Selection for Growth and Feed Efficiency in Broiler: Realized Heritability and Responses of Selection

Abstract

The trait of body weight at a fixed age under ad libitum feeding is becoming less attractive due to accumulating negative impact of traits correlated to body weight. The correlation between weight gain and fat deposition is low but positive. The main goal of this study was to estimate genetic parameters, realized heritability and responses of selection. Data consisted of two selection lines in broiler, namely body weight (BW) and feed conversion ratio (FCR) lines. Estimation of genetic parameter was calculated by ASREML procedures based on animal model. Estimation of heritability was calculated through the regression of phenotypic means on cumulatively differential selection. Responses of selection were estimated by using average breeding value at each generation. Estimated heritability for body weight was 0.42 for BW line and 0.59 for FCR line, respectively. Estimated heritability for feed conversion was 0.44. However, there was an inconsistency between estimated and realized heritabilities. All traits measured had small-realized heritability, even they were negative for body weight and feed conversion in FCR line. The realized heritability for body weight in BW line was 0.10, while those for body weight and feed conversion in FCR line were -0.14 and 0.03. Genetic correlation between body weight and feed conversion ratio was 0.18, whereas phenotypic correlation showed no difference to 0.