Utilization of Vitamin a in D I F F E R E N T Carriers by Beef Cattle

N ATURE of the carrier is known to affect efficiency of utilization of vitamin A by several species. For humans, aqueous dispersions of vitamin A have been found superior to oil solutions for maintaining blood levels and promoting growth (Kramer, 1947; Lewis, 1947, 1950; Sobel, 1949; and their respective coworkers). Kagan et al., (1953) reported that both alcohol and ester forms in aqueous dispersion enter the blood more readily than vitamin A in oil. Aqueous forms of vitamin A have shown superior bio-availability to oil forms with dairy calves (Jacobson et al., 1954; Wise et al., 1949), with chicks (Halpern and associates, 1947) and with rats (Popper and Volk, 1948; Volk and Popper, 1950; Lewis and Cohlan, 1950; Sobel et al., 1948). Vitamin A dispersed in gelatin beadlets has been found superior to oil solution for liver storage in rats and for growth and liver storage in chicks (Luther et al., 1952), an observation which was recently confirmed in rats by Briiggemann and Tiews (1956) and in chicks by Ascarelli (1957). Particle size of the vitamin A within the gelatin beadlet affects efficiency of utilization (Luther et al., 1952). It was found that for rats particles of vitamin A of 2 microns or less in diameter dispersed in gelatin beadlets brought about 69% greater liver storage than was obtained with an oil solution. With 5-micron particle size the superiority was 24~o, and with 20-micron particle size liver storage was approximately the same as with an oil solution. The present investigation compares effectiveness for beef cattle of vitamin A in oil solution, in aqueous emulsion and dispersed in gelatin beadlets.