The effects of a prolonged undernutrition on serum lipids and fatty acid composition of reindeer calves during winter and spring.

We examined the effects of undernutrition on lipid metabolism in reindeer (<1 year) during mid-winter and spring, with particular focus on the proportions of polyunsaturated fatty acids (PUFAs) in major serum lipids. The reindeer (n=8) were fed their winter feed, lichen, ad libitum for 5 weeks, followed by 40% restriction of energy for 8 weeks and refeeding to normal for 6 weeks. The concentrations of major serum lipids, cholesterol and phospholipids decreased significantly during the ad libitum period (by 50 and 44%, respectively). The proportion of major PUFA, linoleic acid in serum cholesteryl esters, decreased from 48.2 to 38.4% during the ad libitum period (P < 0.01), and to 29.2% during the restriction period (P < 0.001). The proportion of linoleic acid in phospholipids decreased from 27.9 to 15.6% during the ad libitum period (P < 0. 001), and to 13.0% during the restriction (P < 0.01). Also alpha-linolenic acid in the major lipids decreased significantly during the ad libitum and restriction periods. The decreases in the major lipids and linoleic acid were reversed during the refeeding. The control group (n=8) which was fed high-quality concentrates ad libitum gained weight most of the spring but showed similar although slower decreases in the major serum lipids and PUFAs than the lichen group. Our results indicate that feeding reindeer on lichen during winter leads to the retardation of growth and reductions in major serum lipids and their principal C18-PUFA proportions. The decreased proportions of the principal PUFAs most probably reflect their low dietary intake but may have been modified also by seasonal factors.