Two-trait random regression model to estimate the genetic association of scrotal circumference with female reproductive performance in Nelore cattle.
In an attempt to determine when scrotal circumference (SC) could be a reasonable indicator of female reproductive performance, a series of two-trait random regression model (regression for SC on age at measurement) using Gibbs sampling was applied to field data of Nelore cattle raised in a tropical environment. The female traits evaluated were age at first calving (AFC), first calving interval (FCI), heifer pregnancy (HP), and stayability (STAY). The posterior means of heritability of female traits ranged from 0.15 for AFC to 0.46 for HP and were about 0.50 for SC. The posterior means of genetic correlations between SC and AFC, FCI, HP, STAY were up to -0.70, -0.25, 0.48, and 0.29, respectively. Genetically, SC could be a reasonable indicator of female puberty (e.g., HP) as long as it is measured at a young age (400-440 days). However, for female reproductive traits measured at an older age (e.g., STAY), SC is merely a modest or even poor indicator. The use of sire expected progeny differences for female reproductive traits will be more effective than the use of expected progeny differences for SC to improve the reproductive performance of female cattle.
Grupo de Melhoramento Animal de Mato Grosso (GMAT), Instituto de Ciências Agrárias e Tecnológicas, Campus Universitário de Rondonópolis, Universidade Federal de Mato Grosso, Rondonópolis, Mato Grosso, Brazil. Electronic address: 10mario@gmail.com.
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ML
Santana
Grupo de Melhoramento Animal e Biotecnologia (GMAB), Faculdade de Zootecnia e Engenharia de Alimentos, Departamento de Medicina Veterinária, Universidade de São Paulo, Pirassununga, São Paulo, Brazil.
J P
JP
Eler
Grupo de Melhoramento Animal de Mato Grosso (GMAT), Instituto de Ciências Agrárias e Tecnológicas, Campus Universitário de Rondonópolis, Universidade Federal de Mato Grosso, Rondonópolis, Mato Grosso, Brazil.
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AB
Bignardi
Grupo de Melhoramento Animal e Biotecnologia (GMAB), Faculdade de Zootecnia e Engenharia de Alimentos, Departamento de Medicina Veterinária, Universidade de São Paulo, Pirassununga, São Paulo, Brazil.
J B S
JB
Ferraz
D000818:Animals; D002417:Cattle / Q000033:anatomy & histology / Q000502:physiology*; D005260:Female; D008297:Male; D009929:Organ Size / Q000235:genetics*; D012044:Regression Analysis; D012098:Reproduction / Q000502:physiology*; D012611:Scrotum / Q000033:anatomy & histology*; D012741:Sexual Maturation
Genetic correlation; Pregnancy; Puberty; Threshold model; Zebu