Joe Kelleher: How many replacements do we need?
There has been a lot of focus this spring on improving the beef traits of the non-replacement calves produced from the national dairy herd.
The key recommendations include using sexed semen, using more beef AI, using the dairy beef index to choose bulls, and only generating enough heifers to meet your replacement requirements. But how many replacement heifers are required on your farm?
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There are numerous factors that will determine the number of replacements required on our dairy farms; the fertility status of the herd, the age profile, disease status, calving spread, expanding herd or static, farmers' own desire to improve the genetics of their herd.
The list goes on. Having assessed all these factors, every farmer should have an idea of the number of heifer calves they wish to see on the ground in spring 2020.
When you know the number of heifer calves you want, you can then start to plan how many cows you need to serve to dairy sires. To illustrate the point, the table below goes through an example for a 100-cow herd.
The starting point for this exercise is to enter the number of heifers you want in the parlour in spring 2022. In this situation, the farmer is not expanding and has an empty rate typically of 10pc.
Therefore, 10 heifers are required to replace those that do not go back in calf. She/he also wishes to cull a few late calvers and to allow room to replace some lame cows, high SCC cows and low protein cows, so she/he has decided that a further 10 heifers will achieve this.
To achieve 20 heifers successfully standing in the parlour in 2022, this farmer has decided they need to calve down 21 heifers to allow for the one heifer that may calve down with blind quarters or may meet some other fate at calving.