Studies on pigs reared on diets low in tocopherol and essential fatty acids.

Although the role of tocopherol in the nutrition of small laboratory animals has been extensively investigated, relatively little attention has been given to the requirement of larger domestic animals. Evidence is conflicting about any function or effect tocopherol may have on pig nutrition. Bratzler, Loosli, Krukovsky & Maynard (1950) found that tocopherol supplementation of a diet low in tocopherol and fat markedly affected the composition of body fats by increasing the content of oleic acid. Hove & Seibold (1955) showed that tocopherol supplementation of diets containing 6 yo lard and 2 % cod-liver oil increased the content of polyunsaturated fatty acids in muscle and liver. Garton, Duncan, Madsen, Shanks & Beattie (1958) and Duncan, Garton, McDonald & Smith (1960) failed to confirm these findings. That tocopherol exerts a protective effect on the oxidation of body lipids of rats has been shown by Barnes, Lundberg, Hanson & Burr (1943). For the pig, however, evidence is conflicting. Watts, Cunha & Major (1946) found that supplementing purified rations with tocopherol increased only slightly the stability of pig fat and had no effect when natural diets were supplemented. Carpenter & Lundberg (1949), however, reported that the induction period, as measured by an oxygen-absorption method, of body fat from pigs fed on a partly purified diet supplemented with tocopherol was longer than that found in the fats from unsupplemented controls. The experiments reported below were designed to investigate the role of tocopherol in the nutrition of the pig up to 200 lb live weight, special attention being paid to any effect tocopherol might have on the composition and stability of the body lipids. In nearly all the previous experiments reported in the literature, the piglets used were of normal weaning weight (35-45 lb) in which considerable storage of tocopherol could have already occurred. To prevent the accumulation of too large a reserve of tocopherol, the piglets were weaned within 3 weeks of birth, when they weighed about 10 lb. The basal diet used, besides being low in tocopherol, was also low in fat to prevent undue alteration in the composition of the body fat and to prevent the complicating effect that fat has on the requirement for tocopherol.