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3.4 Lactation Curves

Published online by Cambridge University Press:  27 February 2018

P. D. P. Wood
P. D. P. Wood*
Affiliation:
Milk Marketing Board, Thames Ditton, Surrey
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An algebraic description of the lactation curve is a useful component of any model of the day-to-day production of lactating animals. Observation and common sense suggest that such a function should rise to a peak early in lactation and decline thereafter but simpler models have been used. Ostergaard (1979), for example, used a linear model to study strategies for concentrate feeding to obtain optimum feeding levels in high yielding dairy cows. His model was

where y (t) was the yield in week t and a and b were the usual linear regression coefficients. The error term is omitted here and elsewhere for clarity. Gaines (1927) used the decay function

where A and k are the constants fitted to log y (t).

These models, one linear, the other exponential, peak in Week 1 and require only two parameters. In this paper, more sophisticated functions are described and compared.

A lactation curve is assumed to contain two components, one of which is the intrinsic biological drive to produce milk and the other is an environmental constraint upon it. The algebra may be justified by biological argument according to the skill and the leanings of the modeller.

Type
3. Model Building
Information
BSAP Occasional Publication , Volume 5 , 1981 , pp. 111 - 114
Copyright
Copyright © British Society of Animal Production 1981

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References

REFERENCES

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