Yang G, Bu DP,Wang JQ, Khas-Erdene, Zhou LY, Loor JJ
Journal of Dairy Science2012,95(10):5821-5830.
Abstract:Increasing the concentration of α-linolenic acid (LNA; 18:3 cis-9,cis-12,cis-15) in blood might affect fatty acid (FA) metabolism in the mammary gland of dairy cows. The objective was to determine the effects of different arterial concentrations of18:3 cis-9,cis-12,cis-15 (18:3n-3) achieved via duodenal infusions with LNA onmammary uptake [assessed via arterial-rectificative venous concentration(AC-RVC) differences], synthesis of FA, and mammary gland FA balance in lactating dairy cows. Four primiparous lactating Chinese Holstein cows fitted with duodenal cannulas were administered 2 treatments in a crossover design:LNA-rich FA infusion at varying concentrations (0, 100, 200, and 300 g/d)versus basal infusate control. Arterial concentration of 18:3n-3 increased quadratically (29.24, 134.1, 218.3, and 219.3mg/L of plasma) as LNA infusion levels increased from 0 to 300 g/d. The mammary extraction rate and uptake of18:3n-3 increased linearly as LNA infusion increased. The AC-RVC difference of total FA and 18:3n-3 increased more rapidly than arterial concentrations with all treatments. Increasing LNA infusion increased linearly the balance of 10:0and 12:0, whereas it decreased linearly the 14:1 and 15:0 balances. Increasing arterial concentration of 18:3n-3 affects uptake and synthesis of FA in the mammary gland of lactating dairy cows. It is also suggested that the use ofAC-RVC difference maybe an acceptable way to investigate mammary gland uptake and synthesis of FA.
Keywords:α-linolenicacid, mammary gland metabolism, uptake, dairy cow