Dairy farmers do not recoup the rearing costs incurred from birth to 1st calving until 2nd lactation but varying proportions of 1st  lactation cows are removed from the herd. Our latest research highlighting the importance of fertility, including age at 1st  calving, on the progression of 1st lactation cows to 2nd lactation has been published in the international, peer-reviewed journal PLOS ONE. 

An InterHerd+ dataset derived from 500 milk recording dairy herds in UK was used to examine 1st lactation cows which calved in 2020. Of 29,128 1st  lactation cows, 82.6% remained within the herd and re-calved, 4.9% conceived but exited the herd before re-calving, 6.0% were served but exited the herd after failing to conceive and 6.6% exited the herd without being served.

The fertility data on these cows support the logical conclusion that farmers retain cows that are served and conceive sooner, possibly in order to keep within a broadly seasonal calving pattern. Cows which were served but not conceived had a median AFC 16–20 days greater than the median AFC for those that conceived. Farmers may also be retaining cows with relatively high milk yields and lower somatic cell counts, or these parameters may be an indicator of a range of attributes affecting the farmer’s decision.

The data also suggest that farmers are rearing more replacements than required, because over one third of the cows removed in first lactation are never served, and 70% of these are sold within 120 days post-partum. These cows had a significantly older median age at first calving of 818 days, but their early removal without serving suggests there is an oversupply of replacements forcing farmers to dispose of these cows early in lactation.

Published paper: Milk recording data indicates the importance of fertility, including age at first calving, on the progression of first lactation cows to second lactation | PLOS ONE