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A note on the relationship between live weight and the incidence of oestrus in Hereford heifers

Published online by Cambridge University Press:  02 September 2010

R. D. H. Cohen
Affiliation:
Department of Agriculture, Agricultural Research Station, Grafton, New South Wales 2460, Australia
D. L. Garden
Affiliation:
Department of Agriculture, Agricultural Research Station, Grafton, New South Wales 2460, Australia
J. P. Langlands
Affiliation:
Division of Animal Production, Commonwealth Scientific and Industrial Research Organisation, Pastoral Research Laboratory, Armidale, New South Wales 2350, Australia
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Abstract

The incidence of oestrus in 603 Hereford heifers with a mean age of 545 days (range 515 to 575) was related to live weight (range 130 to 376 kg). Observations were ranked in order of ascending live weight and the percentage of heifers showing oestrus was calculated for consecutive 10 kg increments in live weight from 130 to 380 kg. The percentage showing oestrus was subjected to the probit transformation (Y, probit units) and was then related to live weight (X, kg):

It was predicted that 50% of the heifers showed oestrus at 231 ± 1 kg, and that 5% and 95% showed oestrus at 187 and 280 kg respectively.

Type
Research Article
Copyright
Copyright © British Society of Animal Science 1980

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References

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