six groups of rats were fed , for 21 d , on six different diets based on combinations of two levels of dietary protein ( low protein , 75 g/kg ; high protein , 200 g/kg ) and three levels of zinc ( low zn , 0.9 microgram/kg ; moderate zn , 55 micrograms/kg ; high zn , 110 micrograms/kg ) .
C0012177
dietary protein
C0033684
protein