Pancreatic development in newborn guinea pigs fed breast milk versus intact or low-hydrolyzed protein formulas

Aim: To evaluate pancreatic development in newborn guinea pigs fed since birth intact or low-hydrolyzed protein formulas compared with breast milk. Methods: Forty-five newborn guinea pigs were allocated to three feeding regimens: breast milk (n = 15) and two isocaloric isonitrogen milk formulas containing intact (n = 15) or low-hydrolyzed proteins (n = 15). Body weight and food consumption were recorded every day. After 8 days, one third of pups from each group was killed, and the remaining animals were weaned. Another third was killed on day 14, and the remainders were killed on day 20. Zymogen storage was evaluated on pancreatic sections, whereas DNA and RNA concentrations were measured by a fluorometric method. Results: Compared with breast fed pups, both groups of artificially fed animals showed lower weight gain during the first 2 weeks of life but not after weaning. Both formulas fed groups had significantly lower amount of zymogen granules in pancreatic acinar cells at 8 and 14 days of life. This reduction was still present at day 20 in intact protein formula but not in low-hydrolyzed protein formula fed animals in which higher RNA/DNA ratio was also observed compared with breast fed pups. Conclusion: In newborn guinea pigs, artificial feeding is associated with reduced zymogen storage at days 8 and 14 of life. After weaning, cellular content of zymogen granules is comparable with breast fed pups only in low-hydrolyzed protein formula fed animals, even in the presence of some evidence of pancreatic hypoplasia.