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A note on the estimation of environmental effects on lactation curves

Published online by Cambridge University Press:  02 September 2010

E. Strandberg
Affiliation:
Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, PO Box 7023, S-75007 Uppsala, Sweden
C. Lundberg
Affiliation:
Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, PO Box 7023, S-75007 Uppsala, Sweden
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Abstract

A method was suggested that attempts to distinguish between the underlying lactation curve, the effect of season of production, and the effect of time after conception. The composite function was shown to give a better fit than an incomplete gamma function. The estimated parameters of the underlying lactation curve were unaffected by season of calving whereas the parameters of the gamma function were not. Pregnancy started to affect yield 160 days after conception by -0·1 kg/day. The difference between the best season of production (May) and the worst (November) was around 5 kg.

Type
Notes
Copyright
Copyright © British Society of Animal Science 1991

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References

Congleton, W. R. and Everett, R. W. 1980. Error and bias in using the incomplete gamma function to describe lactation curves. Journal of Dairy Science 63:101108.Google Scholar
Danell, B. 1982. Studies on lacation yield and individual test-day yields of Swedish dairy cows. I. Environmental influence and development of adjustment factors. Ada Agrkulturae Scandinavica 32: 6581.Google Scholar
Grossman, M. and Koops, W. J. 1988. Multiphasic analysis of lactation curves in dairy cattle, journal of Dairy Science 71: 15981608.Google Scholar
Koops, W. J. 1986. Multiphasic growth curve analysis. Growth 50:169177.Google ScholarPubMed
Louca, A. and Legates, J. E. 1968. Production losses in dairy cattle due to days open. Journal of Dairy Science 51: 573583.Google Scholar
Olds, D., Cooper, T. and Thrift, F. A. 1979. Relationships between milk yield and fertility in dairy cattle. Journal of Dairy Science 62:11401144.CrossRefGoogle ScholarPubMed
Statistical Analysis Systems Institute. 1985. SAS user's guide: statistics, version 5 edition. SAS Institute Cary, NC.Google Scholar
Wood, P. D. P. 1967. Algebraic model of the lactation curve in cattle. Nature, London 216:164165.CrossRefGoogle Scholar
Wood, P. D. P. 1969. Factors affecting the shape of the lactation curve in cattle. Animal Production 11: 307316.Google Scholar
Wood, P. D. P. 1976. Algebraic models of the lactation curves for milk, fat and protein production, with estimates of seasonal variation. Animal Production 22:3540.Google Scholar