Experts say producers have tools at their disposal to determine if heifers are mature enough to breed
When producers are planning out their breeding program, chances are that their heifers might give them pause. Are their youngest females old enough for breeding? Big enough? Prepared enough? These are all good questions to be asking before moving your heifers into your breeding program.
“We have excellent tools to determine their readiness thanks to beef reproduction research and local veterinarians,” said Eldon Cole, livestock specialist with the University of Missouri Extension.
These “tools” are referred to as pre-breeding exams.
“The vet does a rectal examination to estimate puberty status using the uterine horns and ovaries,” explained Cole, “This is a 1 to 5 system with a 1 being immature. A 2 is still quite small and not ready to breed, and 3s have larger ovarian follicles and larger uterine horns but still may not be ready for a high success rate for breeding at this time. The 4s and 5s have been in heat, and among a group of heifers, you’d like for at least one-half to be scored a 4 or 5 when your vet examines them.”
In addition to the tract scoring, Cole said, the vet can also measure the heifer’s pelvic dimensions, with a target size of 150 square centimeters. If you have some heifers that are a bit on the younger side but meet the tract score and pelvic score parameters, it is reasonably safe to include them in your breeding program.
As far as age goes, most experts are comfortable suggesting that heifers should be bred at 15 months, so they calve around 24 months of age.
“It’s suggested for best conception a heifer should have been in heat one or two times at least prior to bull or artificial insemination exposure,” noted Cole.
Some producers opt for heifers to calve at 3 years of age, however. According to Tom R. Troxel, Professor and Associate Department Head of Animal Science, and Shane Gadberry, Associate Professor of Animal Science with the University of Arkansas Division of Agriculture, “It has been shown that during the early period of life, cows calving first at 2 years of age have more difficulties at calving and produce fewer calves and less calf weight at first calving than cows first calving at 3 years of age. Cows calving at 2 years of age in the long run, however, tend to recover and surpass the cumulative performance of cows calving first at 3 years of age,” they have said.
There are pros and cons to both ages, and it really comes down to what fits each producer’s needs best.
While age and size are generally the first things producers consider when it comes to the breeding readiness of their heifers, body condition also needs to be factored in.
“Ideally, 2-year-old heifers should be in a body condition score of 6 at the time their first calf is born,” said Glenn Selk, Oklahoma State University Cooperative Extension emeritus livestock specialist. “This allows them the best opportunity to provide adequate colostrum to the newborn, repair the reproductive tract, return to heat cycles, rebreed on time for next year and continue normal body growth.”
To ensure the proper body condition, heifers require a different feeding program than the rest of the herd.
“First-calf heifers need to be fed separately from the mature cows and given a little better feed, pasture or hay,” advised Cole.