Dietary soya saponins increase gut permeability and play a key role in the onset of soyabean-induced enteritis in Atlantic salmon (Salmo salar L.)

Abstract

Saponins are naturally occurring amphiphilic molecules and have been associated with many biological activities. The aim of the present study was to investigate whether soya saponins trigger the onset of soyabean-induced enteritis in Atlantic salmon (Salmo salar L.), and to examine if dietary soya saponins increase the epithelial permeability of the distal intestine in Atlantic salmon. Seven experimental diets containing different levels of soya saponins were fed to seawater-adapted Atlantic salmon for 53 d. The diets included a fishmeal-based control diet, two fishmeal-based diets with different levels of added soya saponins, one diet containing 25 % lupin kernel meal, two diets based on 25 % lupin kernel meal with different levels of added soya saponins, and one diet containing 25 % defatted soyabean meal. The effect on intestinal morphology, intestinal epithelial permeability and faecal DM content was examined. Fish fed 25 % defatted soyabean meal displayed severe enteritis, whereas fish fed 25 % lupin kernel meal had normal intestinal morphology. The combination of soya saponins and fishmeal did not induce morphological changes but fish fed soya saponins in combination with lupin kernel meal displayed significant enteritis. Increased epithelial permeability was observed in fish fed 25 % defatted soyabean meal and in fish fed soya saponin concentrate independent of the protein source in the feed. The study demonstrates that soya saponins, in combination with one or several unidentified components present in legumes, induce an inflammatory reaction in the distal intestine of Atlantic salmon. Soya saponins increase the intestinal epithelial permeability but do not, per se, induce enteritis.

The Utilization of Soybean Meal in Formulated Diet for Marble Goby, Oxyeleotris marmoratus

“…However, other anti-nutritional factors such as saponins and antigenic compound could be existed (Yang et al, 2010). Saponins in soybean product was reported to affect the fish appetite (Bureau et al, 1998) and it was also reported by Knudsen et al (2007) that soya saponins, in combination with one or several unidentified components in soybean might induce inflammatory reaction in the distal intestine of Atlantic salmon. The presence of such anti-nutritional factors in the higher soybean meal level diets in this present study may lead to the poor appetite of the fish and the enteritis symptoms as observed in marble goby juvenile.…”

Criteria for Safe Use of Plant Ingredients in Diets for Aquacultured Fish

“…Alvarez and Torres-Pinedo (1982) suggested that soybean lectin bound to rabbit jejunal enterocyte apical membranes has a potentiating effect on saponin's detrimental influence on epithelial barrier function. Knudsen et al (2008) recently demonstrated that adding purified saponins from soybeans to a fishmealbased diet did not elicit an inflammatory response in the distal intestine or changes in faecal dry matter, and caused only minor changes in intestinal permeability compared to the same diet without saponins added. Nor did lupin kernel meal from sweet lupins (L. angustifolius) elicit inflammation.…”

Analysis of the Gut Microbiome of Nile Tilapia Oreochromis Niloticus L. Fed Diets Supplemented with Previda® and Saponin

“…Saponins are secondary plant compounds that have been tested in aquafeeds with different results. While some reports documented the toxic effect of saponin in fish and its negative effects to the gut epithelium (Knudsen et al, 2008), some studies concluded saponin promotes growth (Francis et al, 2005). Furthermore, saponin has been studied as a natural steroid to promote sex inversion to an all-male population, which could represent an alternative to the use of androgenic hormones in tilapia culture (Francis et al, 2002).…”