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Δ9 -desaturase activity in the mammary gland of lactating dairy cows

Published online by Cambridge University Press:  20 November 2017

A.L. Lock  and
P.C. Garnsworthy
A.L. Lock
Affiliation:
The University of Nottingham, Division of Agriculture and Horticulture, Sutton Bonington Campus, Loughborough, Leicestershire, LE12 5RD, UK
P.C. Garnsworthy
Affiliation:
The University of Nottingham, Division of Agriculture and Horticulture, Sutton Bonington Campus, Loughborough, Leicestershire, LE12 5RD, UK
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Extract

The Δ9 -desaturase system (steroyl-CoA desaturase) involves the addition of a cis double bond between carbons 9 and 10 of fatty acids. The conversion of stearic acid (C18:0) to oleic acid (cis-9 C18:1) is the predominant precursor:product of this enzyme system; conversion of saturated fatty acids (SFA) to mono-unsaturated fatty acids (MUFA) is important in determining the fluidity of milk. In previous studies (Lock & Garnsworthy 2001), we have shown that more than 50% of the oleic acid occurring in milk is produced in the mammary gland via Δ9 -desaturase. We also found that the conversion of trans-11 C18:1 to cis-9, trans-11 conjugated linoleic acid (CLA) accounted for ~80% of milk fat CLA. Increasing the activity of Δ9 -desaturase offers the opportunity of increasing the MUFA content of milk, especially oleic acid, while decreasing its SFA content, as well as increasing the CLA content of milk. Lock & Garnsworthy, (2001) also reported that there were significant differences between individual cows with regard to milk fat CLA content. In an earlier study (Lock & Garnsworthy, 2000) we found that the CLA content of milk varied throughout the year, with highest values occurring when cows received fresh pasture. In view of the significant contribution of Δ9 -desaturase to the CLA and MUFA content of milk, the objective of the work reported here was to investigate individual animal and dietary variation in Δ9 -desaturase activity in the mammary gland of lactating dairy cows.

Type
Poster Presentations
Information
Proceedings of the British Society of Animal Science , Volume 2002 , 2002 , pp. 181
Copyright
Copyright © The British Society of Animal Science 2002

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References

Lock, A. L. & Garnsworthy, P. C. (2000). Changes in the conjugated linoleic acid content of milk desaturase from dairy cows throughout the year. In Milk Composition. Occasional Publication No. 25 - British Society of Animal Science (ed. Agnew, R. E., Agnew, A. K. and Fearon, A. M.), pp. 125–129.Google Scholar
Lock, A. L. & Garnsworthy, P. C. (2001). Independent effects of dietary linoleic and linolenic fatty acids on the conjugated linoleic acid content of cows’ milk. Animal Science (in press).Google Scholar