Creating a bespoke report to analyse heifer replacement KPIs is helping to focus producers’ minds on rearing during the post-weaning period. So which areas have be identified as requiring improvement?
TEXT BECCA CAVILL
The post-weaning phase when rearing heifers is critical to their development and future productivity as cows in the milking herd. Inadequate management during this period can stunt heifer growth, delay puberty and, ultimately, push the age at first calving beyond the target 24 months.
“Conversely, with close management, producers can ensure that heifers reach critical growth benchmarks, setting them on a trajectory to calve on time and to perform to their full potential in the milking herd,” says vet Emily Linton, from Devon-based Torch Farm Vets. Vet involvement when rearing replacement heifers often reduces once calves are weaned, and this is certainly Mrs Linton’s experience.
“Our practice runs a youngstock club, where herds are regularly visited to weigh pre-weaned calves, take bloods for total proteins and collect data on morbidity and mortality,” she says. “But once weaned, unless there was a health issue, the next time we’d see these heifers would be when they were presented for pregnancy diagnosis.” “If the heifers were between 13 and 15 months old and in calf – great. But if they were significantly older and/or not in calf then it was too late to do anything about it,” she adds.
So the practice team set out to better engage producers in their replacement heifers’ post-weaning period and began by assessing current performance. “We looked at herds’ current KPIs and then looked at how these figures related to industry targets and the unit’s own targets. That gave us a place to start for discussions about where and how improvements could be made.”
The team focused on three key KPIs: age at first calving (AFC), survivability and first-lactation yield. “The easiest figure to find in relation to AFC is a herd’s average figure,” says Mrs Linton. “We know the UK average AFC is 27 months and many of the herds we ran the data on were performing better than this. But this failed to present the full picture.”
Delving into the data revealed the spread of AFC and the percentage of heifers calving for the first time at 23 and 24 months old (see Figure 1 and Figure 2).
Figure 1: The spread of age at first calving for heifers born in 2018
Figure 2: Percentage of heifers born in 2018 that calved at target age
In-depth discussions
“This information allowed for more in-depth discussions with producers about their current management systems and what they were actually achieving,” she explains. “Although several herds had an average AFC of 24 or 25 months, which appears to show they were on top of things, when we looked more closely at the data we found that too many heifers were not, in fact, calving down at the target time and there was room for improvement.”
AHDB calculates the cost of rearing a heifer increases by £2.87 per day for every day increase in AFC above 24 months, due to additional costs in feed, labour and housing. “Heifers typically begin to ‘pay their way’ midway through their second lactation, so the sooner they enter the milking herd the more profitable they will be.” Mrs Linton says research that shows that heifers calving for the first time at between 23 and 24 months old produce more milk throughout their lifetime.
Aside from the economic benefits, there are also clear welfare advantages to calving heifers down at target age. “Older heifers are more likely to experience calving difficulties and there will be more replacements on the unit, creating overcrowding issues.
“There is also research on heifers calving at 30 months old that shows that they are twice as likely to leave the herd than heifers who calve at target age,” she says. There are several key areas producers can focus on to improve post-weaning heifer rearing and increase the likelihood of them entering the herd on time.
“Post-weaning nutrition is a key driver of growth during this critical period,” says Mrs Linton. “A ration comprising between 16% and 18% crude protein is recommended during the first few months post-weaning to support skeletal and muscular development.
“Adequate energy intake is also vital, with a balance of starches and fibre to promote healthy rumen function. Failing to feed enough concentrate and offering poor-quality forage are the two most typical issues we see in post-weaned heifer rations,” she adds.
“Producers should aim to optimise growth because both under-sized and over-conditioned heifers will create problems. Not all units have facilities to weigh heifers throughout this period, but marking withers-height targets on a shed wall is simple way to get around this.”
Post-weaning programmes
Successful post-weaning programmes not only hinge on nutrition but also on health management. Typical postweaning challenges include respiratory disease, parasitic infections, and digestive disorders. All can compromise heifer growth and delay reproductive milestones. Vaccination protocols, regular health checks, and biosecurity measures are essential to ensure heifers remain healthy during this period. “Respiratory diseases, in particular, are a common issue among young dairy calves, and research has shown that as the number of respiratory cases a calf incurs increases, the number of productive days decreases,” says Mrs Linton.
“How we manage heifers can also have a significant impact when it comes to meeting growth targets,” she adds. “Avoiding too many group changes, preventing overcrowding and minimising age ranges within groups can all contribute to reducing stress in heifers.
“Good conditions underfoot and optimal lighting will ensure that heifers feel confident in displaying bulling behaviour and will help to improve heat detection. And locking head yokes and synchronisation protocols can help to support fertility.”
By focusing on nutrition, health management, and genetics during the post-weaning phase, producers can ensure that heifers reach the target age of first calving. “And close attention here not only enhances the productivity and profitability of the herd, but also ensures that heifers transition smoothly into their role as high-performing dairy cows,” says Mrs Linton.
“We know how important investing in the preweaning period is to successful heifer rearing, and this investment must also continue throughout the postweaning phase to keep replacements on track.”
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