ARTIFICIAL REARING OF PIGS .7. MEDIUM CHAIN TRIGLYCERIDES AS A DIETARY SOURCE OF ENERGY AND THEIR EFFECT ON LIVE-WEIGHT GAIN, FEED-GAIN RATIO, CARCASS COMPOSITION AND BLOOD-LIPIDS

1. Pigs were weaned at 2 d of age and fed on a milk substitute at hourly intervals. They were slaughtered at 28 d of age. 2. The diets contained 730 g dried skim-milk and 270 g fat/kg dry matter (DM). Three diets were compared in which the fat was supplied as soya-bean oil (SO) (diet A), equal amounts of SO and medium-chain triglyceride (MCT) (diet H), or 246 g MCT and 24 g SO (diet I)/kg DM. In the latter diet, SO ensured that the diet had an adequate content of essential fatty acids. 3. Growth rate (2–28 d of age) was reduced (P < 0.05) by the high-MCT diet (diet I) compared with the medium-MCT diet (diet H), but in comparison with diet A, the differences were not significant (P > 0.05). The feed: gain ratio (g DM consumed/g live-weight gain) was not affected by the type of dietary lipid. 4. Diet I increased the proportion of crude protein (nitrogen × 6.25) (g/kg wet weight) in the carcass but did not increase N retention (g/d per kg live weight). The proportion of fat in the carcass was reduced, particularly by diet I (P < 0.001), and was inversely related to an increase mainly in the water content, and to a lesser extent, in the crude protein content of the carcass. The liver weight (g/kg live wt) was greatly increased by MCT (P < 0.01 or P < 0.001). 5. Approximately 20, 44 and 80% of the fatty acids in the carcass of pigs on the SO, diet H and diet I respectively could not have been derived from direct deposition of the dietary fatty acids, but rather by de novo synthesis from carbohydrate or elongation of shorter-chain fatty acids. MCT increased the concentrations in the blood, taken 1 h after feeding, of total lipid, phospholipid, cholesterol and cholesterol ester, indicating incomplete oxidation of the caprylic and caprylic and capric acids in MCT by the liver, and their incorporation, after chain elongation, into plasma lipids. © 1979, The Nutrition Society. All rights reserved.