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A Comparison of some suggested measures of persistency of milk yield in dairy cows

Published online by Cambridge University Press:  02 September 2010

Ove Madsen
Ove Madsen
Affiliation:
Institute of Animal Science, Veterinary and Agricultural University, Copenhagen, Denmark
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Summary

Five measures of persistency of milk yield were compared by means of apparent heritabilities and repeatabilities using 598 first lactation records from the Danish progeny testing stations and 354 records of all parities from Red Danish cows at a state experimental farm. Unbiased estimates of heritabilities could not be obtained because of common environmental effects. Results indicate that measures of persistency giving equal weight to single milk records are superior to measures giving different weight to single records.

Correlations between persistency, expressed as the absolute decrease of yield, and maximum daily yield were —0·46 to —0·52 (phenotypic) and —0·22 (genetic). Correlations between persistency and 305-day yield were —0·06 to —0·10 (phenotypic) and 0·02 (genetic).Correlations between persistency, expressed as the decrease of yield relative to level of yield in early lactation, and maximum daily yield were —0·06 to —0·13 (phenotypic) and 0·17 to 0·42 (genetic). Correlations between the measure of persistency and 305-day yield were 0·12 to 0·45 (phenotypic) and 0·45 to 0·69 (genetic).

Type
Research Article
Information
Animal Production , Volume 20 , Issue 2 , April 1975 , pp. 191 - 197
Copyright
Copyright © British Society of Animal Science 1975

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References

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