Effect of Autoclaving and Lysine Supplementation of Skim-Milk-Powder Diets on Growth and Caries in Rats

¹ Department of Physiology and Nutrition, University of Texas Dental Branch, Houston, Texas

The results of this study showed that the relationship of lysine to growth and dental caries in animals fed milk-powder diets was different in males and females. When the milk-powder portion of the diet was autoclaved, growth in male rats was depressed during the period of rapid growth between the fifth and ninth weeks. Growth was restored by supplementation with L-lysine hydrochloride. Neither autoclaving the milk powder nor lysine supplementation altered the growth response of females. It appeared that these diets were nutritionally adequate for the females but were marginally deficient for the males.

All the skim-milk-powder diets produced smooth-surface caries in both sexes, but the incidence was higher in the females. Lysine supplementation did not reduce caries in the males; however, in the females, lysine was anticariogenic in both autoclaved and unautoclaved skim-milk-powder diets. This anticariogenic effect of lysine in the females was found in the absence of any effect on growth attributable to a lysine deficiency. Autoclaving the milk powder did not increase the cariogenicity of the diet in either sex. These studies indicated that the females were sensitive to the anticariogenicity of lysine and that this was not related to the growth-promoting quality of the skim-milk-powder diets.

The data obtained in the study of femurs, livers, and other organs revealed no effects that could be correlated directly with the growth and caries found in this experiment.