PROTEIN-V ENZYMATIC PROTEIN HYDROLYSATES - NITROGEN-UTILIZATION IN STARVED RATS

The present study was carried out to compare the effects of four isoen ergetic and isonitrogenous diets on the N utilization, total serum pro tein concentration and serum amino acid profile in starved rats at wea ning. These diets differed only in the molecular form of two milk prot eins (whey protein and casein), which were either native or partly hyd rolysed. Male Wistar rats at weaning were fasted for 3 d and then refe d with one of the four diets for 48 h. No differences were observed in the body weight gain, protein digestibility and total serum protein c oncentration between groups after the refeeding period and all the N b alances were positive. N retention was higher in the two groups of rat s given the protein-hydrolysate-based diets compared with those given the intact-protein-based diets. This was associated with a lower urina ry N excretion in rats, given the whey-protein-hydrolysate and the cas ein-hydrolysate diets. Despite this fact, the serum amino acid pattern of rats given the hydrolysed protein diet was very similar to that of those given the corresponding native protein diet. In conclusion, we have proved that enzymic hydrolysates from milk proteins have equivale nt effects to native proteins in recovery after starvation in rats at weaning, on N absorption, total serum protein concentration and serum amino acid profile, and even give a higher N retention, We did not obs erve any harmful effect in using protein hydrolysates instead of nativ e proteins.