Vitamin e and Polyunsaturated Fatty Acids in Swedish Feedstuffs for Cattle

The total concentration of vitamin E, the relative proportions of its isomers, and the concentrations of polyunsaturated fatty acids (PUFA) have been measured in fresh grass, grass silage and hay, and in barley and oats grown in Sweden. The concentration of vitamin e was much higher in fresh grass and grass silage than in hay or grain, and there were large differences between the proportions of the isomers of vitamin e present in the different feedstuffs. No tocotrienols were detectable in the roughages, but between 67 and 79 weight per cent of the total vitamin e content of oats and barley consisted of tocotrienols—mostly α-tocotrienol. More than 95% of the total biological vitamin e activity of roughage was due to α-tocopherol, whereas between one third and one half of the vitamin e activity of grain was due to α-tocotrienol. The calculated relative biopotencies of the total vitamin e in grass, grass silage, hay, barley and oats were 125, 127, 110, 39 and 67% respectively. Roughages contained 1.5–3.5 times more linolenic acid than linoleic acid, whereas barley contained 9 times and oats contained 27 times more linoleic acid than linolenic acid. Fresh grass, grass silage, barley and oats all contained slightly more than 20 mg of biologically active vitamin e per g of linolenic acid. Hay contained only 8.1 mg per g after 7–10 months' storage.