Spayed heifers also finish and reach optimum grade sooner than intact counterparts, with the best gains coming in conjunction with implanting.
Feedlots prefer spayed heifers because pregnancies are no longer a management issue. A calving heifer costs a feeder $150-$200/head due to calving problems, infection, decreased gain, decreased carcass quality and yield.
“Preg-checking and administering abortifacients involve time and expense. It also stresses the heifers at a late point in their production phase — setting them back in weight gains. Spaying eliminates these problems. Producers can treat and manage spayed heifers just like steers,”says Meyer.
MGA is often given to intact heifers to suppress estrus, preventing ovulation. Feeding MGA results in increased feed efficiency and gain compared to other intact heifers, but isn’t approved for steers and can’t be fed to groups of mixed sexes.
Research indicates that spayed heifers’ performance advantage extends to both pasture and feedlot. “Some feedlot managers say spayed heifers stay on feed more consistently, more like steers. Even when feeding melengestrol acetate [MGA] to intact heifers to halt cycling activity, there’s variance in feed consumption. Spayed heifers, with more consistent intake, get more consistent feed conversion.”
Like steers, spayed heifers can be implanted, and respond better to implants than intact heifers. In fact, spayed heifers that are implanted tend to have more lean tissue and deposit less fat. One study showed average daily gain response to implants was four times greater in spayed vs. intact heifers. And grazing studies indicate a 5.5% gain advantage for spayed, implanted heifers over implanted, intact heifers, Meyer says.
"A combined average of studies over a seven-year period on spayed yearling heifers showed a 2.5%-3% gain advantage, and a 0.1-0.3 lb/day gain advantage for spayed, implanted heifers, if everything else is equal,"
For heifers destined for beef production rather than calf production, spaying has distinct advantages. Spayed heifers can be grazed or fed with steers without riding activity or worrying about the neighbor’s bull coming through a fence. Plus, heifers guaranteed as open and non-cycling draw premiums from some feedlot buyers.
Daryl Meyer, a North Platte, NE, veterinarian, spays tens of thousands of heifers in several states each year. He says spayed heifers generally are calmer than their intact counterparts. “They handle more like steers. They also gain better. If everything is equal, spayed females outperform intact heifers.”
Spaying heifers is a management tool that’s nearly a century old. It involves surgical removal of the ovaries — the primary source of estrogen and progesterone in females — thus eliminating estrous cycles and pregnancies.