Genetic improvement and prediction of dry matter intake in beef bulls.

摘要

Phenotypic evaluations of various models for the prediction of Dry Matter Intake (DMI) were performed. Genetic parameters were estimated for DMI, Average Daily Gain (ADG), Back Fat thickness (BF), Metabolic Mid-test Weight (MW), Test Weight (TWs), five predicted DMI phenotypes and five definitions of Residual Feed Intake (RFI). These genetic parameters were used to determine response in DMI under various selection scenarios including multiple trait selection with varying sources of data and RFI based selection approaches. It was determined that simple linear regression models with parameters estimated on the data of interest are appropriate for generating predicted DMI phenotypes for use in RFI or as indicators of DMI. Results from different selection scenarios indicate that selection for reduced DMI using a multiple trait index and data on DMI, ADG, BF, MW and TWs will generate the most genetic change in a breeding objective which places all economic value on DMI.