Body Composition,and Utilization of Protein and Energy in Growing Rats at Different Dietary Protein to Energy Ratios by Use of Purified Whole Egg Protein

A study has been made on growing rats to investigate the effect of variation in percentage of dietary protein calories from 0 to 50% by the use of purified whole egg protein on the growth, food efficiency, protein efficiency ratio (PER), body composition, and efficiencies of protein and energy utilization.

Body weight gain and PER attained a maximum, and food efficiency reached a plateau at 10 PC% (protein calories percent) in the diet, having a constant metabolizable energy content (410 kcal). Body and liver compositions changed in systematic patterns, where liver lipid content showed a specific increase at 5 PC%.

Body protein retention reached a plateau at 15 PC% but with little difference from the value at 10 PC%, while body lipid retention give a maximum at 10 PC% showing a gradual decrease thereafter.

Throughout the given dietary protein to energy ratios, energy utilization was constant when expressed as the increment of body energy retention divided by the increment of metabolizable energy intake. At and above 12 or 13 PC%, the efficiency of net body protein energy retention against metabolizable energy intake was constant at about 12.5% on the average.