We break down the impacts of heifer mating and pre-calving weights on reproductive performance and milk production.
Having early calving cows that get in-calf year after year and stay in the herd is everyone’s aim. To do this, we all know heifers need to hit their weight for age targets, calve as two-year-olds and reach their lifetime full potential.
Reproductive performance and milk production are directly impacted by heifer mating and pre-calving weights.
Every 1% increase in hitting live weight targets equates to 2kgMS, in her first lactation. Underweight heifers have poorer reproductive performance and are more likely to leave the herd early. If a heifer is 10% off her target live weight that’s 20kgMS missed out on, and that’s if she makes in into the herd.
To break even on their rearing costs alone, heifers must stay in the herd until the end of their second lactation, but it’s when they become a highly productive and profitable four to eight-year-old cow that they really contribute.
The main considerations
Herd effect: This means how the heifers are managed. All your good work pays off! Management has the biggest effect on hitting target live weight compared to breeds or the region. Improving young stock management should lead to increased milk production and fertility, so keep at it!
Birth date: It’s obvious, but the later in the season a calf is born, the fewer days she has to reach puberty and be a well-grown heifer at mating. Consider this when making mating management decisions – can later cycling cows be bred to non-replacement semen? Or how will you manage later born heifer replacements for higher daily gains?
Time of Puberty: This is heavily influenced by weight. The sooner she hits approximately 50% of her mature live weight, the sooner she starts cycling.
Breed: Research has shown that Jersey and cross-bred calves are more likely to meet target live weights than Friesians.
What gets measured gets done and gives results: Heifers without live weight records are more likely to leave the herd. The only reliable way to monitor growth rates and be able to respond is to weigh individual animals using scales every six to eight weeks.
More weighing is happening every year, with more heifers hitting their weight for age targets. Feedback from farmers who have start weighing consistently is that they are getting better heifer growth. Keep at it!
To see if there is opportunity on your farm, assess your culling and wastage data by age group and see if you are happy with heifer performance and retention.
More detail can be found here.