Effect of Dietary γ-Linolenic Acid-Enriched Oil on Backfat Thickness and Liver Fatty Acid Degrading Enzyme Activity in Growing Pigs

Abstract

We have previously reported that dietary γ-linolenic acid-enriched oil (GLA oil) reduces body fat content and increases liver enzyme activities related to fatty acid β-oxidation in rats. In this experiment, the effects of dietary GLA oil on backfat thickness and liver fatty acid degrading enzyme activities in growing pigs were investigated. Thirteen castrated pigs (Landrace×Large White×Duroc) weighing about 69kg were used. Pigs were given 90g of GLA oil or soybean oil (control) daily and free access to the basal diet during the experimental period of 6 weeks. The backfat thickness was measured weekly with an ultrasonic instrument at the half site of body length. Body weight gain, feed intake and feed efficiency in the GLA oil group were similar with the control group. The gain of backfat thickness in both groups increased almost linearly as time passed. However, that in the GLA oil group was significantly lower than in the control group on the 6th week. The activity of liver carnitine palmitoyltransferase in the GLA oil group, which is the rate-limiting enzyme of mitochondrial fatty acid β-oxidation, was higher than in the control group. Furthermore, liver peroxisomal β-oxidation activity in the GLA oil group was significantly higher than in the control group. These results suggested that dietary GLA oil reduces the gain of backfat thickness and increases the activities of liver fatty acid degrading enzymes.