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A retrospective analysis of culling in a large AI stud
Published online by Cambridge University Press: 02 September 2010
Summary
Of 335 British Friesian bulls at AI centres progeny tested during the period 1960–65, 19% were retained for further use in the programme following selection.
A time trend towards more intense selection was observed, from an initial selection rate of 1 in 3 to a final rate of 1 in 7. This appeared to involve increased culling for both daughter type and daughter production.
At all stages of the programme approximately 50% of the selection practised was directed towards attributes other than milk yield.
A comparison of the mean contemporary comparison (c.c.) values of the selected bulls with the values obtained following selection solely for milk yield indicated that the inclusion of daughter type as a criterion of selection reduced the c.c. value of the stud by approximately 33%.
A drastic reduction in the c.c. value of the selected bulls was observed to coincide with the appearance of subsequent groups of daughters in the sire proofs.
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- Copyright © British Society of Animal Science 1975
References
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