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Capturing Hybrid Vigor in Cattle
Capturing the benefits of maximum heterosis is the breeding goal at J. Davis Cattle, Westminster, South Carolina. Heterosis is that hybrid vigor resulting from crossbreeding. It can result in enhanced performance in traits such as growth, fertility, longevity, and disease resistance.
After 16 years of focusing on strategic crossbreeding, Joe and Mandy Davis are seeing increasingly predictable results from planned crossing of Angus, Simmental, and Brangus (a Zebu-influenced breed originating from a crossing of Angus with Brahman cattle).
“For the past three years, our steers have gained 3.9 to 4.4 pounds per head per day in the feedlot,” says Joe Davis. “For each of the past two years, 99% and 95% have graded Choice or better. Along with that, the average age at harvest has gone way down, dropping from 549 days in 2015 to 460 days in 2017.”
Average carcass weight for the past three years has ranged from 900 to 927 pounds.
The Davises developed their three-way cross by choosing breeds representing differing regions of origin: a British breed, a Continental breed, and a Zebu-influenced breed.
“From the Angus breed, we believe we gain marbling, milk production, mothering ability, and relatively good muscling,” says Davis. “From the Simmental, we gain heavier muscling and good milk production. From the Brangus, we get strong mothering ability, disease resistance, longevity, and heat tolerance.”
The heat tolerance of the Brangus influence pays off during South Carolina’s 90°F. summer days. It also pays dividends in the feedlot, where the Brangus-influenced cattle are less likely to go off feed in warm or hot weather.
The Davises have bred uniformity into cattle by carefully managing the genetic influences to maintain maximum heterosis in an ongoing three-way balance.
“The breeding plan is a triangle,” says Davis. “The key is to breed each female to a sire of the breed she’s least related to, and that will be the breed of her great-grandsire. We record the sire, grandsire, and great-grandsire of every female.”
A color-coded breeding chart keeps the plan organized. The chart identifies the six cross-breeding sequences of a three-breed cross after a full six-year cycle of breeding females to the breed of their great-grandsire. It identifies in color-coded bars the breed of sire she should be bred to. The chart also shows the breed sequence of a resulting heifer and the breed of bull she should be bred to.
“At birth, heifer calves are tagged with an ear tag matching the color of the bar on the chart showing what breed of sire the heifer will be bred to for the rest of her life,” says Davis. “Our farms are divided by breed, too. We use Angus sires at one farm, Simmentals at a second farm, and Brangus at a third farm.”
Working with herd manager Mike Hall, the Davises bred 200 females in November and December of 2017 to calve next fall. With little or no hay, females graze year-round on 470 acres divided into 40 pastures. The pastures are further crossfenced to make up 155 paddocks.
Depending on forage availability, calves are weaned in spring at 176 to 220 days of age. Actual weaning weights range from 532 to 641 pounds.
Along with the replacement heifers, the stocker calves – the steers headed for the feedlot – are backgrounded on grass for 70 to 170 days. The young cattle are supplemented on grass with dried distillers’ grains.
“The stockers and replacement heifers provide a way to vary the stocking rate on the farm,” says Davis. “If we lack rainfall, we ship steers early to the feedlot and sell extra heifers earlier, leaving forage for the rest of the herd. Because we have converted the farms to novel fescue varieties, the fescue is nontoxic, so we don’t have to worry about grazing fescue in summer.”
Stocker cattle are sent to a Kansas feedlot at weights ranging from 700 to 785 pounds. The Davises retain ownership of the cattle through finishing, and they receive individualized feeding and carcass data on the steers. Heifers not kept as replacements are sold at local auction barns.
All breeding females are synchronized for timed artificial insemination. Ten days after breeding, females are exposed to cleanup bulls in single-sire pastures. The breeding season for heifers is 45 days and 65 days for cows. “We cull females that don’t settle during this time,” says Davis.
Other culling criteria include udder and foot structure, disposition, calf performance, and frame score.
“We keep a close handle on frame scores of both cows and bulls,” says Davis. “We avoid extremes in either direction because we’re looking for balance in the frame of the cattle.” They look for a frame score of 6 or lower.
“All our cattle are registered with the American Simmental Association in their Plan D program for commercial cattle,” says Davis. “As a result, we have EPDs on all our cattle, and we use these in our selection and breeding programs.”
The Davises are positioning their operation to be a source of three-breed-cross females for other producers. Full transparency to potential buyers is their aim. To that end, their website (jdaviscattle.com) contains detailed information about their herd management and includes individualized data for their cattle.
“We want to produce high-value replacement heifers as best we know how,” says Davis. “Our faith in God motivates us to do our best.”
In crossbred cattle, heterosis gives a performance kick that can amount to as much as 20% more than the performance of straightbred cattle.
“Heterosis tends to be most evident in traits that have low heritability,” says Jennifer Thomson, beef geneticist at Montana State University.
Such traits include reproductive ability and longevity.
“As a result of heterosis, you might expect to see a calving rate increase of 4%,” she says. “From two-way crosses, you can expect to get one extra calf in the lifetime productivity of the cow. That can also come in the form of added weaning weight of calves over the lifetime of the cow.
“Maximum individual heterosis can be achieved when you have 50% of one breed in a mix of other breeds,” she says. “Maximum retained or overall heterosis can be achieved with a three-breed rotational breeding system.”
The effective breed mixes can include only British breeds, only Continental breeds, a crossing of British and Continental, and, of course, the possible inclusion of Zebu-influenced breeds.
“The idea is to select breeds with complementary characteristics that further your selection goals,” says Thomson. “The more dissimilar the breeds are genetically, the more heterosis will result from the cross.”