Does the 50/50 rule still apply in cattle breeding now that carcass grids are becoming the rule in valuing terminal animals? Will the steer that is 50 percent British and 50 percent exotic perform as profitably on the rail as on the ranch? If not, what is the new rule?

I have been looking into these questions in recent columns, drawing information from a data bank on terminal animals fed to finish under the OK Feedout sponsored by the Oklahoma State University extension service. Hopefully, this information will provide some guidance to those of you who are wondering about crossbreeding for the grid era.

Here's where we've been so far. In my February column, I presented a valuing example using quality and yield data on 161 British and British-on-British cross steers and 100 exotic and exotic-on-exotic cross steers. This example illustrated a value difference of $12.60 favoring the British cattle when priced on the IBP Real Time Grid.

This example was valuable because it illustrated how breed-related carcass differences can influence carcass value. The strength of the example was that it was based on real values gathered and reported on individual steers. But the weakness of this example was that it merely compared British breeds and exotic breeds as groups without focusing on particular crossing combinations.

I expanded my database to four years for my March column. I also included factors that influence carcass values indirectly and other factors that must be taken into consideration in making crossbreeding decisions. I presented the first information from this data set in my March column. More of this data is presented in this column and others will be presented in future columns.

The table in my March column showed that in the 912 steers quality grade was highest where the percentage of British genetics was highest (particularly high Choice and Prime). Conversely, yield grade was highest where the percentage of exotic genetics was highest (particularly Yield Grade 1). There is nothing surprising in principle about these data, as even your coffee shop consultants would agree. But you'll find some surprising things in these data if you study them closely.

Our educational exercise now continues as we compare live weights, dressing percentages, average daily gains and feed conversion ratios (see table above).

Anything surprising in the data on live weights? Probably not. Most straight exotics are bigger cattle than straight British. A British bull on an exotic cow increases weaning weight over a straight British calf. An exotic bull on a British cow decreases weaning weight over a straight exotic calf. An exotic bull on an exotic cow of a different breed doesn't make much difference. I'm surprised that this effect is not seen in the British on British situation. Heterosis may be involved here but so may be the smallness of the sample.

The data on dressing percentage have reasonable symmetry, in my view. Exotic genetics enhance dressing percentage. The reasons for this advantage will become clearer next month when we compare the breed groups on such factors as backfat thickness, KPH fat and ribeye area.

There may be surprises for some of you in the data on average daily gain and feed conversion. Do British genetics really have an advantage over exotic genetics in these economically important areas? They do in this real set of cattle.

These are all interesting comparisons but taken individually, they are incomplete as a basis for designing crossbred cattle for the grid era. But taken together, including those that will be discussed in coming columns, they should prove very useful. More next month!

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