Multi-trait Prediction of Feed Conversion in Feedlot Cattle

It’s time for the beef industry to catch up with those of swine and poultry, which have systems in place to alter feed conversion, said William Herring, University of Florida geneticist, in remarks to Beef Improvement Federation (BIF) members in Omaha July 12.

Referring to his profit selection index work with Circle A Angus Ranch of Iberia, Mo., Herring described ways to prioritize selection emphasis aimed at maximizing profit in terminal Angus systems. The work serves as an example in the development of an expected progeny difference (EPD) for feed efficiency.

A handful of traits—dry matter intake, weight gain, feed conversion, feed efficiency and net feed intake—describe the area of focus, he said. 

“Calculating feed conversion by mathematical model is problematic,” Herring said, because low dry matter intake can be mistaken for favorable feed conversion. Net feed intake measurements are better, but require observation and records.

Citing no phenotypic relationships for feed conversion, Herring said the traits tend to be moderately to slightly heritable, depending on breed types, and moderately correlated to yearling weight and feed intake. Working from the strong correlation between dry matter intake and residual feed intake, Herring designed progeny testing for Circle A’s Angus Sire Alliance.

He used the Miles City (Mont.) Experiment Station SIMUMATE computer model to gauge the effect of trait selection on profitability, characterizing high- and low-profit sires by applying weighted averages to economically relevant EPDs.

Measuring efficiency is more difficult in beef cattle than pork or poultry, but Herring said his work with the Angus Sire Alliance indicates a 10% improvement in feed conversion could lead to savings of $120 million annually.
— by Steve Suther