Oil in a commercial standard diet needs its product specifications.

As our survey found that some commercial standard diets for laboratory animals contained oil with chemical properties of highly deteriorated oil, their influence should be checked on animals especially of very young age. Three-week old weanling Wistar rats were fed a commercial standard diet (commercial standard diet group) or AIN93G (AIN93G group), defined diet, for 7 weeks. Then both groups were fed AIN93G for 12 weeks. As a result, all the rats grew normally without diarrhea, seborrhea, dermatitis, or excessive hair loss through the feeding period and there was no significant difference in body weight increase, feed ingestion amounts and organ weights. But fecal excretion was high at 10 weeks of age when the diet was switched from the commercial standard diet to AIN93G. Although serum aspartate aminotransferase (AST) and alanin aminotransferase (ALT) of the commercial standard diet group were not statistically higher than those of the AIN93G group, two rats out of 8 in the former group showed dark-red patches on the liver surface, and necrosis in histological analysis. In addition, slight fatty degeneration of all the liver, and swelling tubuler epithelium of kidneys were also found in the group. Serum levels of triacylglycerol (TG), glucose (GLC) and total cholesterol (T-CHO) were high, and free fatty acids (NEFA), low in the commercial standard diet group in good accordance with our previous result from the study on ingestion of deteriorated oil. In conclusion, product specifications of oil in commercial standard diets should be laid down to pursue a reliable animal experimentation.