title: Effects of gamma irradiation and pasteurization on the nutritive composition of commercially available animal diets.
abstract: Gamma radiation is used to sterilize diets for specific pathogen-free (SPF) animals. Because a gamma-irradiated diet was linked to leukoencephalomyelopathy in SPF cats, we investigated the effects of 'typical' (28.9-34.3 kGy) and 'high-end' (38.4-48.7 kGy) doses of gamma irradiation and of pasteurization (at 107 degrees C for 15 min) on the amounts of fat; protein; carbohydrate (and taurine in cat diet); vitamins A, E, B1, B2, B6, and B12; and peroxide in commercially available dry cat, dog, and rodent diets. The only treatment-related changes occurred with vitamin A and peroxide. The typical and high-end doses of gamma irradiation reduced the vitamin A level of the cat diet to 42% and 30% of the untreated value, respectively-levels below recommended allowances for growth and reproduction. Only the higher irradiation dose reduced vitamin A in the rodent diet, and neither dose altered the canine diet. Pasteurization reduced the vitamin A content of the cat diet to 50% of its original level, which was within the recommended level for this species. Irradiation increased the peroxide content of all 3 animal diets: by approximately 11-fold with the typical dose and by 14- to 25-fold with the high-end dose. Therefore gamma irradiation can have profound, selective effects on the vitamin A and peroxide contents of dry diets, and caution is advised when feeding such diets long-term and exclusively to SPF animals, particularly cats. Furthermore, pasteurization (with its fewer deleterious effects) may represent an alternative method of decontaminating diets for rodents, dogs, and cats.
authors.affiliation: Department of Pharmacology and Therapeutics, National University of Ireland, Galway, Ireland.
authors.forename: Catherine D
authors.initials: CD
authors.lastname: Caulfield
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Cassidy
authors.forename: John P
authors.initials: JP
authors.lastname: Kelly
mesh_terms: D000818:Animals; D000830:Animals, Laboratory; D002415:Cats; D004032:Diet / Q000662:veterinary*; D004040:Dietary Carbohydrates / Q000032:analysis; D004041:Dietary Fats / Q000032:analysis; D004044:Dietary Proteins / Q000032:analysis; D004285:Dogs; D005514:Food Irradiation / Q000009:adverse effects*; D005519:Food Preservation / Q000379:methods*; D005720:Gamma Rays; D006358:Hot Temperature / Q000009:adverse effects*; D010545:Peroxides / Q000032:analysis; D012377:Rodentia; D013047:Specific Pathogen-Free Organisms; D013242:Sterilization; D014815:Vitamins / Q000032:analysis
chemical_list: D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D010545:Peroxides; D014815:Vitamins