Dimethylbenzanthracene mammary tumorigenesis in sprague-dawley rats fed diets differing in content of beef tallow or rapeseed oil

Abstract

Female Sprague-Dawley rats fed purified diets containing 5% or 20% fat as beef tallow or rapeseed oil plus corn oil were given 2.5 mg 7,12-dimethylbenz(a)anthracene intragastrically at age 55 days. Mammary tumorigenesis was not significantly increased in rats fed diets high in beef tallow or rapeseed oil compared to rats fed 5% fat. In earlier studies in rats fed similar diets containing corn oil or lard, mammary tumorigenesis was enhanced by the high fat diets. These results indicate that dietary fats vary in their ability to increase mammary tumorigenesis in rats. In addition, body weight, feed efficiency ratios, sexual maturation, and estrous cycles were examined. High erucic acid rapeseed oil did not support growth as well as beef tallow, and feed efficiency ratios were decreased in animals fed the higher amount of the oil. There was no significant dietary fat effect on age at vaginal opening or regularity or duration of estrous cycles.