Researchers at the Centre for Genetic Improvement of Livestock (CGIL), University of Guelph in collaboration with BIO and Canadian Beef Sires (CBS) have developed two selection indexes that rank bulls for their profit potential using as many genetic factors as possible.

Both the Beef Builder Index and the Prime Plus Index are based on using a bull for two years in a typical Ontario cow herd (30 cows). Half of the heifer calves are marketed and half are used as replacements for the Beef Builder Index. For the Prime Plus Index the aim is to keep all heifers as replacements and market half of their heifer progeny in future years. All male calves are marketed as steers for both indexes.

The market target for the Beef Builder system is a 750 lb. carcass and single A marbling. Carcasses from the Prime Plus system were targeted to be lighter with higher marbling: 700 lbs AAA marbling. This produces a carcass with smaller portion sizes of highly marbled beef for the restaurant and hotel trade.

What is included in the indexes?

In order to create these selection indexes, many factors that influence the profitability of beef production in Ontario were used. The Bull Evaluation Program ABCs that are used in the calculation are birth weight, weaning gain, maternal milk, post-weaning gain, backfat, feed conversion (Arkell, New Liskeard and Kemptville), scrotal circumference, rib eye area and marbling. The costs used for the traits listed above included fixed and variable costs pre and post-weaning. The pre-weaning costs included fertility costs, calving costs, feed costs for the cow herd based on mature cow size and calf requirements. The post-weaning costs included the feedlot costs of feed and yardage, and factored in growth rate, market weight and feed efficiency. Each index is calculated as a Predicted Dollar Difference (PD$) which is the dollars of extra profit that will be generated by using this bull for two years compared to an average bull.

 

How do I use the index to select a bull?

To use the indexes, first of all decide if you want a Beef Builder or a Prime Plus bull. Then look at the bulls with a high PD$ and decide which ones have the combination of traits you want. You may want to put more or less emphasis on some traits. If that is the case, look through the top 10% or 20% of the bulls for PD$ and identify the ones that have the individual trait ABCs you feel you need. For example, suppose you feel that birth weight is a greater problem for your herd than on average. In that case you may want to look at the top 10% - 20% of the bulls and pick any which have a more negative ABC for birth weight. That way you’re still selecting for maximum profit and at the same time putting more pressure on birth weight.