model has been used to analyse productive life in Spanish goat breeds raised under different production systems.

• Productive life is influenced by many factors, with milk production the most important.

• According to the heritability estimated, a significant genetic response could be obtained by direct selection for productive life, especially in the Florida breed.

Keywords:

• Productive life
• genetic parameters
• weibull model
• dairy goat

Ethical approval

This study did not require manipulation or any change in the usual handling of the animals, since we have worked directly with the routine records provided by the breeders’ associations of the Florida and Payoya breeds.

Acknowledgments

The authors thank the ACRIFLOR (Asociación Nacional de Criadores de Ganado Caprino de Raza Florida – National Association of Florida Goat Breeders) and the ACAPA (Asociación de Criadores de Raza Caprina Payoya – Association of Payoya Goat Breeders) for kindly providing the data used in this study.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available on request from the corresponding author with the permission of ACRIFLOR (National Association of Florida Goat Breeders) and ACAPA (Association of Payoya Goat Breeders).