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OVERTON – Recently completed research here shows stocker cattle can gain more than 1,000 pounds per acre in 60 days grazing Tifton 85 bermudagrass.
That 1,000 pounds per acre was at a high stocking rate with protein supplementation, said Dr. Monte Rouquette, the Texas Agricultural Experiment Station scientist who conducted the grazing study. Without supplementation, at the same stocking rate, stockers gained only 560 pounds per acre, said Rouquette, who is based at the Texas A&M University System Agricultural Research and Extension Center at Overton. The research was part of Rouquette's on-going work on looking at how plant and animal systems interact under various management systems.
In the world of forage and beef cattle research, studies done on different supplementation rates are frequently conducted. Most studies look at various ranges of supplementation at the same stocking rate.
Rouquette's study, however, took a different tack, and varied the stocking rates instead. Rouquette used 110 crossbred cattle, fall-born and weaned in mid-June, and given standard vaccinations for the study. Starting weight per animal in the study averaged about 650 pounds. Pastures used were harvested for hay in May, and the standard fertilization regimen followed.
Then, Rouquette did something different. The usual practice is to turn cattle in for grazing when the bermudagrass grows 4 to 6 inches tall. Instead, Rouquette let the bermuda-grass reach 14 to 16 inches—hay-cutting height. The Tifton 85 reached this height by late June, thanks to plentiful rainfall.
"In effect, we grew for a hay harvest, but harvested the forage with cattle," Rouquette said.
Rouquette used three different stocking rates, low, medium and high, for the study. The stocking rate was defined not in terms of the numbers of animals per acre, but in the number of pounds of animal per acre.
The low stocking rate was about 3,500 pounds per acre (four to five animals per acre); the medium 5,100 pounds (seven to eight animals per acre); and the high 6,500 pounds (nine to 10 animals per acre). Half the cattle in each stocking rate received a daily supplement of 1 percent of their body weight. As the cattle gained weight, the total amount of supplementation was adjusted accordingly each month. The supplementation was composed of a 2-to-1 ratio of soybean meal and corn.
The supplementation was enhanced with salt, minerals and Rumensin 80.
Over the next 60 days, the average daily gain of the cattle at the high stocking rate with supplementation was 1.7 pounds; those without supplementation gained 0.9 pounds.
"This equaled 1,060 pounds of beef produced per acre in 60 days for those with supplementation and only 560 pounds per acre for those without," Rouquette said.
The average daily gain of the cattle at the medium stocking rate with supplementation was 1.88 pounds; without supplementation, 1.06 pounds. The 60-day total equaled 970 pounds per acre for those receiving supplementation; 490 pounds per acre for those without supplementation. The average daily gain of the cattle at the low stocking rate with supplementation was 2.2 pounds; without supplementation, 1.7 pounds. The 60-day total per acre equaled 750 pounds per acre for those receiving supplementation; 550 pounds per acre for those without supplementation.
"From previous studies, average daily gain was just about what we would expect on low stocking rates," Rouquette said. "What's interesting in this study was that though we planned on having our typical droughty conditions in mid-summer, we received hardly any rain at all in the three months of the study."
During the last 30 days of the study, average daily gains were severely reduced because of slowed forage growth.
"If we had received any rain at all, the gains at the end of 90 days would have been even better, (particularly) on the high stocking rates," he said.
For producers, Rouquette said, the bottom line of the study is that when cattle are expensive, supplementation pays, especially when using a high-quality warm season forage such as Tifton 85.
"With stocker cattle prices at about $1 per pound and pasture-plus-supplementation costs at less than 30 cents per pound of gain, backgrounding 60 to 90 days on Tifton 85 puts profit back into the pasture-cattle business," he said.
Rouquette will soon have data from a similar study using yearling Brahman steers. The steers were spring-born, carried through on winter pasture to the spring, then observed under similar research design on Tifton 85.
"The high-stocking rates with supplementation were even more exciting," Rouquette said.
How exciting? Rouquette doesn't want to go into details until he's thoroughly double-checked his analysis, but he expects gains of about 1,300 pounds per acre in 60 days.
