For sixteen years, the American Institute of Nutrition Rodent Diets, AIN-76 and AIN-76A, have been used extensively around the world. Because of numerous nutritional and technical problems encountered with the diet during this period, it was revised. Two new formulations were derived: AIN-93G for growth, pregnancy and lactation, and AIN-93M for adult maintenance. Some major differences in the new formulation of AIN-93G compared with AIN-76A are as follows: 7 g soybean oil/100 g diet was substituted for 5 g corn oil/100 g diet to increase the amount of linolenic acid; cornstarch was substituted for sucrose; the amount of phosphorus was reduced to help eliminate the problem of kidney calcification in female rats; L-cystine was substituted for DL-methionine as the amino acid supplement for casein, known to be deficient in the sulfur amino acids; manganese concentration was lowered to one-fifth the amount in the old diet; the amounts of vitamin E, vitamin K and vitamin B-12 were increased; and molybdenum, silicon, fluoride, nickel, boron, lithium and vanadium were added to the mineral mix. For the AIN-93M maintenance diet, the amount of fat was lowered to 40 g/kg diet from 70 g/kg diet, and the amount of casein to 140 g/kg from 200 g/kg in the AIN-93G diet. Because of a better balance of essential nutrients, the AIN-93 diets may prove to be a better choice than AIN-76A for long-term as well as short-term studies with laboratory rodents.

The AIN-93 rodent diets were formulated to substitute for the previous version (AIN-76A) and to improve the performance of animals that consume them. They are called AIN-93G, formulated for growth, and AIN-93M, for maintenance. Major changes included substituting cornstarch for sucrose and soybean oil for corn oil and increasing the amount in order to supply both essential fatty acids (linoleic and linolenic). L-Cystine was substituted for DL-methionine to supplement the casein component. The mineral mix was reformulated to lower the amounts of phosphorus, manganese and chromium, to increase the amount of selenium, and to add molybdenum, silicon, fluoride, nickel, boron, lithium and vanadium. The amounts of vitamins E, K-1 and B-12 were increased over those in the AIN-76A vitamin mix. The AIN-93G diet contains 200 g of casein and 70 g of soybean oil/kg diet. The maintenance diet (AIN-93M) contains 140 g of casein and 40 g of soybean oil/kg diet. The 1993 diets have a better balance of essential nutrients than the 1976 diet and are better choices for studies with laboratory rodents.