title: Genetic parameters for milk, fat and protein yields in Murrah buffaloes (Bubalus bubalis Artiodactyla, Bovidae).
abstract: The objective of the present study was to estimate genetic parameters for test-day milk, fat and protein yields and 305-day-yields in Murrah buffaloes. 4,757 complete lactations of Murrah buffaloes were analyzed. Co-variance components were estimated by the restricted maximum likelihood method. The models included additive direct genetic and permanent environmental effects as random effects, and the fixed effects of contemporary group, milking number and age of the cow at calving as linear and quadratic covariables. Contemporary groups were defined by herd-year-month of test for test-day yields and by herd-year-season of calving for 305-day yields. The heritability estimates obtained by two-trait analysis ranged from 0.15 to 0.24 for milk, 0.16 to 0.23 for protein and 0.13 to 0.22 for fat, yields. Genetic and phenotypic correlations were all positive. The observed population additive genetic variation indicated that selection might be an effective tool in changing population means in milk, fat and protein yields.
authors.affiliation: Faculdade Ciências Agrárias e Veterinárias, Universidade Estadual Paulista Júlio de Mesquita Filho', Jaboticabal, SP Brazil.
authors.forename: Rusbel Raúl
authors.initials: RR
authors.lastname: Aspilcueta-Borquis
authors.forename: Roberta Cristina
authors.initials: RC
authors.lastname: Sesana
authors.forename: Milthon Honorio Munoz
authors.initials: MH
authors.lastname: Berrocal
authors.forename: Leonardo
authors.initials: L
authors.lastname: de Oliveira Seno
authors.forename: Annaiza Braga
authors.initials: AB
authors.lastname: Bignardi
authors.forename: Lenira El
authors.initials: LE
authors.lastname: Faro
authors.forename: Lucia Galvão
authors.initials: LG
authors.lastname: de Albuquerque
authors.forename: Gregório Miguel Ferreira
authors.initials: GM
authors.lastname: de Camargo
authors.forename: Humberto
authors.initials: H
authors.lastname: Tonhati