Use COW rather than milk yield to cull cows
Milk yield alone is not a reliable measure to use when selecting cows for culling from a dairy herd. The culling tool, Cows Own Worth (COW), is a much more reliable means of identifying suitable cows for culling. George Ramsbottom, Teagasc Dairy Specialist talks about the ICBF generated tool here
The tool, generated by ICBF, incorporates not just milk yield but a number of other factors including the cow parity, SCC and EBI to develop a more balanced measure of suitable cows. In Table 1 we compare the results of selecting the bottom 10% of mature cows (from among 71 cows in their third or greater lactation) for culling based on either their milk yield or COW value from a 100-strong spring calving herd from South Kilkenny.
Table 1: Selection of bottom 10% of mature cows for culling from a herd selected either on lowest milk yield or lowest COW.
The data in Table 1 show that compared to the mature cow average, the cows with the lowest milk yield are predicted to produce 73 kg milk solids less than the mature cow average. However compared to the cows selected on COW, they are younger, higher EBI, earlier calving and have a lower somatic cell count. In other words, the COW identified the 10% of the mature cows that in their current and future lifetime in the herd likely to be less profitable for the herd owner. To use COW to select animals for culling, milk recording is essential. Recording scanning results prior to running COW will improve the value of the report that is generated as well. Now is an ideal time to run the report for spring calving dairy cows.
 Cows in their third or greater lactation.