Diet for Fischer-344 rats in long-term studies.

The NIH-07 open-formula nonpurified diet (1) has been the selected diet for National Toxicology Program (NTP) studies since 1980. This diet was formulated about 20 years ago for reproduction, lactation, and growth of rodents in production colonies. This diet, which contains approximately 24% protein, 5% fat, and 3.5% fiber (2), may not be an optimal diet for rats in long-term studies, and some components such as protein may be increasing the severity of chronic diseases. A workshop on diet was held at NIEHS in Research Triangle Park, North Carolina-, on 23 June 1993 in conduction with the NTP Board of Scientific Counselors Technical Report Review Subcommittee meeting. Approximately 40 people from NIEHS, EPA, the Food and Drug Administration, pharmaceutical and chemical industries, and feed manufacturers attended the workshop. The purpose of the workshop was 1) to review the effects of changes in protein, fat, and fiber concentrations of diet on chronic disease (e.g., nephropathy), tumor incidences (e.g., leukemia, mammary and pituitary tumors), and survival of rats, especially Fischer-344 rats, in various 2-year studies conducted by NTP/NIEHS and 2) to discuss modification of diet composition and ingredients. The format of the workshop was 1) presentation of results of NTP/ NIEHS studies, related literature information, and proposed concentration of protein, fat, and fiber in the new diet followed by 2) discussion of each diet component by the consultants, members of the NTP Board of Scientific Counselors Subcommittee and other participants.