Genetic analysis of residual feed intake adjusted for fat and carcass and performance traits in a Nellore herd/Analise genetica do consumo alimentar residual ajustado para gordura e de caracteristicas de carcaca e desempenho em um rebanho Nelore

• Published in: Ciência rural 2017-02, Vol.47 (2)
• Main Authors: de Moraes, Giovanna Faria, Abreu, Luiza Rodrigues Alves, Ferreira, Isabel Cristina, Pereira, Idalmo Garcia
• Format: Article
• Language: English
• ISSN: 0103-8478
• DOI: 10.1590/0103-8478cr20151505

The study of the genetic evaluation of residual feed intake adjusted for fat (RFIFat) is important for the appropriate use of feed efficiency in selection programs. The objective was to analyze the influence of selection for RFIF at on carcass and performance traits by estimating various genetic parameters. Data were analyzed from five tests of feed efficiency, which were conducted with 677 Nellore males. Genetic evaluation was performed by Bayesian inference using an animal model via single- and two-trait analyses. Variables analyzed were dry matter intake, average daily gain, RFIFat, rib eye area, back fat thickness, rump fat thickness, marbling score, and subcutaneous fat thickness. The posterior mean distributions estimated at each analysis were used to estimate heritability of the traits and to perform various correlations. The studied traits showed high heritability estimates, and they should respond well to selection. The RFIFat presented a phenotypic correlation with carcass traits (which was next to zero), and there was also a negative genetic correlation. Additive genetic variability for RFIFat showed that selection for this trait can promote genetic gains in future generations, resulting in animals that are efficient in terms of nutrient use, and according to the genetic and phenotypic correlations, with no significant negative changes to carcass traits. Key words: back fat thickness, feed efficiency, genetic correlation, heritability. O estudo da avaliacao genetica do consumo alimentar residual ajustado para a gordura (CARFat) e importante para o uso apropriado da eficiencia alimentar em programas de selecao. Objetivou-se analisar a influencia da selecao para CARFat sobre caracteristicas de carcaca e de desempenho, frente a estimacao dos parametros geneticos. Foram analisados os dados de cinco provas de eficiencia alimentar, com 677 machos Nelore. A avaliacao genetica foi realizada por Inferencia Bayesiana, com modelo animal, em analises uni e bicaracteristica. Foram analisadas as variaveis: ingestao de materia seca, ganho de peso diario, CARFat, area de olho de lombo, espessura de gordura, espessura de gordura subcutanea na picanha, marmoreio e acabamento. As medias das distribuicoes a posteriori, estimadas em cada uma das analises, foram usadas para a estimacao das herdabilidades e das correlacoes. As caracteristicas estudadas apresentaram altas estimativas de herdabilidades, devendo responder bem a selecao. O CARFat apresentou correlacoes fe