The effect of vitamin C supplementation on plasma concentration and urinary excretion of vitamin C in cattle.
We investigated the plasma concentration and urinary excretion of vitamin C in cows supplemented with vitamin C. Five cows (mean BW = 597 kg) were allocated to a 5 x 5 Latin square design and supplemented with a vitamin C preparation coated with hydrogenated soybean oil at 0, 10, 20, 40, or 60 mg of vitamin C per kg of BW per day for 9 d. Plasma and urine samples were collected for measuring vitamin C concentration. Urinary excretion of vitamin C was expressed as the ratio of vitamin C to creatinine. Plasma vitamin C concentration and urinary vitamin C excretion increased quadratically as dietary vitamin C increased (P < 0.001); that is, the lowest dose affected neither plasma vitamin C concentration nor urinary vitamin C excretion but the plasma vitamin C concentration and urinary vitamin C excretion increased (P < 0.05) with increasing supplementation of vitamin C at greater doses. This suggests that plasma vitamin C concentration affects urinary excretion of vitamin C in cattle and that plasma vitamin C concentration exceeded the renal threshold for vitamin C in the cows receiving vitamin C at 20 mg/kg of BW per day. Furthermore, increased urinary excretion of vitamin C appears to limit plasma vitamin C concentration in response to vitamin C intake. The daily excretion of vitamin C was estimated by the reported value of daily creatinine excretion, indicating that the daily amount of vitamin C excreted into urine was more than half of supplied vitamin C. Therefore, a large part of supplied vitamin C probably escapes ruminal degradation and is absorbed but excreted into urine.
Padilla
L
L
Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan.
Matsui
T
T
Ikeda
S
S
Kitagawa
M
M
Yano
H
H
D000818:Animals; D001205:Ascorbic Acid / Q000097:blood* / Q000494:pharmacology* / Q000652:urine*; D002417:Cattle / Q000097:blood / Q000378:metabolism* / Q000652:urine; D003404:Creatinine / Q000652:urine; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005260:Female; D007408:Intestinal Absorption; D011897:Random Allocation; D012417:Rumen / Q000378:metabolism; D014815:Vitamins / Q000097:blood / Q000494:pharmacology / Q000652:urine