EFFECTS OF 2 PROTEIN HYDROLYSATES ON GROWTH, NITROGEN-BALANCE AND SMALL-INTESTINE ADAPTATION IN GROWING RATS

The effects of feeding 2 protein hydrolysates, one prepared by control led pepsin and pancreatic protease (including elastase II) hydrolysis of milk proteins (PPPH) and the other a di- and tripeptide bacterial p rotease hydrolysate of bovine albumin (DTPH), on the growth, nitrogen balance and small intestine adaptation of growing rats were analyzed. Two groups of 3-week-old rats (8 rats/group) were fed the liquid diets ad libitum for 2 weeks. The diets had the same caloric, nitrogen, car bohydrate and lipid contents. The amino acid compositions fulfilled th e needs of growing rats. The diets differed in the original proteins, the hydrolysis technique used and the molecular weights of the peptide s. Nitrogen intakes were similar. Although there was no difference in weight gain, nitrogen balance was significantly higher in the rats fed the PPPH diet (day 4-day 6: PPPH, 60 +/- 4%, DTPH, 25 +/- 5%; day 12- day 15: PPPH, 58 +/- 3%; DTPH, 30 +/- 5%). The stool nitrogens were id entical, suggesting improved nitrogen storage in the rats fed the PPPH diet. Small intestine adaptation showed that the rats on the PPPH die t had significantly more protein (mg) and DNA (mu g) per 10 cm of the jejunum (PPPH, 25.6 +/- 2, 393 +/- 20; DTPH: 15.7 +/- 2, 258 +/- 23) a nd sucrase-specific activity and per mu g of DNA (PPPH, 133 +/- 5.7, 9 .7 +/- 0.5; DTPH, 113 v 5, 7 +/- 1). The N-aminopeptidase-specific act ivity was the same in both groups. These data show that PPPH leads to better nitrogen retention and small intestine adaptation in growing ra ts than does DTPH.