The Vitamin A and E Forms Influence Differently the Plasma Vitamin Concentrations in Newly Received Calves

Ten Holstein steer calves (105±3 kg) were used to evaluate bioavailability of two Vitamin A or E forms, “natural” (EA1) or “synthetic” (EA2), based on plasma vitamin concentrations during a 3-d period post injection(subcutaneous). Plasma retinyl palmitate and plasma Vitamin A concentration (retinol equivalent of all forms) was greater 24 and 48 h (P<0.01) post injection of retinyl palmitate vs retinyl propionate. Likewise, plasma retinol was greater (P = 0.04) 72 h post injection of retinyl palmitate. Plasma retinyl propionate was undetected for either treatment, indicative that it is not absorbed as a parent compound. Plasma retinyl palmitate, retinol and total Vitamin A concentrations peaked 24 h (P<0.01) post injection, decreasing toward baseline levels by 72 h post injection. Plasma tocopherol concentration was greater 24 h post injection (P<0.01) for calves injected with D-α-tocopherol vs DL-α-tocopherol. Levels were not different among treatments 48 h post injection (P>0.10). Plasma tocopherol concentrations were maximal (P<0.01) 24 h post injection of D-α-tocopherol, promptly decreasing by 72 h post injection (a level comparable to that observed with DL-α-tocopherol injection). We concluded that based on plasma concentrations, bioavailability of parenterally supplemented retinyl palmitate and D-α-tocopherol are greater than that of retinyl propionate and DL-α-tocopherol under acute Vitamin A or E supplementation.