The protein requirement of adult marmosets: nitrogen balances and net protein utilization of milk proteins, soy protein, and amino acid mixtures.

Nitrogen balance studies were conducted in adult male marmosets (Callithrix jacchus) using purified and semipurified diets with protein levels between 0% and 7%. Daily nitrogen loss in a state of prolonged protein free nutrition was 131 +/- 16 mg/kg body weight0.75. Zero nitrogen balance resulted from mean daily intake of 261 mg nitrogen/kg0.75 when high quality protein sources were used. Very low protein intake or the lack of arginine and histidine in an amino acid mixture induced coprophagy. It is concluded that the protein requirement of adult marmosets is very similar to the protein requirement of adult humans (based on metabolic body weight). About 6-7% high quality protein, based on dry matter, suffice to avoid a negative nitrogen balance in all individuals.