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Survival analysis of productive life in Florida dairy goats using a Cox proportional hazards model

Survival analysis of productive life in Florida dairy goats using a Cox proportional hazards model Longevity is an economically important trait, since extending the functional life of a doe would allow us to keep the most productive females in the herd as long as possible, and this could result in the increased profitability of dairy farms. Thus, the objectives of this study were to determine the most important factors that influence the length of productive life (LPL) of female Florida goats and to estimate its genetic additive variance using a Cox proportional hazards model. The data consisted of 70,695 productive life records from 25,722 Florida females kidding between 2006 and 2020. A total of 19,495 does had completed their productive life while 6227 (24.2%) does had censored information. The pedigree contained information on 56,901 animals. The average censoring age and average failure age after first kidding for LPL were 36 and 47 months respectively. The model included, as time‐independent effects, the age at first kidding and the interaction between herd, year and season of birth of the doe, and as time‐dependent effects, the age at kidding, the interaction between herd, year and season of kidding, the within‐herd class of milk production deviation, and the interaction between the lactation number and the stage of lactation. All fixed effects had a significant effect on LPL (p < 0.05). Does with older ages at the first kidding and an earlier age at kidding were at higher risk of being culled. A large difference among herds was observed in terms of culling risk, which highlighted the importance of adequate management practices. Also, high‐producing does were less likely to be culled. The estimate of the additive genetic variance was 1.844 (in genetic standard deviation), with a heritability estimate of 0.58 ± 0.012. The results of this study are expected to contribute to the development of a genetic model for genetic evaluation of the length of the productive life of Spanish dairy goat breeds. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Animal Breeding and Genetics Wiley

Survival analysis of productive life in Florida dairy goats using a Cox proportional hazards model

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References (39)

Publisher
Wiley
Copyright
Copyright © 2023 Wiley‐VCH GmbH
ISSN
0931-2668
eISSN
1439-0388
DOI
10.1111/jbg.12769
Publisher site
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Abstract

Longevity is an economically important trait, since extending the functional life of a doe would allow us to keep the most productive females in the herd as long as possible, and this could result in the increased profitability of dairy farms. Thus, the objectives of this study were to determine the most important factors that influence the length of productive life (LPL) of female Florida goats and to estimate its genetic additive variance using a Cox proportional hazards model. The data consisted of 70,695 productive life records from 25,722 Florida females kidding between 2006 and 2020. A total of 19,495 does had completed their productive life while 6227 (24.2%) does had censored information. The pedigree contained information on 56,901 animals. The average censoring age and average failure age after first kidding for LPL were 36 and 47 months respectively. The model included, as time‐independent effects, the age at first kidding and the interaction between herd, year and season of birth of the doe, and as time‐dependent effects, the age at kidding, the interaction between herd, year and season of kidding, the within‐herd class of milk production deviation, and the interaction between the lactation number and the stage of lactation. All fixed effects had a significant effect on LPL (p < 0.05). Does with older ages at the first kidding and an earlier age at kidding were at higher risk of being culled. A large difference among herds was observed in terms of culling risk, which highlighted the importance of adequate management practices. Also, high‐producing does were less likely to be culled. The estimate of the additive genetic variance was 1.844 (in genetic standard deviation), with a heritability estimate of 0.58 ± 0.012. The results of this study are expected to contribute to the development of a genetic model for genetic evaluation of the length of the productive life of Spanish dairy goat breeds.

Journal

Journal of Animal Breeding and Genetics – Wiley

Published: Jul 1, 2023

Keywords: Cox model; dairy goat; genetic parameters; productive life

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