Effects of conjugated linoleic acid and sunflower seed on fatty acid composition of cow's milk. (Wirkung konjugierter Linolsäuren und Sonnenblumensaat auf die Fettsäurezusammensetzung in Kuhmilch).

Publikations-Art

Kongressbeitrag

Autoren

Hoffmann A., Steingaß H. and Drochner W.

Erscheinungsjahr

2008

Veröffentlicht in

Berichte der Gesellschaft für Ernährungsphysiologie

Herausgeber

Gesellschaft für Ernährungsphysiologie

Verlag

DLG-Verlags-GmbH , Frankfurt/M.

Band/Volume

17/

Serie/Bezeichnung

Proc. Soc. Nutr. Physiol.

ISBN / ISSN / eISSN

978-3-7690-4101-9

Seite (von - bis)

63

Tagungsort

Göttingen

Tagungsdatum

01.04.2008

Schlagworte

cow, Linolsäure, Milch, Sonnenblumensaat, Sunflower

Conjugated linoleic acids (CLA) refer to a group of geometrical and positional isomers of linoleic acid with conjugated double bonds. CLA occurs in different configurations. The two most important and best known isomers are C18:2 cis9 trans11 and C18:2 trans10 cis12. These isomers have been reported to have positive effects on health and production parameters. The aim of the present study was to determine the effects of supplementation of linoleic acid rich oil and the CLA isomer C18:2 t10 c12 in diets of dairy cows on performance and the fatty acid (FA) composition of milk fat with special consideration of CLA and trans fatty acids.Methods: 22 Holstein cows in mid lactation were allocated to three groups (1 x 8, 2 x 7) and were fed a control (C) diet (with sunflower extraction meal), a crushed full fat sunflower seed (SF) diet (5% of DM → 500g of SF oil) and a CLA supplement (0.25% of DM plus sunflower extraction meal) as TMR in a 3 x 3 latin square design. The CLA supplement contained 10% coated C18:2 t10 c12. The TMR was composed (in DM) of 16% corn silage, 26% grass silage, 10% hay and 48% concentrate containing the respective supplements. After 14 days adaptation period, individual feed intake, milk production and milk composition was measured for 10 days. FA composition of milk was analysed by GC using Supelco SP 2380 column (30m) from a bulk milk fat sample collected as aliquots 4 x during the main period.Results: DM intake was not affected by treatment, whereas SF and CLA caused a significant higher milk production (29,4; 32,0; 31,6 [kg/d] for C, SF and CLA diet, respectively). Percent milk fat and protein were significantly lower in SF and CLA diets. Calculation of daily production of individual FA (fat yield x molar proportions, corrected for glycerol content) revealed, that supplementation of SF caused a significant reduction of short and medium chain FA (£C16) in favour of long chain FA (³C 18). In addition, production of C 18:2 c9 t11 and C 18:1 t11 rose about twofold in SF treatment. CLA significantly reduced production of FA £C 16, whereas no change in the produced quantities of FA ³C 18, of CLA and of trans-FA was found. The results are summarized in table 1.Conclusion: SF seed rich in linoleic acid has potential to increase CLA and vaccenic acid (C18:1 t11) in milk fat, which indicates limiting capacities for rumen biohydrogenation and/or desaturation in the mammary gland. In contrast to several reports in the literature, the supplemented CLA isomer C18:2 t10 c12 seems to inhibit milk fat production only through depression of de novo fat synthesis, whereas the integration of long chain FA into milk fat was not affected