Several models combined with ultrasound techniques to predict breast muscle weight in broilers

The weight of breast muscle ( WBM ) is a highly monitored indicator in broiler breeding that can be obtained after slaughtering. Currently, due to the lack of accurate in vivo phenotypes for both genomic and phenotypic selection, genetic gains in WBM fall short of initial expectations. In this study, 1,006 market-age (42 d) broilers from 3 generations over 2 yr were randomly selected, and the breast width ( BW ), fossil bone length ( FBL ), breast muscle thickness ( BMT ), and live weight ( LW ) were measured exactly in vivo. Eight models, including multiple linear regression ( MLR ), ridge regression ( RR ), least absolute shrinkage and selection operator ( LASSO ), and elastic net ( EN ), were fitted to explore the best regression relationships between breast muscle weight and these indicators. Support vector machine ( SVM ) methods with both linear kernels and radial kernels were used to fit the models, while 2 decision tree-based machine learning algorithms, random forest ( RF ), and extreme gradient boosting ( XGBoost ), were used to establish the prediction model. The predictive effects of different combinations of independent variables were compared, leading to the conclusion that the EN model achieves the best predictive power when all 4 live features are used as inputs and is slightly better than the other models ( R 2  = 0.7696). This method could be applied in practical production and breeding work, leading to substantial cost savings and enhancements in the breeding process.