The absorption and metabolism of vitamin E in swine
A series of experiments were designed to study the digestion and metabolism of vitamin E in growing swine. Through the analysis of serum samples of weanling pigs from two swine herds indicated that genetic background had an effect on vitamin E and selenium status. A wide variation was detected in serum alpha-tocopherol (ALPHA) concentration (P <.001), glutathione peroxidase (P <.001) and lactic acid dehydrogenase (P <.01) activity among genetic lines. Within a herd, pigs were reared under similar environment, nutrition and management. The digestibility of dl-alpha-tocopheryl acetate (dl-ACE) and d-alpha-tocopheryl acid succinate (d-SUCC) was efficient and did not differ in 20 to 40 kg pigs fed at 1.0 to 1.4% body wt/day during a 13 day balance study. And, ALPHA produced from ester hydrolysis in the gut was efficiently digested in both esters. Serum ALPHA increased in pigs fed diets containing esters, but no difference was detected between the esters. In a 4 week trial in which pigs were fed at 3% body wt/day, the digestibility of dl-ACE was greater than d-SUCC, and digestibility of ALPHA produced from dl-ACE was lower than ALPHA produced from d-SUCC. Diets contained 22 IU/kg of dl-ACE or d-SUCC. Tissue ALPHA was greater in pigs fed esters than in tissues of pigs fed non-supplemented diets. Internal organs tended to have higher ALPHA concentration than muscles, plasma or bile. There was no difference in plasma or tissue ALPHA between dl-ACE and d-SUCC. Pigs digested a 500 IU dose of dl-ACE as efficiently as the physiological level fed during the trial. Pigs fed dl-ACE tended to reach maximum plasma ALPHA faster and have a lower terminal plasma ALPHA than pigs fed d-SUCC. And, plasma ALPHA tended to decrease faster in pigs fed dl-ACE than in pigs fed d-SUCC. There are differences in vitamin E and selenium status between genetic lines of swine. And, there was a difference in the pattern of digestion between dl-ACE and d-SUCC. dl-ACE was hydrolyzed more efficiently than d-SUCC but d-SUCC resulted in a slower, more sustained increase in plasma ALPHA.