A CONTRIBUTION TO THE BETA-CAROTENE AND V ITAMIN-A METABOLISM IN HORSES

16 horses ingested a daily ration, containing 60% hay and 40% concentr ates. For each 8 horses the mixed feed was supplemented with 2,3 mg be ta-carotene or 295 mu g vitamin A/kg bw/d. Carotene and retinol were d etermind in the plasma acid after euthanisation (adaptation for at lea st 4 weeks) in the liver (n=15), ovary (n=10) and in the fluid of vari ous follicles (n=37). beta-carotene supply resulted in an increase of plasma carotene to 250 mu g/l, while neither the beta-carotene nor the vitamin A supplementation influenced the retinol content in the plasm a (figure 1). The vitamin A content in the liver increased after vitam in A supply (800 mu g/g fresh matter, figure 2). The carotene content was not influenced by the treatments. Feeding beta-carotene resulted i n a significant increase of beta-carotene and retinol in the follicle fluid (table 2).