A two-year farm study has highlighted the importance to farmers of regular heifer weighing.

In 2015, the Agricultural and Horticultural Development Board (AHDB) Dairy kick-started its ‘Calf to Calving’ initiative to target more heifers calving by 24 months.

Heifers are cows that have not yet borne a calf or have only borne one calf.

Twelve dairy farms across the country, including Blackmarsh Farm in Sherborne, were enrolled in the project and acted as hosts for a series of farm meetings on best practice heifer management over the two years.

Results have identified huge variation in growth rates within batches of heifers.

Six farms were autumn block calving and enrolled in autumn 2015, and six had a stronger spring calving bias, enrolling in spring 2016. The growth, health and nutrition of 10 heifers on each farm were monitored every three months.

Growth data highlighted inconsistencies in growth rates within groups of heifers on individual farms, highlighting that many fail to hit the target growth rates needed to calve in at the most economical age of 24 months. Some of the key targets set included 50 per cent of mature body weight at 12 months old, 60 per cent at 14 months old and 85 per cent post calving.

AHDB Dairy’s technical manager Andy Dodd, who headed up the initiative said: “72 per cent of all heifers failed to achieve the target of doubling birth weight by weaning and half were not on target at each, three-monthly weigh point. There was also huge variability within groups. For example, on the Dorset farm, heifers were achieving between 0kg and 2kg of daily live weight gain at six to nine months of age.

On some farms, 12 to 15 month old heifers were also only achieving 0.1kg per day - well below the growth rate needed to hit the right weight to calve at 24 months.

Andy added: “The results from the 12 farms show it’s impossible to estimate weights by eye or spot variation in growth within a group by looking into a pen. Regularly weighing animals and managing heifers in weight groups is essential to make sure they stay on track.”

The need to continue to weigh animals at grass was also highlighted by the fact the biggest variability in growth rate was seen at the end of the summer across all heifers. It correlated with declining grass quality and insufficient supplementation.

Andy believes more work needs to be done to look at the affect of heifer genetics, however he advised closely monitoring weights at grass.

Visit www.dairy.ahdb.org.uk/c2c