Dietary trans fatty acid isomers differ in their effects on mammary lipid metabolism as well as lipogenic gene expression in lactating mice.

The biological activities and mechanisms of action of individual transoctadecenoic acids (trans-18:1 FA) have not been completely elucidated. We examined the effects of several individual trans-18:1 FA isomers and trans-10, cis-12 conjugated linoleic acid (CLA) on fat synthesis, and expression of lipogenic genes in mammary and liver tissue in lactating mice. From d 6 to 10 postpartum, 30 lactating C57BL/6J mice were randomly assigned to either a control (CTR) diet containing 20 g/kg oleic acid or diets in which the oleic acid was either completely replaced by partially hydrogenated vegetable oil (PHVO), trans-7 18:1 (T7), trans-9 18:1 (T9), or trans-11 18:1 (T11) or partially replaced with 6.

Changes in milk fat in response to dietary supplementation with calcium salts of trans-18:1 or conjugated linoleic fatty acids in lactating dairy cows.

Milk fat was investigated in lactating dairy cows fed diets supplemented with Ca salts of trans fatty acids (Ca-tFA) or Ca salts of conjugated linoleic acids (Ca-CLA). Forty-five Holstein cows (115 days in milk) were fed a control diet (51% forage; dry matter basis) supplemented with 400 g of EnerG II (Ca salts of palm oil fatty acids) for 2 wk; subsequently, 5 groups of 9 cows each were assigned for 4 wk to the control diet or diets containing 100 g of Ca-CLA or 100, 200, or 400 g of Ca-tFA in a randomized block design. Treatments had no effect on dry matter intake, milk production, protein, lactose, or somatic cell count.

Duodenal and milk trans octadecenoic acid and conjugated linoleic acid (CLA) isomers indicate that postabsorptive synthesis is the predominant source of cis-9-containing CLA in lactating dairy cows.

Duodenal and milk samples obtained from lactating cows in a previous study were analyzed to compare the content and isomer distribution of conjugated linoleic acids (CLA) and trans-18:1 fatty acids (tFA). Four diets containing either low [25 g/100 g dry matter (DM)] or high (60 g/100 g DM) forage were fed with or without 2% added buffer to four multiparous Holstein dairy cows in a 2 x 2 factorial, 4 x 4 Latin square design with 3-wk experimental periods. Duodenal flows of CLA were low (1.

Mammary lipogenic enzyme activity, trans fatty acids and conjugated linoleic acids are altered in lactating dairy cows fed a milk fat-depressing diet.

The objectives of the present study were to examine the effect of a milk fat-depressing (MFD) diet on: 1) the activity of mammary acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS), 2) ACC mRNA relative abundance and 3) distributions of conjugated linoleic acids (CLA) and trans-18:1 fatty acids (tFA) in milk fat. Twelve lactating Holstein cows were used in a single reversal design. Two diets were fed: a control diet (60:40% forage/concentrate) and an MFD diet (25:70% forage/concentrate, supplemented with 5% soybean oil).