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Rancher’s Management Guide Cattle Herds can Benefit from Crossbreeding Programs By DONALD STOTTSFor the average cow-calf producer looking to increase the profit potential of his or her herd, the message is clear: crossbreeding can produce a 20 percent increase in pounds of calf weaned per cow exposed to a herd sire. Most of the increase occurs from improved reproductive performance; however, 25 to 40 percent of the increase is the effect of heterosis on growth potential of the crossbred calf and increased milk production of the crossbred cow. Heterosis is the average superiority of a crossbred individual over the average of breeds involved in the cross. Heterosis results in a better-performing animal. "An economic evaluation of crossbreeding showed that a 16 percent to 20 percent increase in net income after taxes could result through effective use of crossbreeding," said Kent Barnes, Oklahoma Cooperative Extension Service area livestock specialist. A number of crossbreeding systems are not feasible in herds of 25 animals or fewer with access to only one breeding pasture. Still, it is possible to maintain a high level of heterosis in a small single-sire herd. "The easiest, though not the most economical, method for a single-sire herd is the purchase of crossbred females as herd replacements," Barnes said. Two-way cross females are mated to a bull of a third breed to produce three-way cross calves. Maximum heterosis is expressed in the cows and calves. "This system is the simplest and easiest to manage when a good source of replacement crossbred females can be located," Barnes said. He said there are a number of herds in Oklahoma [and Texas] that have 20 to 40 cows and only one breeding pasture, each of which can potentially benefit from three possible crossbreeding management options. One system involves the rotation of two breeds, another involves the rotation of three breeds and, the most simplified system, use of a three-breed composite. In each system a new bull is introduced every two years to avoid mating heifers back to their sire. Barnes said the single-sire two-breed rotation is expected to yield 59 percent of maximum individual heterosis and 47 percent of maximum maternal heterosis. The single-sire three-breed rotation should produce 77 percent of maximum individual heterosis and 60 percent of maximum maternal heterosis. "This compares to 72 percent of maximum individual heterosis and 56 percent of maximum maternal heterosis obtained from a two-breed rotation in a large herd or through artificial insemination," he said. "It's proven that single-sire rotations can increase productivity and profitability in small beef herds," he said. Different breeds, but similar types Choice of biological type is important, in addition to obtaining the heterosis by crossing the breeds. "Biological type and performance should be similar for all breeds being used," Barnes said. "This is important because bulls will be bred to both heifers and cows for calving ease. "The choice of biological type should match the most economical feed and production environment," he said. Although traits with a low heritability respond very little to genetic selection, studies show they exhibit a marked improvement in a sound crossbreeding program. "Commercial producers need to select sires carefully in order to improve traits with a high heritability and use a well-planned crossbreeding program in order to use heterosis effectively while matching biological types to the most cost-effective environments," Barnes said. An exerpt from "Crossbreeding Systems for Beef Cattle" By PETER T. ANDERSON, Extension Animal Scientist, University of Minnesota Crossbreeding offers two primary advantages: heterosis (also called hybrid vigor) and the opportunity for breed complementarity. When the performance of crossbred offspring exceeds the performance of the purebred parents, the difference is called heterosis. In other words, the whole can be greater than the sum of the parts. For instance, if straightbred Hereford and Angus calves average 500 pounds at weaning and Hereford x Angus calves average 525 pounds, the heterosis realized is (525-500)/500, or 5 percent. Low heritability traits The more diverse the parent breeds are, the greater the heterosis will be. The best example of this is mixing of Bos taurus and Bos indicus (such as Brahman) breeds. Since these breeds actually represent different species, their great diversity will result in tremendous heterosis. Conversely, crossing of Hereford x Polled Hereford or Angus x Red Angus will result in less heterosis than crosses such as Hereford x Charolais or Angus x Simmental.
"Rancher's Management Guide: Cattle Herds Can Benefit from Crossbreeding Programs" is from the August 2008 issue of The Cattleman magazine.
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