A high dietary lipid intake during pregnancy and lactation enhances mammary gland lipid uptake and lipoprotein lipase activity in rats

Rats fed a diet with high fat concentration produce larger amounts of milk with a higher lipid concentration than rats fed a lower fat diet. This inve stigation was designed to study the relationship between dietary fat intake , mammary gland lipid uptake and lipogenesis in rat dams fed, during pregna ncy and lactation, one of two purified diets, with equal energy density, co ntaining 2.5 (LL) or 20 g fat/100 g diet (HL). Milk lipid concentration and fatty acid composition were determined at d: 14 of lactation. Mammary glan d lipogenesis, lipoprotein lipase (LPL) activity and the uptake of [1-C-14] triolein by the mammary gland and its transfer to the pups was measured. Th e intestinal absorption of oral C-14-lipid,(CO2)-C-14 production and the am ount of C-14-lipid transferred to the pups (milk clot + pups carcass) were significantly higher in the HL group than in the LL group (P < 0.05). Mamma ry gland lipogenesis was 75% lower and LPL: activity was 30% higher in the HL group (P ( 0.05). Medium-chain fatty acids (C6-C14) excretion was 46% lo wer and that of long-chain fatty acids was 142% (P < 0.001) higher in the H L group than in the LL group. The higher milk lipid excretion in the rats f ed a high-fat diet resulted from a larger uptake of dietary lipid by the ma mmary gland, indicated by a larger transfer of C-14-lipid to the pups and b y a higher LPL activity in the mammary gland.