The impact of block calving on GB calf births

Wednesday, 25 August 2021

By Chris Gooderham

Overall calf births to dairy dams show peaks in the spring (Feb/Mar) and autumn (Aug/Sep). Over recent years we’ve seen these peaks increase, while births in May and June have been falling.

Breaking monthly calf registrations down by farm system, allows us to better understand what is driving the movement in overall calf births.

According to data from BCMS, 19.6% of calf registrations in 2020 on dairy farms came from those operating block calving systems. However, in the key calving months of Feb, Mar, Aug and Sep block calving herds can account for around a third of overall calf registrations. The proportion from block calving herds peaks in February at 37%. Conversely, the block calving herd share in June drops to just 5%.

What happens if more become block calvers?

The breakdown of calf registrations allows us to analyse what might happen if more of the non-defined herds move to block calving. The seasonality of calf births for block calvers means a small swing in herds can have a disproportionate impact on individual months.

The charts shows the impact of a 1% increase* in spring block or autumn block calving. It shows that February births would actually increase by 3.5% if we had 1% more spring block herds.

Often an increase in autumn block calving offsets the impact from an increase in spring block calving. However, this isn’t the case in May-Jul or Dec-Jan, where the two block calving systems both lead to a drop in monthly calvings.

Over the coming weeks we will review the impact on the GB milk production profile from the different systems.


* Assumes any additional block calvers come from the non-defined group

Image of staff member Chris Gooderham

Chris Gooderham

Head of Market Specialists - Dairy & Livestock

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