The effect of vitamin C supplementation on plasma concentration and urinary excretion of vitamin C in cattle

¹ Division of Applied Biosciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
² Livestock Farm, Graduate School of Agriculture, Kyoto University, 144 Tomitakomono, Kyotanba-cho, 622-0203, Japan

^* To whom correspondence should be addressed. E-mail: matsui{at}kais.kyoto-u.ac.jp.

	Abstract

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, and 60 mg vitamin C · kg BW^-1 · d^-1 for 9 d. Plasma and urine samples were collected for measuring vitamin C concentration. The urinary excretion of vitamin C was expressed as the ratio of vitamin C to creatinine. The plasma vitamin C concentration and urinary vitamin C excretion increased quadratically as dietary vitamin C increased (P < 0.001), i.e., 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 BW^-1 · d^-1. Further, 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 excreted vitamin C 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 is excreted into urine.

Key Words: Cattle, Plasma, Urine, Vitamin C