Estimation of genetic parameters for longevity considering the cow's age at last calving.
The aim of this study was to estimate heritability and predict breeding values for longevity among cows in herds of Nellore breed, considering the trait cow's age at last calving (ALC), by means of survival analysis methodology. The records of 11,791 animals from 22 farms were used. The variable ALC has been used by a criterion that made it possible to include cows not only at their first calving but also at their ninth calving. The criterion used was the difference between the date of each cow's last calving and the date of the last calving on each farm. If this difference was greater than 36 months, the cow was considered to have failed and uncensored. If not, this cow was censored, thus indicating that future calving remained possible for this cow. The survival model used for the analyses was the proportional hazards model, and the base risk was given by a Weibull distribution. The heritability estimate obtained was equal to 0.25. It was found that the ALC variable had the capacity to respond to selection for the purpose of increasing the longevity of the cows in the herds.
Departamento de Ciências Exatas, Faculdade de Ciências Agrárias e Veterinárias (FCAV), Universidade Estadual Paulista (UNESP), Jaboticabal, SP, 14884-900, Brazil.
Sabrina L
SL
Caetano
Department of Dairy Sciences, University of Wisconsin, Madison, WI, 53706, USA.
Guilherme J M
GJ
Rosa
Departamento de Ciências Exatas, Faculdade de Ciências Agrárias e Veterinárias (FCAV), Universidade Estadual Paulista (UNESP), Jaboticabal, SP, 14884-900, Brazil.
Rodrigo P
RP
Savegnago
Universidade de Franca, Franca, SP, 14404-600, Brazil.
Salvador B
SB
Ramos
Departamento de Ciências Exatas, Faculdade de Ciências Agrárias e Veterinárias (FCAV), Universidade Estadual Paulista (UNESP), Jaboticabal, SP, 14884-900, Brazil.
Priscila A
PA
Bernardes
Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.
Luiz A F
LA
Bezerra
Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, 14049-900, Brazil.|ANCP - Associação Nacional de Criadores e Pesquisadores, Ribeirão Preto, SP, 14020-230, Brazil.
Raysildo B
RB
Lôbo
Instituto de Zootecnia, Centro APTA (Agência Paulista de Tecnologia dos Agronegócios) de Bovinos de Corte, Sertãozinho, SP, 14174-000, Brazil.
Claudia C P
CC
de Paz
Departamento de Ciências Exatas, Faculdade de Ciências Agrárias e Veterinárias (FCAV), Universidade Estadual Paulista (UNESP), Jaboticabal, SP, 14884-900, Brazil. danisio@fcav.unesp.br.
Danísio Prado
DP
Munari
D000367:Age Factors; D000818:Animals; D001947:Breeding; D002417:Cattle / Q000235:genetics*; D005260:Female; D005298:Fertility / Q000235:genetics*; D008136:Longevity / Q000235:genetics*; D008297:Male; D036801:Parturition; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000235:genetics*; D016016:Proportional Hazards Models
Beef cattle; Heritability; Survival analysis; Weibull model