title: Genetic parameter estimates  and response to selection for weight and testicular traits in Nelore cattle.
abstract: We  estimated genetic parameters for various phases of body and testicular growth  until 550 days of age in Nelore cattle, using Bayesian inference, including  correlation values and error estimates. Weight and scrotal records of 54,182  Nelore animals originating from 18 farms participating in the Brazilian Nelore  Breeding Program (PMGRN) were included. The following traits were measured:  weight at standard ages of 120 (W120), 210 (W210), 365 (W365), 450 (W450), and  550 (W550) days; weight gain between 120/210 (WG1), 210/365 (WG2), 365/450  (WG3), 450/550 (WG4), 120/365 (WG5), 120/450 (WG6), 120/550 (WG7), 210/450  (WG8), 210/550 (WG9), and 365/550 (WG10) days of age; scrotal circumference at  365 (SC365), 450 (SC450) and 550 (SC550) days of age, and testicular growth  between 365/450 (TG1), 450/550 (TG2) and 365/550 (TG3) days of age. The model  included contemporary group (current farm, year and two-month period of birth,  sex, and management group) and age of dam at calving, divided into classes as  fixed effects. The model also included random effects for direct additive,  maternal additive and maternal permanent environmental, and residual effects.  The direct heritability estimates ranged from 0.23 to 0.39, 0.13 to 0.39 and  0.32 to 0.56 for weights at standard ages, weight gains and testicular  measures, respectively. The genetic correlations between weights (0.69 to 0.94)  and scrotal circumferences (0.91 to 0.97) measured at standard ages were higher  than those between weight gain and testicular growth (0.18 to 0.97 and 0.36 to  0.77, respectively). The weights at standard ages responded more effectively to  selection, and also gave strong correlations with the other traits.
authors.affiliation: Departamento de Genética e Melhoramento Animal, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista Julio de Mesquita Filho, Jaboticabal, SP, Brasil. netozoo@hotmail.com
authors.forename: F R
authors.initials: FR
authors.lastname: Araujo Neto
authors.forename: R B
authors.initials: RB
authors.lastname: Lôbo
authors.forename: M D S
authors.initials: MD
authors.lastname: Mota
authors.forename: H N
authors.initials: HN
authors.lastname: Oliveira
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D001835:Body Weight / Q000235:genetics*; D001938:Brazil; D001947:Breeding; D002417:Cattle / Q000033:anatomy & histology* / Q000235:genetics; D056726:Genetic Association Studies; D005838:Genotype; D008297:Male; D008460:Meat; D008957:Models, Genetic; D010641:Phenotype; D019655:Quantitative Trait, Heritable; D015203:Reproducibility of Results; D012611:Scrotum / Q000033:anatomy & histology*; D013737:Testis / Q000033:anatomy & histology*; D014886:Weaning; D015430:Weight Gain / Q000235:genetics*