Uptake and Utilization of Trans Octadecenoic Acids in Lactating Dairy Cows

Abstract

Trans fatty acids (FA) arise in ruminant-derived foods as a consequence of rumen biohydrogenation and are of interest because of their biological effects and potential role in chronic human diseases. Our objective was to compare 2 trans FA, elaidic acid (EA; trans-9 18:1) and vaccenic acid (VA; trans-11 18:1), with oleic acid (OA; cis-9 18:1) relative to plasma lipid transport and mammary utilization for milk fat synthesis. Three ruminally cannulated, Holstein dairy cows, 259 +/- 6 DIM (mean +/- SEM), were randomly assigned in a 3 x 3 Latin square design. Treatments were a 4-d abomasal infusion of 1) OA (45.5 g/d), 2) EA (41.7 g/d), and 3) VA (41.4 g/d). Milk samples were collected at each milking and blood samples were collected at the start and end of each treatment period. The proportions of total plasma FA associated with each plasma lipid fraction at baseline (pretreatment) were 62.6 +/- 0.6% phospholipids, 26.1 +/- 0.6% cholesterol esters, 9.8 +/- 0.4% triglycerides, and 1.5 +/- 0.1% nonesterified fatty acids; these values were unaffected by treatment. There were striking differences in the FA composition of the individual plasma lipid fractions and in the distribution of specific 18-carbon FA among the lipid fractions. Infusion of treatment isomers caused their specific increase in the various plasma lipid fractions but had no effect on milk production variables, including milk fat yield and content. Transfer efficiency of infused OA, EA, and VA to milk fat averaged 65.5 +/- 3.0%, 59.7 +/- 1.5%, and 54.3 +/- 0.6%, respectively. For the VA infusion, 24.6 +/- 1.1% of the transfer was accounted for by the increased yield of cis-9, trans-11 conjugated linoleic acid in milk fat, consistent with its endogenous synthesis from VA via the mammary enzyme Delta(9)-desaturase. Notably, linoleic acid (18:2n-6) and linolenic acid (18:3n-3) accounted for 47.7% of total plasma FA, but only 2.6% of FA in milk. Overall, results demonstrate clear differences in plasma transport and mammary uptake and utilization of 18-carbon FA, and these relate to the location, orientation, and number of double bonds.

Role of trans fatty acids in the nutritional regulation of mammary lipogenesis in ruminants

“…Studies involving incubations with rat liver microsomes demonstrated that isomers of trans 18:1 with double bonds at D4 to 7 and D11 to 15 but not D8 to 10 can serve as substrates for SCD in vitro with the extent of conversion being dependent on double-bond position (Mahfouz et al, 1980;Pollard et al, 1980) with the implication that trans-8 18:1, trans-9 18:1 and trans-10 18:1 are not desaturated in the ruminant mammary gland. Although post-ruminal infusions of trans-9 18:1 (Rindsig and Schultz, 1974;Tyburczy et al, 2008) have been shown to have no effect on lipogenesis in the lactating cow, under the specified conditions of these experiments the supply of 18:0 at the mammary gland remained unchanged, and therefore these observations do not provide a rigorous test of the possible role of lowered milk fat fluidity in the etiology of diet-induced MFD. Short-term abomasal infusions of sterculic oil (Griinari et al, 2000;Corl et al, 2001;Kay et al, 2004), trans-9, trans-11 CLA (Perfield et al, 2007) and trans-10, trans-12 CLA (Saebø et al, 2005b;Perfield et al, 2006) as well as administration of Co-EDTA in the rumen (Shingfield et al, 2006b and Figure 6 Structural features of trans fatty acids known to be associated with anti-lipogenic activity in a range of biological models.…”

Effect of incremental amounts of camelina oil on milk fatty acid composition in lactating cows fed diets based on a mixture of grass and red clover silage and concentrates containing camelina expeller

“…Trans-11 18:1 absorbed in the small intestine is preferentially incorporated into plasma triacylglycerols (Tyburczy et al, 2008;Halmemies-Beauchet-Filleau et al, 2013a) that serve as a substrate for milk fat synthesis (Shingfield et al, 2010). Such a mechanism explains the relatively high apparent transfer from the gut into milk and increases in milk fat trans-11 18:1 and cis-9,trans-11 CLA concentrations to increases in postruminal trans-11 18:1 supply (Tyburczy et al, 2008;Halmemies-Beauchet-Filleau et al, 2013a).…”

“…Such a mechanism explains the relatively high apparent transfer from the gut into milk and increases in milk fat trans-11 18:1 and cis-9,trans-11 CLA concentrations to increases in postruminal trans-11 18:1 supply (Tyburczy et al, 2008;Halmemies-Beauchet-Filleau et al, 2013a). Milk fat total CLA concentration typically varies between 0.3 and 0.5 g/100 g of total FA (Lindmark-Månsson, 2008), but on diets supplemented with fish oil or high amounts of plant oil, enrichment of CLA can approach 3.6 g/100 g of total FA .…”

Incremental amounts of ground flaxseed decrease milk yield but increase n-3 fatty acids and conjugated linoleic acids in dairy cows fed high-forage diets1

“…According to Shingfield and Wallace (2014), unsaturated FA with chain lengths >18-C are susceptible to extensive ruminal biohydrogenation. In addition to ruminal biohydrogenation, n-3 FA are extensively confined to plasma cholesterol ester and phospholipids (Tyburczy et al, 2008), which are poorly taken up by the mammary gland (Offer et al, 2001).…”