How do you do that? I'm still dealing with this question, which was asked early this year by some of my readers who were wondering whether the breeds in their crossbreeding programs were right for the emerging era of value-based marketing.

To date, I have presented information on five performance categories of 1,335 steers fed over a period of six years in the OK Feedout, a project of the Oklahoma State University Cooperative Extension Service. Because over 70 breeds and breed combinations are represented in these feedouts, the data have been summarized in six groups, as shown in the accompanying table.

The categories covered in previous columns were quality grade, yield grade, dressing percent, average daily gain and feed conversion. This column deals with another set of five performance categories-ribeye area, ribeye ratio, backfat thickness, kidney-heart-pelvic fat (KPH) and retail yield.

There are a number of reasons why it is important to look at ribeye area, which will become obvious as we move along in this column. First, ribeye area is an accepted indicator of carcass muscularity. Second, carcass muscularity, not backfat, is the most effective way of building profitable dressing percentages. Third, breed types vary significantly in their ribeye sizes.

As shown in the accompanying table, the exotic breeds had significantly larger ribeyes in the cattle of this study. But there is an aspect of the ribeye consideration that is generally over-looked-ribeye ratio (ribeye square inches divided by carcass hundredweights). The ribeye ratio of OK Feed-out steers has been as low as 1.5 in very lightly-muscled pens and as high as 2.2 in heavily-muscled pens. A ratio of 1.7 has been specified as the value threshold in a packer-conducted cutout study.

The deceptiveness of raw ribeye data can be seen in the table. Whereas the ribeye area of straightbred
exotic steers was almost 1 square inch greater than straightbred British steers, the two types were virtually equal in ribeye ratio. This was because the ratio for the exotics was figured off a 711-pound carcass and that of the British was figured off a 675-pound carcass.

A significant difference between breed types can be seen in the averages for back-fat thickness and KPH percent in the table. Note that the British steers carried an average of 1.6 inch more back-fat and had a significantly higher KPH percent than the exotics. Did these fat differences rather than muscularity affect the dressing percentages of the two groups? Probably. The dressing percentages of the British steers and the exotics, which were nearly identical at 63.49 and 63.45 respectively, would have favored the exotics had the fat quantities been the same.

But, there is more to these ribeye and fat factors than meets the eye. Hidden in the minds of the procurement people in the packing industry is a net figure on the amount of total retail product being purchased. An equation developed at Kansas State University uses backfat thickness, KPH fat, ribeye area and hot carcass weight as factors in an equation that answers this question. This equation shows that the packer gets 2.6 pounds more retail product per 100 pounds of carcass weight with the straight exotic carcasses in the table below than with the straight British carcasses. This difference translates into an advantage of three cents per pound for each point of difference in retail product between the two carcasses.

Like all comparisons we now have seen in this analysis, those in this column cannot be considered alone. The packer's grid considers them in combination, and this must be the rule in your plan for your crossbreeding program.

There will be more on this subject next month.

To contact Fred Knop, write Drovers or send e-mail to fredlyn@aol.com