5 July 2002


COW replacement costs must include the difference in margins over concentrates of the cull and replacement heifer over a 12-month period.

Replacing a 7500 litre cow with a heifer yielding 1500 litres less will reduce margin over concentrates on that cow place by £218, says James Hague of the Kingshay Farming Trust. "Its crucial to bring the best heifers you can into the herd to maintain herd margins."

The ultimate replacement policy is to replace the lowest margin cows with animals which generate a higher margin. But typically 67% of culls are for forced reasons. "This reduces the scope to select low margin cows and forces the introduction of poorer heifers which otherwise would have been sold.

"But how do you identify low margin cows for culling? A good starting point is to calculate each cows milk income from 305-day yields and milk quality."

In a recent Kingshay study, the average herd showed 27% of animals had a Cow Production Index (CPI) below the average heifer. Using this measure together with cell count and persistent mastitis can narrow down your cull list, adds Mr Hague. &#42

Selecting higher yielding heifers will reduce the true cost of replacements, says James Hague.

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