Relative bioavailability of L-ascorbyl-2-polyphosphate in broiler chickens

Broiler chick diets and drinking water were supplemented with two sources of vitamin C: crystalline L-ascorbic acid (AsA) or L-ascorbyl-2-polyphosphate (APP) to provide 0, 25, 50, 100, 200, 400, 800, 1,600, and 3,200 ppm (mg/kg) AsA. The bioavailability of APP relative to AsA, as estimated by the change in plasma AsA concentration, was evaluated during 24-h periods of supplementation. When provided in the feed, no differences in dietary AsA content were attributed to vitamin source. In contrast, APP administration at 25 and 50 ppm, resulted in higher (P < .001) AsA values in drinking water when compared with AsA supplementation. Plasma AsA values were elevated (P < .05) above baseline when either AsA or APP were supplemented in the feed or water at a level of 400 ppm or greater. Plasma AsA concentrations, following supplementation of the diets, were higher (P < .05) in AsA-treated (800 ppm) chicks when compared with APP-supplemented chicks. During water supplementation, AsA (800 ppm) and APP (3,200 ppm) administration resulted in higher plasma AsA values when compared with their alternate vitamin source. At all other levels of water supplementation, no differences in plasma AsA were associated with vitamin source. The absence of a consistent difference in plasma AsA, relative to vitamin source, suggests that the isolated differences observed may be due to chance. It was concluded that APP was of similar bioavailability to that of AsA, as estimated by the ability to elevate plasma AsA concentrations in broiler chicks.