title: Genetic correlations between  mature cow weight and productive and reproductive traits in Nellore cattle.
abstract: We  investigated genetic associations between mature cow weight (MW) and weaning  weight (WW), yearling weight (YW), weight gain from birth to weaning (GBW),  weight gain from weaning to yearling (GWY), weaning hip height (WHH), yearling  hip height (YHH), scrotal circumference (SC), and age at first calving (AFC).  Data from 127,104 Nellore animals born between 1993 and 2006, belonging to  Agropecuária Jacarezinho Ltda., were analyzed. (Co)variance components were  obtained by the restricted maximum likelihood method, applying an animal model  in a multi-traits analysis. The model included direct genetic and residual  effects as random effects, the fixed effects of contemporary group, and the  linear and quadratic effects of animal age at recording (except for AFC, GBW,  and GWY) and age of cow at calving as covariates (except for MW). The numbers  of days from birth to weaning and from weaning to yearling were included as  covariates for GBW and GWY, respectively. Estimated direct heritabilities were  0.43 ± 0.02 (MW), 0.33 ± 0.01 (WW), 0.36 ± 0.01 (YW), 0.28 ± 0.02 (GBW), 0.31 ±  0.01 (GWY), 0.44 ± 0.02 (WHH), 0.48 ± 0.02 (YHH), 0.44 ± 0.01 (SC), and 0.16 ±  0.03 (AFC). Genetic correlations between MW and productive traits were positive  and of medium to high magnitude (ranging from 0.47 ± 0.03 to 0.71 ± 0.01). A  positive and low genetic correlation was observed between MW and SC (0.24 ±  0.04). A negative genetic correlation (-0.19 ± 0.03) was estimated between MW  and AFC. Selection to increase weight or weight gains at any age, as well as  hip height, will change MW in the same direction. Selection for higher SC may  lead to a long-term increase in MW. The AFC can be included in selection  indices to improve the reproductive performance of beef cattle without  significant changes in MW.
authors.affiliation: Departamento de Zootecnia, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista, Jaboticabal, SP, Brasil. iregatieri@hotmail.com
authors.forename: I C
authors.initials: IC
authors.lastname: Regatieri
authors.forename: A A
authors.initials: AA
authors.lastname: Boligon
authors.forename: F
authors.initials: F
authors.lastname: Baldi
authors.forename: L G
authors.initials: LG
authors.lastname: Albuquerque
mesh_terms: D000375:Aging / Q000235:genetics*; D000818:Animals; D001835:Body Weight / Q000235:genetics*; D002417:Cattle / Q000235:genetics* / Q000254:growth & development*; D005260:Female; D040582:Inheritance Patterns / Q000235:genetics; D008297:Male; D010641:Phenotype; D019655:Quantitative Trait, Heritable; D012098:Reproduction / Q000235:genetics*