Diet modifies elastase I and II activities and mRNA levels during postnatal development and weaning in piglets

Little information is available on the expression of pancreatic elastase I and II, despite their role in protein milk digestion. We studied the developmental changes and the effects of diet composition on both elastase I and II expression in suckled and weaned piglets. We measured their activities and levels of their corresponding mRNA. Forty-two piglets were assigned to seven groups according to age and diet. Piglets were slaughtered at birth (Group 1), or suckled up to 13 d (Group 2) or 21 d (Group 3), fed a milk substitute from 14 to 21 d (Group 4) or to 56 d (Group 7), suckled up to 21 d and then fed a dry starter up to 56 d (Group 5), or fed a milk substitute from 14 to 21 d and then a dry starter up to 56 d (Group 6). At 21 d pancreatic function was not modified by the source and the form of milk consumed. The specific activity of elastase II was maximum at birth and declined sharply thereafter, whereas that of elastase I markedly increased after weaning. The presence of milk protein in the diet did not prevent the sharp decrease in elastase II activity observed with age. During the 13 d period of suckling sow's milk, the mRNA patterns indicated that the regulation was at the mRNA and post-transcriptional levels, whereas after weaning and depending on the source of dietary protein, it was essentially translational and/or post-translational. Taken together, our results provide evidence of the early expression of elastase I and II genes that could enhance protein digestion. It seems that elastase II might be a predominant pancreatic protease during the milk-feeding period, whereas elastase I might be related to weaning.