Estimation of variance components for carcass and production traits in Guzerat cattle

The Guzerat cattle breed, in past centuries, was utilized in Brazil mainly for work and transport in the coffee industry because of its rusticity; however, in recent decades it has become important for milk and meat production. Cattle traits such as rib-eye area, backfat thickness, and intramuscular fat percentage have been continuously evaluated in breeding programs because they are related to meat quality, carcass yield and organoleptic properties; however, the Guzerat breed has not been included in this type of study. In order to overcome these limitations, we estimated variance components, genetic correlations and heritability for ribeye area (REA), backfat thickness (BFT), rump fat thickness (RFT), intramuscular fat percentage (IMF), dry matter intake (DMI), average daily gain (ADG), scrotal circumference (SC), metabolic weight (MW), visual score for finishing (VSF), residual feed intake (RFI) and margin (MAR) from 1499 animals of the Guzerat breed. Genetic parameters and trait heritabilities were estimated using data collected from various breeders for each trait. The dataset was analyzed by the AIREMLF90 program. REA and MAR were the carcass and production traits with the greatest additive genetic variance; they also had the highest heritability values. The average inbreeding of animals in pedigree was 0.81%; more than 71% of animals had 0% inbreeding and only 0.04% of the animals had a coefficient over 25%. Carcass and production traits of Guzerat cattle analyzed in this study showed sufficient genetic variability to respond to a selection program, especially for the traits REA, RFT, IMF and ADG. Thus, selecting animals based on data obtained from this study will help improve Guzerat carcass quality, production efficiency and profit margins.