Studies on Vitamin E Deficiency in Chicks

Abstract

The symptoms of vitamin E deficiency in chicks—exudative diathesis and encephalomalacia—can be accelerated or suppressed by dietary changes which are unrelated to the vitamin E content of the diet. Purified diets containing no added fat rarely produce exudates and never induce encephalomalacia. Both symptoms are accelerated by highly unsaturated fatty acids. The fatty acids from cod liver oil, lard and linseed oil and commercial unsaturated C₂₀ acids at a level of about 5% in the diet produce exudates as the main symptom, whereas fatty acids from hog liver favor the appearance of encephalomalacia. Oleic acid and thoroughly rancid cod liver oil are ineffective in producing either symptom. A certain protein-carbohydrate ratio is optimal for the appearance of exudates, and the tendency to exudates is further enhanced by those inorganic salts which tend to accumulate in the extracellular fluid. High lard (30%) favors encephalomalacia more than exudates when the carbohydrate-protein ratio is low. Inositol (1.5%) counteracts both symptoms. Lipocaic (2%) counteracts only exudative diathesis. Cholesterol (1%) hastens exudates when the diet contains 5% cod liver oil and a low salt content, and counteracts encephalomalacia when the diet contains 30% lard. The iodine value of body phosphatides is influenced by dietary fat independently of the presence of vitamin E. It is believed that the effect of the different fatty acids consists in a damage of tissue rather than in a general destruction of vitamin E, and that inositol, lipocaic and cholesterol do not act simply through a general pro- or anti-oxidant effect. The response of different species of animals to diets which produce exudates or encephalomalacia in chicks is discussed.