The quality of hay fed to a beef heifer the next 60 days of winter will determine the vigor of her calf to be born next spring-and whether she can rebreed to calve the next year.
The amount of fat on a heifer's back determines the care she needs, says Justin Sexten, University of Missouri Extension beef nutritionist. His concern includes condition of cows in a herd, but heifers pregnant with first calves need extra nutrition.
Sexten is concerned about the coming calf crop-for the next two years-because of drought last summer. Too many beef females are going into winter without protective layers of fat that help carry them through until spring grass.
For some, hay supplies are limited and quality low. A ration rich in nutrients allows cows to maintain body condition, keep the fat layer and develop a calf. Normally hay does that.
"Unfortunately, much forage harvested last season does not meet base requirements," Sexten says. Grain supplement will be needed if hay is not of adequate quality.
Herd owners judge the amount and what kind of feed that will be needed from body condition scores (BCS) of cows.
By rule of thumb, a heifer should calve at 85 percent of her mature body weight. Most herds target 1,300-pound mature cows. That mature weight is based on 5- to 8-year old cow at BCS 5 on a sale of 1 to 9. That means a goal of 1,200 pounds at calving for heifers-1,100 pounds of body mass plus 100 pounds of condition.
Growing heifers need more and better feed than mature cows. They should be fed separately from the cows, Sexten says.
Body condition scores are measured in 100-pound increments. Scoring estimates fat on the cow's body. If she is flat across the back with no backbone or ribs showing, she scores BCS 6 or better, a desired condition for calving.
However, if her backbone "splits a raindrop," she needs feed to add body fat before calving, Sexten says.
With normal summer and fall grass growth, heifers are grass fat by winter. Not this year. "During July and August, when no grass grew, heifers mined condition off their back," Sexten says.
Now heifers must not only be fed to support normal body and calf growth during winter, but also to replace lost fat.
Lost fat concerns Sexten. That energy source affects vigor of the calf at birth. Also, adequate body fat adds quality and quantity to milk the heifer provides her newborn calf.
Nutrition in that first 24 hours determines if a calf thrives, Sexten says. Spring-born calves come into a cold world. They need the rich energy and antibodies provided by colostrum, the first milk, to survive.