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Image 77 of Progress report (Kentucky Agricultural Experiment Station) n.176

Part of Kentucky Agricultural Experiment Station

..75. Procedure The common bile ducts of sheep were cannulated with 2 mm I. D. plastic tubing. Re-entry cannulae were placed in the small intestine near the juncture of the bile duct ` and small intestine. All sheep were injected intrajugularly with either 3Hvitamin A ~ acetate or 14Cbeta-carotene in an aqueous solution of 20% polyoxyethylene sorbitan monooleate (Tween 80). Total bile was collected at timed intervals with a fraction collector for 24 hours after injection. Results and Discussion ` In three trials, 35.5 uc of 3H-vitamin A acetate with a specific activity of 213 uc/mg were injected intravenously. An average of 21. 4% of the injected radioactivity appeared in the bile during the following 24-hr intervals. In duplicate trials, 4. 4 uc A of MC-betacarotene with a specific activity of 13. 2 uc/mg were injected intravenously. During the ensuing 24-hr interval, an average of 16. 4% of the injected radioactivity was secreted into the bile. In a third trial, 20. 0% of the injected radioactivity appeared ` in the bile during a 21. 5-hr collection period. These data suggest that secretion of vitamin A metabolites in the bile is of major importance in the vitamin A metabolism of ruminants. Further experiments have been initiated in an attempt to characterize the metabolites secreted, to study the re- absorption of the metabolites, and to determine their biological potency. LOSSES OF VITAMIN E FROM THE PREINTESTINAL DIGESTIVE TRACT OF STEERS . N. E. Alderson, G. E. Mitchell, Jr., C. O. Little, and R. L. Warner . Recent reports of increased gains with supplemented vitamin E in steers fed nohay finishing rations and the role of vitamin E in protecting milk from oxidized flavors have increased interest in vitamin E utilization by ruminants. Vitamin E is closely associated with vitamin A in its solubility in fat, its distribution in fatty tissues in the body, and its role in protecting vitamin A from oxidative destruction. Extensive " pre-intestinal disappearance of vitamin A has been demonstrated in both cattle and . sheep, and destructive activity in the rumen and abomasum is probably the major factor in this disappearance. If vitamin E is affected in a similar manner, pre-intestinal action on dietary vitamin E might exert a major influence on the vitamin E status of ' ruminants. The experiments reported here were designed to study possible pre- intestinal loss of vitamin E in steers fed different levels of concentrates. " Procedure Four mature steers fitted with permanent abomasal fistulas were each fed 5 kg per day of rations containing 20, 40, 60, and 80 percent corn in ascending then , descending order of corn content, with two observations per steer in each of eight 22-day treatment periods. After a 13-day preliminary period for each ration, each steer was treated on the 14th day and 21st day with 20, 000 I.U. alphatocopherol, 1, 000,000 I.U. vitamin A in 19 ml aqueous tween "80", 20 gm chromic oxide and 20 gm polyethylene glycol (M.W. 4000) in gelatin capsules. Abomasal collections, taken

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