Proteic-anabolic capacity in rats--influence of the quality and quantity of dietary protein.
The effect of quality (casein + 5% DL-methionine, normal or heated at 180 degrees C for 20 min) and quantity (4%, 6%, 10%, 15% and 20%) of dietary protein on food intake, weight increase and nitrogen retention, has been studied in both sexes weaning Nestle rats. Our results show that food intake, when expressed as g dry matter/100 g body weight and day, is not dependent on the quality and quantity of dietary protein. Weight increase goes up at a 10% dietary protein level. At higher protein levels (15% and 20%) values are only maintained. Protein quality do not cause any difference. Nitrogen retention goes up on increasing dietary protein level, with a maximum at 10% casein-methionine and 15% heated protein, being retention heated casein-methionine significantly lower. At a higher protein level, the maximal anabolic capacity for protein is maintained. Maximum Protein Productive Value (PPV) is obtained from diets containing 10% protein level (normal or heated). There is a significant decrease at higher protein levels (15% and 20%). The PPV of heated casein-methionine is lower than PPV of normal one at 6%, 10%, 15% and 20% protein levels. The results state that in our assays, in spite of the good quality of heated casein-methionine, its metabolic efficiency is below non heated protein values even when protein contribution is increased. We can assume that protein quantity is not a balancing factor for protein quality.
D000818:Animals; D002364:Caseins / Q000008:administration & dosage; D004032:Diet; D004044:Dietary Proteins / Q000008:administration & dosage* / Q000378:metabolism / Q000592:standards; D004305:Dose-Response Relationship, Drug; D005260:Female; D006128:Growth / Q000187:drug effects; D006358:Hot Temperature; D008297:Male; D008715:Methionine / Q000008:administration & dosage; D009584:Nitrogen / Q000378:metabolism*; D009753:Nutritive Value; D051381:Rats
D002364:Caseins; D004044:Dietary Proteins; D008715:Methionine; D009584:Nitrogen