|Morrill, S - KANSAS STATE UNIVERSITY|
|Velazco, J - SUPERIORES DE MONTERREY|
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 6, 1996
Publication Date: N/A
Interpretive Summary: Vitamin E is associated with increased immune functions in cattle. However, some milk replacers for calves contain high concentrations of vitamin A and minimal concentrations of vitamin E. Also, cattle are exposed to many stressors that decrease plasma vitamin E. Two experiments were conducted to examine availability of vitamin E fed to dairy calves. When vitamin A and E were fed together, plasma vitamin E concentrations were lower than when only vitamin E was fed. However, feeding vitamin A and E together did not change the calve's plasma vitamin A. The natural form of vitamin E increased blood plasma and kidney vitamin E concentrations but concentrations were similar for both forms in the red blood cell layer of the blood, and certain organs (spleen, liver, adipose tissue, muscle, and of the heart. These experiments showed two factors that can potentially increase vitamin E pools in cattle after short term delivery. The first experiment demonstrated that large vitamin A concentrations may inhibit the availability of some of the vitamin E which is in the same feeds of cattle. Secondly, the natural form increased vitamin E concentrations when fed only once, 24 hours before slaughter. Increasing concentrations of vitamin E at slaughter can be beneficial for the appearance and prolong the shelf-life of the finished product. These results are important to producers and ruminant nutritionists.
Technical Abstract: Two experiments were conducted to examine the effects of form of alpha-tocopherol or interactions with vitamin A on its bioavailability. In experiment 1, Holstein steers were fed a diet low in vitamins A and E for 1 mo., then blocked by BW (mean=97.5 kg) and assigned randomly to one of four oral treatments: 1) no added vitamins, 2) 442 mg of retinyl acetate, 3) 1342 mg of D-alpha-tocopherol, or 4) 442 mg of retinyl acetate and 1342 mg of D-alpha-tocopherol, each given as a pulse dose. Blood was sampled over a 36-h period. Concentrations of plasma retinyl palmitate peaked at 2 to 6 h post-supplementation for all calves and then peaked again at 22 to 28 h for calves receiving vitamin supplements. Concentrations of plasma alpha-tocopherol peaked earliest with D-alpha-tocopherol supplementation alone at 12 to 20 h after supplementation, but simultaneous supplementation with retinyl acetate resulted in lower plasma alpha-tocopherol concentrations. Plasma retinyl palmitate decreased during peak alpha-tocopherol concentrations. In Experiment 2, blood and tissue were analyzed after a one time gastric tube administration of a powder (DL-alpha-tocopheryl acetate) or a liquid (D-alpha-tocopherol) form of Vitamin E to Holstein calves. D-alpha-tocopherol increased plasma and kidney alpha-tocopherol concentrations compared with those of calves fed the DL-alpha-tocopherol acetate form. Concentrations in the liver, spleen, adipose tissue, heart, muscle, cellular blood fraction, and gut concentrations did not differ between the two forms.