The effect of dietary changes on plasma lipids and lipoproteins of six Labrador retrievers

Six healthy, spayed female Labrador Retrievers (aged 5.5 to 11 years), kept under controlled conditions of exercise and housing, were fed a diet of 15 per cent fat, 24 per cent carbohydrate and 33 per cent protein for two weeks before and between each of three test diets, of differing fat to carbohydrate ratios (A 13:44, B 20:33, C 25:26 fat:carbohydrate gm per cent dry weight) given in a predetermined order for four weeks each. Fasting plasma lipoproteins and total fatty acids were measured weekly. In the fourth week of each test period post-prandial plasma lipoproteins were measured. Diets B and C increased total (P < 0.001) and LDL cholesterol (P < 0.05) whilst diet A increased HDL triglyceride (P < 0.05). Eicosapentaenoic acid (C20:5) increased on diets B and C, and oleic acid (C18:1) on diet A. Post-prandial hypertriglyceridaemia occurred on all diets. Chylomicron clearance was slower on higher fat diets. Relatively small dietary changes produced significant alterations of plasma lipids, lipoproteins and chylomicron clearance.