Uncovering the physiological impacts of soybean meal replacement by Narbonne vetch (Vicia narbonensis) meal in rainbow trout (Oncorhynchus mykiss) diets: Towards the future and sustainable European aquaculture.

Red Vetchling (Lathyrus cicera L.), a Promising Crop for the Sustainable Replacement of Soybean Meal and Reducing the Carbon Footprint of European Aquafeeds

“…The profile of NSPs in red vetchling was similar to that of Narbonne vetch, another promising legume seed locally produced in Europe, with arabinose and glucose being the most abundant, and rhamnose and fucose not being detected [39]. Several reports evidenced how, as a consequence of NSP availability in legume seeds, substrates' accessibility to enzymes (and activity) and carbohydrates absorption were reduced, particularly glucose and plasma glucose levels (reviewed in [14]).…”

“…Lower glucose assimilation in the intestine would induce lower plasma glucose levels and, therefore, lower accumulation of carbohydrates in liver, reflected by lower HSI and reduced hepatocyte surface coverage (less hepatocyte vacuolization). Although in Toledo-Solís et al [39], lower amylase activity and gene expression, as well as altered carbohydrates metabolism, were correlated with lower hepatocyte surface coverage, no differences in plasma glucose 24 h post-feeding were observed when rainbow trout were fed a diet in which 66% SBM was replaced with Narbonne vetch. In the present study, a reduced glucose plasma level was clearly observed at 3 and 6 h post-feeding and remained even at 24 h postfeeding in fish fed T66 and T100 diets (66 and 100% of SBM replacement by red vetchling).…”

“…The inclusion of different types and levels of polysaccharides have shown different effects on diet digestibility parameters, with some classes of polysaccharide having greater effects than others [37]. Legume seeds contain a wide range of oligosaccharides that are not hydrolyzed by the endogenous enzymes from monogastrics, altering nutrient digestion [5] and, in particular, are known to contain specific NSPs decreasing intestinal transit, gastric emptying, and/or glucose absorption [12,13,38,39]. Reduced growth performance and the activity of some digestive enzymes (e.g., trypsin) have been reported in rainbow trout fed diets containing specific NSPs and/or plant protein sources containing high levels of different NSPs [39][40][41][42].…”

“…Legume seeds contain a wide range of oligosaccharides that are not hydrolyzed by the endogenous enzymes from monogastrics, altering nutrient digestion [5] and, in particular, are known to contain specific NSPs decreasing intestinal transit, gastric emptying, and/or glucose absorption [12,13,38,39]. Reduced growth performance and the activity of some digestive enzymes (e.g., trypsin) have been reported in rainbow trout fed diets containing specific NSPs and/or plant protein sources containing high levels of different NSPs [39][40][41][42]. Therefore, the presence of some particular NSPs in red vetchling might also be responsible for the lower protein apparent digestibility of the T100 diet.…”

“…contain amylase inhibitors [43]. Furthermore, the reduced enzyme activity of amylase and its gene expression, as well as the altered metabolism of carbohydrates at a transcriptional level reported in rainbow trout fed diets containing similar levels of Narbonne vetch [39], might also occur when they are fed diets containing red vetchling as they contain a similar profile of NSPs. In fact, this reported effect of NSPs on digestive enzymes is consistent with lower HSI, lower hepatocyte surface coverage, and decreased post-prandial plasma glucose and triglyceride levels in fish fed diets containing increasing levels of red vetchling.…”