INFLUENCE OF DIETARY FAT LEVEL ON GROWTH AND BODY COMPOSITION OF THE NEONATAL PIG

Abstract

Four Yorkshire piglets, from each of 18 litters, were randomly allotted within litters, to four treatment groups 12 h after birth. Group 1 (Control) continued to be suckled by sows; the remaining piglets were reared artificially on a semi-synthetic liquid diet containing either 25% soybean oil (SBO) (group 2) or 3% SBO plus 22% lactose (groups 3 and 4). At 7, 14 and 21 days of age, 24 pigs from six litters were killed. Piglets on the 25% SBO diet grew faster (P < 0.05) than those on the 3% SBO diet while the growth rate of the suckled piglets tended to be between the growth rates of those on the two SBO diets. Body fat content increased with the fat content in the diet and with age. The protein:fat ratio was greatest in the piglets on the 3% SBO diet and least in the suckled piglets. The fatty acid composition of backfat changed, primarily during the first week of life, towards that of the dietary fat. This was evident even in piglets on the low fat-high carbohydrate (3% SBO) diet. The composition of the fat deposited in piglets on the 3% SBO group indicated preferential utilization of essential fatty acids and little de novo synthesis of fatty acids. The amount and type of fat deposited by piglets fed the 3% SBO diet, together with preliminary evidence of low incorporation of radioactivity from (U14C) glucose with adipose tissue fatty acids in vivo, suggest that the de novo fatty acid biosynthesis in adipose tissue of piglets is not as high as previously reported (Mersmann et al. 1973). Key words: Neonatal pigs, fat deposition, fatty acid biosynthesis.