Lipid Metabolism Effects in Cats Fed Diets Varying in Medium Chain Fatty Acids and Linoleic Acid Concentrations
Medium chain triglycerides (MCT) containing fatty acids of 6 to 12 carbons are found in ingredients such as coconut oil and milk byproducts. They are readily absorbed and efficiently metabolized in mitochondria. However, in dogs and cats, some studies show that ca. 22% Metabolic Energy (ME) caused diet aversion, especially when enriched in caprylic acid (C8:0). In dogs, 11%ME MCT showed no effects on food intake, but cats have not been evaluated at this concentration. Thus, we hypothesized feeding cats with 11%ME MCT does not cause diet aversion. The objective of this study was to evaluate a diet containing increased MCT by substituting a portion of the safflower oil containing dietary linoleic acid (LA) with coconut oil. The high MCT diet (HMCT) contained 11.4%ME MCT and 4.3%ME LA (29.9%ME protein, 32.3%ME NFE, 37.8%ME fat) while the low MCT diet (LMCT) contained 4.3%ME MCT and 14.5%ME LA (29.8%ME protein, 29.4%ME NFE, 40.7%ME fat). Nineteen adult female cats were separated into two groups (LMCT, n=9; HMCT, n=10). The cats had been fed a pre-experimental diet (PED) containing no MCT, 5.3%ME LA , and 27% ME total fat for 30 days. Test diets were fed for 9 weeks using week 1 as a transition period. Cats were initially fed according to their metabolic body weights (100*W0.67) and water offered ad libitum. Daily consumption records, weekly body weights (BW) and body condition scores (BCS, 1 to 9) were used to adjust amounts fed and to calculate the daily metabolic energy factors for each cat so that an ideal BCS of 5 was maintained. Blood samples (7ml in EDTA) were taken after overnight fasting via saphenous vein at d 0, 14, 28 and 56 to measure plasma triglycerides (TG), total cholesterol (TC), lipoprotein distribution (LP) and lecithin cholesterol acyl transferase (LCAT). Repeated measures analyses (SAS, Mixed Models Procedure) and Tukey (α=0.05) multiple comparisons were performed. A significant time effect was observed on food consumption, BW, BCS and metabolic factor reflecting the previous PED diet. A diet effect on plasma TG revealed a 28% increase (p=0.0234) with the HMCT diet. However, no diet effects were seen in TC, LP or LCAT activity. Time effects were observed in which TC increased on d 14 and again d 28 but returned back to the d 14 level at d 56 (p=0.0001), LCAT increased at d 14, only. All LP (β, pre-β and α) in both diets reached peak values at d 28 (p=0,0001) consistent with elevation of TC. No diet differences were seen in food intake, metabolic factor, and BW demonstrating that 11%ME MCT does not produce aversion in cats. The TC increase was likely the result of increased dietary fat content of the test diets. A modest increase of plasma TG occurred with HMCT but it was within normal limits. Thus, it is feasible to formulate feline diets containing MCT without diet refusal. Such diets may be useful in both normal cats and those with fat malabsorption syndromes.