Estimation of the dietary iron requirement for the weanling puppy and kitten

An estimate of the dietary requirement for iron (Fe) has never been made for the growing canine or feline. Therefore, two assays were conducted in which weanling puppies or kittens were fed a casein-based, fiber-free diet containing 5, 30, 55, 80, 105, or 130 mg/kg Fe (supplied as FeSO4 X 7H2O) for 30 d. Blood samples were obtained and body weight measured at 10-d intervals. Hemoglobin concentration and hematocrit were determined and a one-slope broken-line model analysis of these two parameters was used to estimate the dietary Fe requirement for each species. For the puppy, 84 +/- 6.1 mg dietary Fe/kg was necessary to maximize hemoglobin concentration, whereas 81 +/- 5.0 mg dietary Fe/kg was the requirement estimate using hematocrit as the response criterion. For the kitten, requirement estimates were 77 +/- 8.1 and 80 +/- 7.2 mg dietary Fe/kg for maximizing hemoglobin concentration and hematocrit, respectively. We conclude that at least 80 mg dietary Fe/kg is required by growing dogs and cats fed a purified casein-dextrose diet.