Uptake and Utilization of Trans Octadecenoic Acids During Lactation

Abstract

Trans fatty acids (FA) from industrial sources are associated with adverse human health effects. Trans-9 18:1 is the major trans isomer and this contrasts with ruminant fat where trans-11 18:1 predominates. Our objective was to examine the biological activity of trans-9 18:1 and trans-11 18:1 in relation to cis-9 18:1 in the dairy cow. Holstein cows (n=3) were used in a 3x3 Latin square design, and treatments (>82% purity) were abomasal infusion of 1) trans-9 18:1 (41.7 g/d) 2) trans-11 18:1 (41.4 g/d) and 3) cis-9 18:1 (45.5 g/d). Treatment periods were 4 d and yields of milk and milk components were unaffected by treatment. Transfer efficiency of infused FA to milk fat triglycerides (TG) was 59.1 ± 0.1%, 54.2 ± 0.1% and 54.6 ± 0.3% (means ± SD) for trans-9 18:1, trans-11 18:1 and cis-9 18:1, respectively. Distribution of total plasma FA did not differ among treatments, averaging 60.3 ± 2.2%, 32.1 ± 1.8%, 6.4 ± 0.8% and 1.2 ± 0.3% for phospholipids (PL), cholesterol esters (CE), TG and free fatty acids (FFA), respectively. Plasma content of trans 18:1 FA (% of total FA) was greatest for TG and least for CE. Infusion of cis-9 18:1 resulted in its increase mainly in PL. Infusion of trans-9 18:1 and trans-11 18:1 increased their specific content in PL, TG and FFA fractions, but for trans-11 18:1 the relative increase was much greater in plasma TG and FFA. Results demonstrate differences among octadecenoic FA that impact their unique biological effects.