Centre for Genetic Improvement of Livestock
Update 2000

Targeting Top-Notch Beef
by
Ariana Murata

"Weight gain rates will vary for each animal, depending on growth conditions and genetic make-up."

Prof. Steve Miller, Centre for the Genetic Improvement of Livestock, has developed a beef cattle evaluation method that considers the dynamic nature of biological traits such as growth, feed intake and body composition for potential breeding bulls. By studying dynamic or changing traits, an individual bull's progress can be followed over time, rather than focusing on static or fixed measurements.

Focus on the Final Product

Traditional beef cattle genetic evaluations consider characteristics such as birth weight or fat thickness measured only at one year of age. They give greater importance to these checkpoints rather than the desired end product: a beef steer that has attained an optimal weight and fat thickness for market. With repeated measurements of dynamic traits over the life span of bulls on test, the accuracy of genetic evaluations will improve.

"Weight gain rates will vary for each animal, depending on growth conditions and genetic make-up," says Miller. "Overall, a beef steer's weight and fat thickness will only matter once it's ready to go to market - not at birth, or when it's one year old."

On a four-month research study at Armidale, Australia in 1998, Miller analyzed data -- previously collected by Australia's Beef Cattle Cooperative Research Centre -- on 3,000 steers. Uniquely, this Centre had taken repeated carcass trait measurements (between the period of weaning to slaughter) for each steer with the use of ultrasound -- a costly but effective procedure. Carcass measurements included weight, growth rate, back fat depth, and rib-eye area. Analysis of the data gave Miller insight into the usefulness of repeated ultrasound measurements to improve the genetic evaluation of bulls.

Now, as a continuation of his study, Miller is taking similar measurements from steers at the Elora Research Station, University of Guelph. The data collected at Elora will help Miller expand and validate the work he did in Australia and hopefully show that the usefulness of multiple carcass measurements outweigh the cost of using ultrasound.

Beef Improvement of Ontario's Bull Evaluation Program has data collected on 50,000 bulls since the 1970s. Ultimately, the program's goal is to select the most promising bulls for breeding stock. Miller hopes his research will also contribute to this information database and overall, help to genetically improve beef cattle in Canada.

"Previously, we were mainly concerned with back fat depth, rib-eye area, and marbling measurements at a year of age," says Miller. "This novel genetic evaluation model will allow us to be more flexible and ultimately, more efficient at predicting carcass traits in commercial steers."

This research was sponsored by The Meat Research Council of Australia, as well as Beef Improvement Ontario, with matching funds provided by the Natural Sciences and Engineering Research Council.