Effect of hepatic folic acid status on formic acid metabolism in blue foxes (Alopex lagopus)

Fifty pairs (experiment 1) of 7-week-old blue fox (Alopex lagopus) cubs (live-weight 1.9 kg) were fed incremental level of folic acid (0, 5, 10, 20 and 40 mg kg −1 dry matter (DM)), for 4 weeks in order to investigate the effect of folate status on formate metabolism in blue foxes. Incremental folic acid feeding increased hepatic folate concentrations curvlinearly (351, 1024, 1161, 1280, and 1290 g 100 g −1 ). Seven males per feeding group were injected i.p. sodium formate once, 500 mg kg −1 live-weight, after which serum formate concentrations were determined from blood samples taken at 60, 90, 120 and 180 min post-injection. Incremental dietary folic acid decreased half-life of formate (173, 130, 126, 112, and 117 min, linear effect: P< 0.05, quadratic effect: P< 0.05) and increased formate disappearance rate (2.1, 2.7, 3.2, 3.2, and 3.4 mg l −1 min −1 , linear effect: P< 0.05). The effect of dietary formate intake on formic acid metabolism was studied with eight blue foxes (live-weight 8.45 kg) (experiment 2). Foxes were given formate either at a low (10.1 g kg −1 DM) or a high dietary concentration (19.7 g kg −1 DM). Foxes on high formate diets had higher mean serum formic acid concentration than foxes on low formate diets ( P< 0.01) (0.13 mg l −1 versus 0.05 mg l −1 ). The results of these experiments give new information in order to assess recommendations for the use of ensiled feedstuffs in blue fox diets. © 2002 Elsevier Science B.V. All rights reserved.