Tip of The Day - October 3, 2016

Photo by Tom Semadeni

Fawm hiding

1987 Performance Tested Beef Bulls

Paola de Rose and Jim Wilton looked at the possibility of adverse effects of selection and pre-test environment on the evaluations of station tested bulls, and to study models for evaluating beef bulls.

Pre-weaning and average daily gain on test were available on 5,082 bulls, representing six breeds, tested in Ontario and Manitoba between 1970 and 1985. Pre-weaning average daily gains were also available on 14,493 male herdmates that did not go into the test stations. Significant selection of bulls on the basis of pre-weaning ADG was found in 34% of all herd-years. In the models, only the within herd-year component of environmental carryover was addressed. The between herd-year component would also affect station performance.

With both selection and carryover effects present, animal models were used to evaluate bulls. A single trait model for gain on test and a two-trait model for pre-weaning gain and test station gain were used. Another two-trait model incorporating maternal grandsire (MGS) information was also included. A correlation of .84 between the best model and the current ROP index was found. Animal models resulted in re-rankings of bulls, and these could influence future rates of genetic change.

Photo by Tom Semadeni

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