Production and clearance of plasma triacylglycerols in ponies fed diets containing either medium‐chain triacylglycerols or soya bean oil

Summary The hypothesis was tested that feeding ponies a diet containing medium‐chain triacylglcyerols (MCT) instead of soya bean oil causes an increase in the production of plasma triacylglycerols, which, under steady‐state conditions, is associated with an increased clearance of triacylglycerols. Six ponies were fed rations containing either MCT or an isoenergetic amount of soya bean oil according to a cross‐over design. The concentration of MCT in the total dietary dry matter was about 13%. When the ponies were fed the diets for 3 weeks, plasma triacylglycerol concentrations were 0.42 ± 0.09 and 0.17 ± 0.03 mmol/l (mean ± SE, n  = 6; p < 0.05) for the MCT and soya bean‐oil treatment, respectively. Plasma triacylglycerol production was assessed using the Triton method and clearance with the use of Intralipid ® infusion. Plasma triacylglycerol production was 2.91 ±  0.88 and 0.50 ± 0.14  μ mol/l·min (means ± SE, n  = 4; p < 0.05) for the diets containing MCT and soya bean oil, respectively. It is suggested that the calculated rates of triacylglycerol production are underestimated, the deviation being greatest when the ponies were fed the ration of soya bean oil. Triacylglycerol clearance rates were calculated on the basis of group mean values for both the fractional clearance rate and the baseline levels of plasma triacylglycerols; the values were 4.28 and 3.52  μ mol/l·min for MCT and soya bean oil feeding, respectively. The mean, absolute clearance rates as based on those found in individual ponies did not show an increase when the diet with MCT was fed. Nevertheless, it is concluded that the data obtained support our hypothesis.