Choosing the right replacement heifers can make or break herd productivity. New insights highlight why pre-breeding exams — done before the first breeding season — are vital to identify early-maturing heifers, reduce calving issues, and improve lifetime performance.
Thapelo Kgosi Ramokala, animal health specialist at Beefmaster Group, says pre-breeding exams are essential to improving herd fertility.
According to Thapelo Kgosi Ramokala, animal health specialist at the Beefmaster Group, there are three critical assessments to help primary producers select the best replacement heifers for long-term herd health and profitability.
"The ideal for cow producers is to have one calf per cow every year,” says Ramokala. “Farmers should also aim to keep productive cows in the herd for as many years as possible."
He believes the key lies in selecting the right heifers. "To set yourself up for success, you should choose a heifer that reaches puberty by 15 months so that she can calve at around 24 months,” he explains. “But 35% of heifers don’t reach puberty by then."
This is where pre-breeding exams come in – ideally performed between 12 and 15 months of age, before artificial insemination or bull turnout. These include a general evaluation, a target weight check, a reproductive tract score, and pelvic measurements.
"Heifers that conceive late in their first breeding season will calve late, and are more likely to conceive late again or not at all in future seasons," Ramokala warns.
Pre-breeding evaluation
Ramokala recommends performing the exam four to six weeks before breeding starts. “During this time, heifers should be screened for health or structural issues, as well as any temperament problems that may have developed during growth or been missed during post-weaning assessments.”
Target weight attainment
Reaching a target weight before breeding is essential for puberty. Ramokala stresses this weight should be specific to the individual animal – not just an average – and based on breed, biological type and herd goals.
“The recommended target is 65% of the cow’s mature body weight,” he says. “Generally, heifers should reach 80–85% of mature weight before calving.”
Reproductive tract scoring
A more accurate indicator of puberty than weight alone is the reproductive tract score, done by a veterinarian four to six weeks before breeding. "This score ranges from one to five and gives a direct evaluation of reproductive maturity," explains Ramokala.
The exam involves a transrectal palpation. If the heifer scores one, it means that she has an infantile reproductive tract, while a score of two means she is pre-pubertal or more than 30 days from reaching puberty.
"If she scores three, the heifer is still pre-pubertal, but is within the 30-day mark of reaching puberty,” he says. “A score of four means she has reached puberty, but has only reached the follicular phase of the menstrual cycle, while a score of five means she has reached puberty and attained the luteal phase."
Pelvic measurement
Pelvic measurement is another vital management strategy to minimise calving difficulties. This is done by a vet using a pelvimeter.
"The heifer’s pelvis should be large enough for her mature size, the calf’s expected birth weight and ease of delivery," says Ramokala. At the pre-breeding exam, the minimum pelvic area should be 150 cm². By the start of the breeding season, around 90 days later, this should grow to at least 180 cm².
However, bigger pelvises can signal bigger cows, which may not always be cost-effective. "Larger cows consume more feed and cost more to maintain, which is not always ideal for commercial operations," he notes.
That’s why pelvic measurement should be a screening tool, not a selection tool, says Ramokala.
A good replacement heifer should reach puberty by 15 months, calve at 24 months, and grow into a long-term, productive asset.
"Early born heifers tend to grow faster, conceive earlier, and stay in the herd longer. Using pre-breeding exams helps you boost fertility, reduce calving issues and cut long-term costs."
