The riboflavin requirement of adult dogs at maintenance is greater than previous estimates.

A study was conducted to determine the riboflavin requirement of adult dogs at maintenance. Twenty adult mixed breed dogs were fed a semipurified meal with one of five riboflavin concentrations: Diet 1, 1.7 mg/kg; Diet 2, 2.7 mg/kg; Diet 3, 3.7 mg/kg; Diet 4, 4.7 mg/kg; and Diet 5, 5.7 mg/kg. The erythrocyte glutathione reductase activity coefficient (EGRAC) was used to determine biochemical riboflavin deficiency. Dogs fed Diet 1 had a greater (P < 0.05) EGRAC (1.24) on d 56 of the trial compared with that of dogs fed Diet 5 (1.11), indicating marginal riboflavin deficiency in dogs fed Diet 1. On d 84 the mean EGRAC for dogs fed Diet 1 (1.36) was different from EGRAC obtained for dogs fed the other diets (1.19, P < 0.05). The difference in mean EGRAC was still present of d 112 (1.59 vs. 1.27; P< 0.01). There was no difference in d 112 mean EGRAC for dogs fed Diets 2, 3, 4 and 5 (P < 0.05). The broken line requirement estimate for the adult dog at maintenance was determined to be 66.8 microgram riboflavin x kg body wt(-1) x d(-1) using the d 112 EGRAC as the basis for assessing biochemical riboflavin deficiency.