Effect of Dietary Protein and Energy on the Nitrogen and Energy Utilization in Growing Rats

단백질과 에너지 수준이 흰쥐의 질소와 에너지 이용에 미치는 영향

  • Chang, Yu Kyung (Dept. of Food and Nutrition, College of Home Economics, Hanyang University) ;
  • Kwon, Soon Hyung (Dept. of Home Economics, SangJu Agriculture Junior College) ;
  • Han, In Kyu (Dept. of Animal Science, College of Agriculture, Seoul National University)
  • 장유경 (한양대학교 가정대학 식품영양학과) ;
  • 권순형 (상주농업전문대학 가정과) ;
  • 한인규 (서울대학교 농과대학 축산학과)
  • Received : 1983.07.28
  • Published : 1983.09.30


In order to investigate the effect of dietary protein and energy on growing female and male rats, Sprague-Dawley 90 female rats and 54 male rats of 3 weeks old weighing approximately 70-80g and 54-75g, respectively, were subjected feeding trials for 8 weeks and then subsequently to metabolic trials for 2 weeks. Three dietary energy levels(3,200, 3,600, 4,000 kcal/kg) were employed and each energy level contained three protein levels (15, 25, 35% of 3600 kcal ME/kg) and three rat levels (10, 20, 40% of 3,600 kcal ME/kg) by addition of an appropriate amount of carbohydrate and the following result were obtained. As the protein level was increasing, digestibilities of dry matter and carbohydrate tended to decrease whereas that of protein was slightly increasing. On the other hand, digestibility of fat was always very high regardless of the level of protein but that tended to be slightly improved as the level of energy or rat increased. The digestibilities of female and male rats tended to be same. The digestibilities of dry matter, crude protein, crude fat and carbohydrate were 83%, 90%, 96% and 93%, respectively, and they were neither affected by protein and energy levels nor observed differently depending upon the sex. Nitrogen retention of female and male rats were best for LPHE ration. In other words, both nitrogen retention was improved as the level of energy increased and the level of protein decreased. The gross energy intake was high at low protein level in female rats and at medium protein level in male rats. That tended to decrease as the level of energy increased in female rats whereas that was not affected by the level of energy in male rats. The metabolic energy efficiency was highest for LPHE ration in female rats and for LPME ration in male rats.