Dietary conjugated linoleic acids alter adipose tissue and milk lipids of pregnant and lactating sows

Conjugated linoleic acids (CLA) have been shown to affect fatty acid synthe sis in various tissues. The objective of the study was to compare the effec t of a commercial source of CLA with a linoleic acid-enriched oil (LA), sup plied to 12 multiparous sows during gestation and lactation, on adipose tis sue and milk fatty acid composition. The CLA isomers detected in the CLA oi l were (in order of magnitude) c9,t11; t10,c12; c9,c11; t9,t11/t10,t12 and c10,c12 and amounted to 58.9 g/100 g fat. Biopsies were taken from the back fat on d 7 and 97 of gestation and milk samples were collected on d 2, 9, 1 6 and 23 after farrowing. Collection of colostrum and mature milk samples t ook place at 1100 h for sows who farrowed in the morning or at 1500 h for t hose who farrowed in the afternoon. All major CLA isomers in the supplement were transferred to the tissue and milk fat and, compared with the LA grou p, significantly increased saturated fatty acid and decreased monounsaturat ed fatty acid levels in the tissue and milk. These findings suggest a disti nct involvement of CLA in the de novo fatty acid synthesis and desaturation process in the adipose tissue and mammary gland. Estimated transfer effici ency of dietary CLA isomers was 41-52% for the backfat and 55-69% for the m ature milk. The incorporation and uptake efficiency seemed to be selective with the highest values found for c9,t11-CLA. Overall, dietary CLA suppleme ntation of sows during gestation and lactation markedly altered backfat and milk fatty acid composition.