Effects and Safe Inclusion of Narbonne Vetch (Vicia narbonensis) in Rainbow Trout (Oncorhynchus mykiss) Diets: Towards a More Sustainable Aquaculture

Abstract

Aquaculture’s sustainability deeply relies on the identification and inclusion of alternative raw materials. Although meals from insects and/or byproducts from different industries are being recently tested, the meal from terrestrial vegetable species is still the main substitution candidate for fish meal. Here the effects of 0% (Control), 10% (A10) and 30% (A30) inclusion of Narbonne vetch (Vicia narbonensis; ZV-156 strain) meal in rainbow trout (Oncorhynchus mykiss) diets was assessed in a 63-day feeding trial by means of growth performance, histopathological, nutritional value of the fish fillet and blood biochemistry analyses. A dose-response trial was conducted in triplicate with 25 rainbow trout juveniles (20 g average body weight) per 500 L tank. Narbonne vetch meal decreased total intestine protease activity in vitro (from 26.81% to 48% inhibition), although high temperature partially inhibited the action of antinutritional factors (ANFs). No differences in fish growth performance and no severe histopathological alterations on the proximal intestine were observed between 10% Narbonne vetch inclusion and Control groups. In contrast, high inclusion (30%) of Narbonne vetch led to poor growth performance (30% reduction on final growth) and severe histopathological alterations (e.g., loss of brush border integrity, high number of villi fusion, reduced goblet cells density as well as reduced width of submucosa, muscular and serosa layers). Furthermore, while the A30 diet decreased docosahexaenoic fatty acid (FA) content in fish fillets, the A10 diet improved monounsaturated FA content when compared to that of the Control group. No altered levels of cholesterol, glucose or triglycerides in blood plasma and/or histopathological effects on the liver were observed among fish fed the different experimental diets. Although further research efforts (e.g., identifying potential enzymatic treatments to decrease the action of ANFs from Narbonne vetch meal) might be required, present results show that a low inclusion (10%) of Narbonne vetch in rainbow trout diets is possible. The inclusion of locally produced legumes such a Narbonne vetch might be an interesting approach to reduce carbon footprint in European aquaculture and the dependency on other alternative raw materials such as soybean (Glycine max) imported from third countries.

Dietary Curcumin Promotes Gilthead Seabream Larvae Digestive Capacity and Modulates Oxidative Status

“…Moreover, survival rate at the end of the experiment was 4-5-fold lower compared to previous experiments with gilthead seabream at mouth opening, reared at similar conditions [38,59]. The larvae survival when weaning is started at mouth opening is usually lower when compared to a late weaning in older larvae (16)(17)(18)(19)(20)(21)(22), that can vary between 11-56% [60][61][62]. However, it was similar among treatments, implying that curcumin supplementation had no effect on the observed survival rates.…”

“…All treatment showed a significant positive correlation between feeding incidence and larvae ag (CTRL-p = 0.002; LOW-p = 0.019; HIGH-p = 0.010, Figure 2). (5,6,8,12,16,20,23, and 28 days after hatching, DAH) fed experimental diets (CTRL, LOW, and HIGH). Values are expressed as mean ± SD.…”

“…The use of plant extracts as dietary supplements to promote health and growth performance in aquaculture production is gaining attention [20]. Curcumin, a pigment extract from the rhizome of turmeric (Curcuma longa), has been widely used for centuries in Southeast Asia in Ayurvedic medicine and consumed as a spice, flavoring agent, food preservative, and colorant [21].…”

Successful Inclusion of High Vegetable Protein Sources in Feed for Rainbow Trout without Decrement in Intestinal Health

“…Furthermore, in the present study a lower GC number was found in both PI and DI of fish fed FM0 diet. A reduction in GC might denote an immunosuppression in rainbow trout fed diets without FM, such has been shown in previous studies carried out on rainbow trout fed PP for 63 days [ 83 ]. Goblet cells maintain the epithelial homeostasis through the secretion of a mucosal barrier that acts as a lubricant, preserving the epithelium, although some studies support that GC can act as a major cellular component of the innate and adaptative defense system [ 84 ].…”

Effects of Randomly Fired Underwater Currents as an Occupational Enrichment Program in Rainbow Trout (Oncorhynchus mykiss)

“…Rainbow trout (Oncorhynchus mykiss) are native to tributaries of the Pacific Ocean in Asia and North America, and have been introduced worldwide for sport fishing and commercial aquaculture [1]. Currently, they are one of the most largely farmed fish species worldwide (>848,000 t y), the biggest in the European (185,316 t) region and the second most common species produced in Spain (18,955 t) [2]. Salmonids evolved in natural systems with considerable environmental complexity and, as such, can exhibit numerous behavioral options in response to environmental challenges [3].…”