Bred replacement heifers that will calve in January or February should be in a body condition score six at the time their first calf is born.
“This allows the heifers the best opportunity to provide adequate colostrum to newborns, repair the reproductive tract, return to heat cycles, rebreed on time for next year and continue their normal body growth,” said Glenn Selk, Oklahoma State University Cooperative Extension cattle specialist.
Heifers should be gaining 1.0 to 1.5 pounds per head per day, from now until calving time. That means heifers will need supplemental protein if their major source of forage in the diet is bermudagrass, native pasture or grass hay.
If the forage source is average in quantity and quality, 6 percent to 9 percent crude protein, heifers will need about 2 pounds of a high-protein supplement containing 38 percent to 44 percent crude protein each day.
“Remember that winter weather increases the animal’s nutrient requirements; the base recommendation will probably need to be increased with higher quality hay such as alfalfa or additional energy feed such as 20 percent range cubes to offset the effects of bad weather,” Selk said.
Soybean hulls or wheat mids also may be used to help ensure adequate energy intake by pregnant heifers. Yes, wheat pasture – provided there is sufficient growth from rainfall – can be used as a supplement for pregnant replacement heifers, provided it is used judiciously.
Selk said judicious use is important because pregnant heifers consuming full feed of wheat pasture will gain about 3 pounds per head per day; however, the heifers can become very fat and may suffer from dystocia if they are left on the wheat too long.
“Wheat pasture can be used more efficiently for gain of stocker cattle or weaned replacement heifers,” he said. “If wheat pasture is used for bred heifers, use it as a protein supplement by allowing the heifers to access the wheat on alternate days.”
Some cow-calf producers have reported that one day on wheat pasture and two days on native grass or bermudagrass work well.
“It makes sense,” Selk said. “This encourages the heifers to rustle in the warm season pasture for the second day, rather than just stand by the gate waiting to be turned back into the wheat pasture.”
Whatever method is used, the ultimate goal is to get a healthy calf on the ground while having the bred heifers in good body condition by calving so that they will grow into fully developed, productive cows.
“Producers need to remember that the 2-year-old heifers are handicapped because their teeth are in the process of changing from baby teeth to adult teeth,” Selk said.
Additional information from OSU Cooperative Extension on cattle management is available at http://beefextension.com  on the Internet or by contacting any local OSU Cooperative Extension county office, usually listed under “County Government” in telephone directories.