Effects of egg yolk proteins on the longitudinal bone growth of adolescent male rats.

Hen egg is a nutritional store for a new life. We examined the effect of egg yolk proteins on longitudinal bone growth in the rat. Protein fractions from egg yolk were tested. Milk protein, casein, was used as a control. The bone growth rate was significantly increased by yolk water-soluble protein (YSP, 100 mg/kg) administration for 5 d. The bone morphogenetic protein-2 immunostaining of growth plate was also increased. Considering the results, YSP can be used as a growth-promoting factor.