Dietary lyophilized colostrum alters distribution of goblet cells and the intestinal epithelium of Piaractus mesopotamicus

Abstract

The intestinal epithelium is responsible for the first line of defense, directly influenced by bioactive, dietary molecules. The lyophilized bovine colostrum (LBC) is a nutraceutical and a surrogate protein source for farmed fish. This study aimed at evaluating distribution of goblet cells and morphometric changes in the intestinal epithelium of juvenile, neotropic Characin pacu Piaractus mesopotamicus fed diets containing 0%, 10% or 20% LBC for either 30 or 60days. Muscle layer thickness (MLT); partial volume of the absorptive mucosa (Vv); number of goblet cells containing acidic and neutral mucins and the acidic subtypes – sialomucin and sulphomucin, were studied in three intestinal segments (S1, S2, S3 and rectum). Fish fed 20% dietary LBC had enlarged MLT at 60days in S2 segment, and increased number of goblet cells containing neutral and acidic sulphomucin in S1, as well as number of goblet cells containing sulphomucin and sialomucin and total number of goblet cells in S2 at 60days. Juveniles fed 10% LBC diets had reduced number of goblet cells containing neutral mucin, acidic mucin and total number of goblet cells at 60days. The number of goblet cells containing sialomucin was higher in juveniles fed 20% LBC diets than those fed 0% and 10% LBC diets at 60days. Dietary LBC influenced the development of intestinal muscle layer and the volume of absorptive mucosa of juvenile pacu, improving capacity of nutrient and macromolecules absorption in S2 segment. The presence of unidentified substances from the bovine colostrum determined a reaction in intestinal epithelium with subsequent increased production of mucin. Statement of RelevanceAlternatives for fish nutrition are placed annually in the world market with the expectation of getting a quick performance at minimum cost. As an alternative animal food, lyophilized bovine colostrum may be innovative when added as a source of protein and bioactive peptides in fish food, such as neotropical fish species. The lyophilization process preserves the quality and unique features of colostrum, like antioxidant, immunological and antimicrobial proprieties. Additionally, the present work contributes to a better understanding of basic histology of neotropical fish species, that still demands for basic studies about enteric physiology. The presence and distribution of sialomucins, sulphomucins and neutral mucins in the intestinal epithelium of an omnivorous fish may contribute to the evaluation of nutritional alternatives that enable greater production efficiency at the national level. In this context, the present manuscript is complementary to others already published papers, which includes the study of the feasibility of using bovine colostrum as an alternative protein source for fish, as well as the consequences of the presence of biological active molecules, such as IGF-1, on the enteric histology and morphology.