A significant impairment in growth rate, food efficiency and weight of the gastrocnemius muscle was observed in rats fed a raw legume as the source of protein compared to casein-fed animals. No appreciable differences in chemical composition of the carcass were found. The source of dietary protein did not influence the ratio protein/DNA, DNA concentration or protein-synthesizing capacity (RNA/protein). The slower weight gain of animals fed the legume diet was attributed to a lower muscle protein synthesis, mediated by a depression of muscle RNA activity (grams protein synthesized/gram RNA) rather than changes in myofibrillar protein breakdown. In contrast liver protein synthesis appeared to be slightly increased in the legume-fed animals.

Total liver cathepsin A and D and gastrocnemius acid proteolytic activities have been evaluated in male growing rats fed ad libitum over periods of 15 and 30 days on 20%-protein diets containing either casein or raw field bean {Viciafaba L.) as protein sources. It has been found that, compared to the control casein-fed rats, those fed the legume diet exhibited a marked reduction (p < 0.05) in the rate of growth and protein efficiency rate; liver proteolytic activity increased with ageing in the two dietary treatments and was found to be significantly higher (p < 0.05) in the legume-fed rats. However, muscle proteolytic activity decreased with ageing and proved significantly increased (p < 0.05) in the legume-fed rats.