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Factors affecting the ethanol stability of bovine skim milk

VII. Lactational and compositional effects

Published online by Cambridge University Press:  01 June 2009

David S. Horne ,
Thomas G. Parker ,
William J. Donnelly  and
D. Thomas Davies
David S. Horne
Affiliation:
Hannah Research Institute, Ayr KA6 5HL, UK
Thomas G. Parker
Affiliation:
Hannah Research Institute, Ayr KA6 5HL, UK
William J. Donnelly
Affiliation:
Agricultural Institute, Moorepark Research Centre, Fermoy, Co. Cork, Irish Republic
D. Thomas Davies
Affiliation:
Agricultural Institute, Moorepark Research Centre, Fermoy, Co. Cork, Irish Republic
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Summary

Milk samples from three groups of cows were taken at frequent intervals throughout lactation following autumn-, winter- or spring-calving. The ethanol (EtOH) stability/pH profile was determined for each sample and its characteristic parameters calculated. The lactational trends in these parameters were examined. Asymptotic maximum EtOH stability (Smax) was low in early lactation but rose rapidly to a value which showed no further lactational trends. Asymptotic minimum stability (Smin) for samples from autumn- and winter-calving cows showed a decrease which could be associated with the transition to summer grazing but no obvious lactational effects. The slope parameter increased slowly during lactation. The profile pK value decreased in early lactation, but thereafter increased throughout lactation giving the most obvious effect observed in direct measurement, namely an alkaline shift in the profile as lactation progressed. The EtOH stability calculated at a fixed pH of 6·6 passed through a maximum, characteristic for each cow, in the first weeks of lactation but declined steadily thereafter. This behaviour mirrors the lactational behaviour of the soluble salt balance ratio calculated from the original data of White & Davies (1958).

Type
Original Articles
Information
Journal of Dairy Research , Volume 53 , Issue 3 , August 1986 , pp. 407 - 417
Copyright
Copyright © Proprietors of Journal of Dairy Research 1986

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References

REFERENCES

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