HEIFER MATING - the key to sustainable herd reproductive success!

It’s well recognised that most farmers have been struggling in recent years to maintain sustainable reproductive success in their dairy herds. Nearly ten years since the routine use of inductions ceased, many herds have seen empty rates steadily increase.

Herd reproduction is highly complex and multifaceted. If we consider heifer calving dates as a starting point, subsequent calving dates trend later and later with each year in the herd (as is expected with a seasonal, biological system). The aim of our efforts and interventions is to fight that trend, with an early start and tight calving pattern in the heifers and keeping subsequent calvings as early as possible.

Heifer mating (R2s, yearlings) is critical to achieving long-term, sustainable reproductive performance. It is interesting to note that heifer mobs usually get in calf relatively easily with low empty rates, compared to milking cows. However, the average calving date of heifers relative to cows varies a lot between farms. That is the area of focus for this article.

First-calvers take an extra ten days to start cycling after calving compared to mature cows. This is the reason behind the recommendation to begin heifer mating earlier than the dairy herd. We know that a cows first cycle after calving is not very fertile and that conception rates improve with consecutive cycles. For this reason, we like to see animals beginning to cycle well before the planned start of mating (PSM) and, by advancing the average calving date of the first-calvers to account for that ten day average delay, we have a hugely positive impact in this age group.

Synchronisation is another tool to advance the average date of first calving, with the added benefit of increasing the rate of genetic gain when using artificial breeding. The combination of early heifer PSM and synchronisation is very powerful and can result in roughly half of heifers calving before the planned start of calving (PSC) in the herd. New Zealand trial work has shown that synchronisation results in, on average, an extra three percent yearlings in-calf, 11 days more milk and 11 days extra time to begin cycling before PSM, 13kg more milk solids, less wastage as three year olds, and more AB calves.

A note on bull/semen selection: difficult calvings could potentially undo all the benefit derived from earlier mating and synchronisation. It is desirable for heifers to have low birthweight calves (it’s hard to beat Jersey) to minimise pain, physical damage and likelihood of uterine infections.

Once in the herd, remember to pay special attention to the first calvers as a group. Extra animal health inputs can help to cement their great start in the herd. Also remember that their body condition score target is 5.5 at their second calving and that they are likely to have the earliest expected calving dates on average – consider drying off heifers a few weeks earlier than the mature cows.

Summary of key points:

1.       Begin heifer mating 7-10 days prior to herd PSM

2.       Consider synchronisation to improve calving spread of first-calvers and allow for AB

3.       Ensure heifers are in-calf to easy calving bulls

4.       Pay special attention to first-calvers throughout their first lactation

Don’t hesitate to give us a call to discuss heifer PSM and synchronisation options, and how to ensure your heifers thrive throughout their first lactation.

Written by Reon McMurtrie