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ARS predicts forage growth

Evidence suggests early-weaned calves gain more efficiently than traditionally weaned calves.

Agricultural Research Service (ARS) scientists are developing technology to predict forage growth. It will allow ranchers to make more-informed rotational grazing decisions.

At the ARS Great Plains Systems Research Unit in Fort Collins, CO, researchers are developing a database to analyze historical and simulated data. The database will predict future forage growth, helping ranchers decide how many animals they can graze on native range.

The program will predict drought's effect on range, forage and livestock production. It incorporates 50 years of historical climate and soil data from several ARS Great Plains research locations. With more accurate predictions about forage growth potential in both drought and wet years, ranchers can adjust their management practices to reduce the impact of drought-related losses and maximize returns on the land.
ARS News Service

Numerous studies have examined the differences and benefits of early weaning over traditional weaning. Evidence suggests early-weaned calves gain more efficiently than traditionally weaned calves.

University of Missouri researchers took it a step further by evaluating growth rate, body composition and meat tenderness in early vs. traditionally weaned calves.

In the study, 140 spring-born Angus × Gelbvieh and purebred Angus steers were split into groups of early weaned (EW; average age at weaning of 90 days +/- 30 days) or traditionally weaned (TW; average age at weaning 170 days +/- 37 days). The steers were split further into non-implanted or implanted with Synovex-S.

Ultrasound measurements of the longissimus muscle area (LMA), 12th rib backfat thickness and marbling were collected every 28 days while steers were on feed. At 202 days of age, EW calves had larger LMA, fat thickness and body weight than TW steers (37.9 vs. 32.3 cm, 0.38 vs. 0.26 cm, and 271.6 vs. 218.9 kg, respectively). EW calves also had heavier hot carcass weights (290.4 vs. 279.7 kg, respectively) and greater USDA marbling scores than TW calves.

The study shows calves introduced to a high-concentrate/high-by-product diet at 90 days of age are heavier, have more 12th rib backfat and larger LMA at the time their contemporaries are weaned at a more traditional 174 days of age. The EW calves generated heavier carcasses and had a greater likelihood to grade USDA Choice or greater than TW steers.

Researchers say the improvements in hot-carcass weight, LMA and quality grade could be attributed to extra time in the feedlot. They say EW of steers can help effectively manage the cow-calf production system without compromising offspring quality.
Meyer et al. J. Anim. Sci.

High-quality forage can sometimes be hard to come by in Northern Plains states, such as Montana, where coarse rangeland can be dominated by tufts of native grass and sagebrush. But ARS rangeland scientists at Fort Keogh Livestock and Range Research Lab in Miles City are changing that.

Forage expert Marshall Haferkamp found seeded pastures, planted with well-adapted perennial grasses, can help round out a herd's yearly nutritional needs.

In southeast Montana, a rainy spring or extended summer drought will determine forage availability to cattle. By planting pastures with vigorous perennial grasses acclimated to the area, ranchers might be able to better manage pastures.

“We wanted to see how the released varieties of cool-season grasses would work in the Northern Plains in the spring and autumn, when the quality of native rangelands isn't high,” Haferkamp says.

He collaborated with plant breeders at ARS's Forage and Range Research Lab in Logan, UT, to select the perennial grasses used. They chose different spring and autumn cool-season cultivars, and the grasses were given two years to establish before being grazed.

In the end, the specially seeded pastures provided animals with better nutritional opportunities — allowing them to put on pounds during the spring and fall.

One surprise was animals on perennial pasture in the spring, then moved to native rangeland in the summer, weren't able to maintain their initial weight. When all the animals were grazing native rangeland, those that gained more slowly in spring were able to catch up to the faster-growing animals in the summer.

The scientists say one benefit of autumn-seeded pasture is the potential for pregnant animals to add weight going into winter.
ARS News Service

TAGS: Pasture