VITAMIN-C SUPPLEMENTATION OF SLED DOGS AF FECTS RESPONSES TO RACING AND STRESS

The influence of dietary zinc and vitamin C on blood concentrations an d performance ratings was studied in 32 racing sled dogs of champion q uality. They were selected into blocks of four on the basis of sex, ag e and running ability. One from each group was assigned randomly to on e of four diets. The proportions of protein, fat, carbohydrate were ap proximately 30, 60, 10 on the basis of metabolizable energy in the bas al diet, which was fortified with vitamin and minerals to meet standar ds specified by the National research Council. The four diets were bas al, basal plus both supplements. Blood samples were taken in October, December, March and April. Microhematocrits were determined. Plasma wa s assayed for vitamins A, E, and C. Serum was assayed for zinc, copper and iron. The dogs were rated for performance and degree of stress af ter each run according to a standard set of physcial and behavioral si gns. All variables responded significantly to dietary supplementation. Serum ascorbate declined during the racing season, and this decline w as diminished by supplementation. Serum ascorbate also correlated sign ificantly with the performance ratings. The results indicate that supp lementary vitamin C may be beneficial in racing sled dogs.