Should a replacement heifer look like a well-fed steer ?

      When you put it that way, I expect you would all say “NO”.    According to Dr Jan Bonsma (late of South Africa (as well as Texas A&M) back into the 1970s), his studies in endocrinology (glandular functions)  led him to postulate,  “Bulls should look masculine, and the best ones will produce a cow that looks feminine.”    Cows with a “bully” (blocky) look generally do not have an optimal level of natural fertility, nor are they reliably “maternal” in behavior at and after calving.

Statistically, the beef “breed” with the poorest breeding record is the “Club Calf composite”.   It is not that surprising given that the primary genetic selection criteria in club calf breeding is the ability to grow coarse hair and the predominance of steer traits in the physique.   After a couple generations of such bulls, the retained females start to look more “clubby” than truly feminine.   With the decline of feminine qualities, natural fertility follows, and then maternal behavior.

Given the prevalence of CIDR use and OvSynch to get “clubby” females bred for optimal calving dates, loss of natural fertility  (which occurs gradually over generations)  is not always detected.   But it should be a consideration in which females you need for commercial beef replacements.

Growth rates are also not always as good in clubby herds as they might be in straight-bred cow herds, as well.    While the original clubby bulls  (representing three way crosses)  exhibited lots of hybrid vigor, this disappears when crossbred cows get bred to crossbred bulls over multiple generations.    Studies in both Beef and Dairy herds have shown that when using crossbred bulls we get better results in growth rates and the feminine quality of heifers if their dams are mostly purebred cows  (especially those sired by successfully linebred bulls).    

Maintaining heterosis  (hybrid vigor)  is easier when one side of the mating is linebred.    You get consistency from the linebred cows, while you get genotype variation from the crossbred bulls.    Clubby bull lines began from the desire to gain the heterosis possible from two and three way breed crosses among performance-type sires.     But the availability of straight-breed cows to be bred at that time is what made the whole process work spectacularly at first.