Wastage, length of productive life, replacement and depreciation of dairy cows

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Abstract
1. In the Eastern Counties of England, annual wastage from milk recorded dairy herds amounts to 29·3 % of the number of cows at the beginning of the year.2. Average length of productive herd life in milk recorded herds is 3·4 years.3. Average length of total productive life in milk recorded herds is probably a little more than 4 years. Average length of total productive life in all herds is probably longer, and may be of the order of 5 years.4. Deaths of cows are equivalent to 10·4% of the total wastage, and to a mortality rate of 3·0% of the number of cows at the beginning of the year.5. During the three-year period 1934–5 to 1936–7, cows leaving the herd realized an average of £10. 10s. 6d. per head. The average market value placed upon heifers when they entered the milking herd was £20. 14s. per head, while cows for replacement purposes cost an average of £22. 5s. per head.6. Of all replacements, 67·7 % are heifers, but not all of these are home-bred. In annual valuations, 49·0 % of cows are described as homebred, 50·6% as purchased and 0·4% as unknown.