A NEW AUTOCLAVE SYSTEM FOR STERILIZING VITAMIN-FORTIFIED, COMMERCIAL RODENT DIETS WITH LOWER NUTRIENT LOSS

The study was designed to develop a method for sterilizing vitamin-fortified commercial diets for feeding germ-free and defined-flora rodents that would (a) require less time and (b) not destroy vitamins. Feed contaminated with Bacillus stearothermophilus and B. subtilis was sterilized in high-temperature, high-prevacuum autoclave and assayed for vitamin A, thiamine, and pantothenic acid. It was found that: (1) The use of high-temperature, high-prevacuum autoclaves makes possible a reduction in the time required to sterilize autoclavable, commercial diets. Previous methods have required temperatures ranging from 225 to 255F for 25 min to 1 hr to sterilize pelleted diets adequately. The procedure described in this report requires an autoclave cycle of only 12 min and a temperature of 275F. The sterilized feed can be removed from the autoclave 18 min after initiation of the cycle. (2) Sterilization by the method described reduces the loss of vitamin A, thiamine, and pantothenic acid. This study also showed that pelleted rodent diets in quantities of at least 50 lb can be sterilized in open bulk containers. (Author)