How have changes to calving patterns affected milk production?

By Felicity Rusk

There has been a marked change in the calving patterns of the GB dairy herd in the past five years. Compared to the 2015/16, a higher proportion of cows calved during the autumn (August/September) and spring block (February/March) in the 2019/20 season. There has also been a reduction in the proportion of calvings in the month’s in-between these peaks.

In 2020, 21.5% of the GB cows calved in August and September, up from 20.3% in 2015. Meanwhile, in February and March of this year, 19.3% of the GB cows calved, up from 18.7% in 2015. This is likely a reflection of a number of producers moving towards from all-year round to block calving systems as well as producers tightening up their calving window.

Milk yields peak around 8-weeks post calving, these shifts in calving patterns will have knock on effects onto the GB milk production profile.

By using our milk forecasting calculator and assuming no change in milk yields, we can model how the changes in calving patterns could have impacted milk production at a national level. 

The higher proportion of cows calving in the spring and autumn blocks leads to higher milk production in the three months following these periods. In October and November, the combined increase in GB milk production is estimated to be over 19 million litres. It also estimates that milk production would be lower in the months in between these peaks.

However, milk production is influenced by many more factors than just calving pattern. As a result, the actual changes we have seen over the 5-year period do not necessarily line up with what the calculator expected. Nevertheless, the changes in calving pattern are likely one of the key drivers to the sizable growth seen in November milk production this year, and subsequently behind our upwards revision to our 2020/21 milk production forecast.

Sign up to receive the latest information from AHDB.