The greatest amount of benefit gained by crossbreeding is with crossbred cows. Even though many stockmen use crossbreeding of straightbred parents to produce exceptional market calves (calves that gain faster than straightbreds and do well in the feedlot), the crossbred cow is the key to maximum beef production and profitability in a cow-calf operation, since hybrid vigor in the cow produces phenomenal maternal advantages.
Research has shown that a crossbred cow is eight percent more efficient than a purebred cow, lives 38 percent longer and has 25 percent more lifetime production (pounds of calf weaned). This is partly due to the fact that crossbreeding has the biggest impact on traits that are not highly heritable (and hence more difficult to improve through selective breeding within a breed), such as fertility, age at puberty, and longevity.
Crossbred cows live longer and are also less apt to be culled for being late or open, due to increased fertility. Any cow that can calve at two years of age, never miss a year of calving, and stay in your herd another year or two beyond average culling age makes you money. When you consider all the benefits of a crossbred cow, you can see why animal scientists call this the “only free lunch” in the cattle business. As pointed out by Dr. Larry Cundiff (U.S. Meat Animal Research Center, Clay Center, Nebraska), data from their heterosis studies showed that breakeven costs of production were reduced about 10 percent by using crossbred cows. Another study at Montana State University compared effects of breed and heterosis on heifer pregnancy using purebred and crossbred females of several breeds. Results showed that a higher percent of crossbred heifers calved at two years of age (reaching puberty and becoming pregnant earlier) than purebreds.
And if a cow is healthier, with a stronger immune system due to hybrid vigor, she develops better immunity when vaccinated, imparts better colostrum to her calf, which in turn keeps him healthier through the risky days of early calfhood. Genetics plays a big role in an animal’s immunity and immune response; the crossbred animal is hardier than a straightbred animal partly just because genes control the process of recognizing disease agents and inbreeding doubles up more of the undesirable immune-response genes. Every pure breed is inbred to some degree. Crossbreeding ensures more genetic diversity and optimal immune response. Thus a crossbred cow tends to have more optimum immune system function than a straightbred cow, and hence not only stays healthier herself but may also produce more protective colostrum.
When all factors are weighed, the crossbred cow gives you the most benefit. By contrast, the stockman who is merely trying to take advantage of hybrid vigor in the calves (using straightbred cows and bulls of another breed) gains less impact on profitability. Calf weaning weights for crossbred calves are five percent more (and yearling weights four percent more) than straightbred calves. The research study in the 1990’s that came up with these figures showed that a straightbred cow with a crossbred calf earned an average of $23.37 more than if she had a straightbred calf. But a crossbred cow with a crossbred calf netted $116.88 more than a straightbred cow with a straightbred calf. This is one reason a number of producers went to crossbred cow herds.
In the past decade, however, with increasing popularity of “black” cattle and the drive toward more uniformity and marbling, many of America’s commercial cow herds have lost most of the heterosis they once had. Due to market pressures for beef calves, many stockmen have been using bulls of just one breed, and the replacement heifers become more and more straightbred with each generation. According to Dr. Jim Gosey (retired Beef Extension Specialist, University of Nebraska), the loss of heterosis in these herds shows up most quickly in the traits that are least heritable (and most associated with inbreeding depression), namely reproduction (fertility), hardiness and longevity. The price paid for loss of heterosis is cumulative—as a number of very small losses add up and amount to a substantial sacrifice in lifetime productivity.
As one cattle buyer observed following a cold slow spring during which feed supplies were short, most of the cows in several herds he worked with were thin, and there was a high rate of open cows after the breeding season. Interesting to note, the cows that bred back the best, and on time (in spite of the tough conditions), were the old crossbred cows that were still in the herds. The younger females that were a high percentage of straight breeding didn’t do so well.
