Muscle protein turnover in rats fed on diets containing different levels of Vicia faba L. and casein as source of protein

The effects of intake of Vicia faba L. and casein as the sources of protein on protein synthesis and breakdown were investigated. The results showed that the protein deposition as a percentage of body weight as well as the muscle and myofibrillar nitrogen content are not altered by the experimental diets. The values of myofibrillar gain (mg N2/day) were higher in the animals fed on casein diets than those fed on legume protein at both levels (12 and 18%) while no differences were found in the myofibrillar protein breakdown assessed by the urinary excretion of 3-methylhistidine. Therefore, it is suggested that the stunting of growth is not due to an increased protein degradation, but an impaired protein synthesis.