Carbohydrate utilisation by tilapia: a meta‐analytical approach

Abstract

Currently, studies reporting the digestibility of carbohydrates, starch and especially non‐starch polysaccharides (NSP) in fish are scarce. Carbohydrate digestibility in the diet is largely dependent upon carbohydrate composition (starch vs. NSP). NSP are often considered to be indigestible and thus of no nutritional value. The present study reviews carbohydrates in fish feed, distinguishing between total carbohydrate, starch and NSP. Besides a qualitative approach, a meta‐analysis was performed, compiling available data from digestibility studies on tilapia. Our meta‐analysis confirms the negative effect of NSP on performance (FCR) and nutrient digestibility (crude protein, fat and energy). However, an average NSP digestibility of 24.3% was calculated in 95 cases. Out of these 95 cases, 88% of them showed a positive NSP digestibility. NSP digestibility was shown to contribute to energy digestibility. The digestion of NSP in fish is associated with fermentation in the gut, producing beneficial volatile fatty acids that are rapidly absorbed by the colonic lumen. Therefore, in diet formulation, digestibility and thus energy originating from NSP should be taken into consideration because NSP contribute to the energy needs of fish, here tilapia. Besides being an energy source, specific types of NSP may have immune‐modulating and prebiotic effects and may be increasingly added to fish feed as modulators of fish health. We suggest that NSP is potentially (partly) digested by a wide range of fish species, especially by warm‐water species with a long gut adapted to feeding on plant matter, as these factors favour gut fermentation.

Exogenous enzymes and probiotics alter digestion kinetics, volatile fatty acid content and microbial interactions in the gut of Nile tilapia

“…As monogastric animals, fish lack NSP-degrading enzymes such as β-glucanases and β-xylanases, that allow digestion of the long polysaccharide chains present in NSP-rich plant-based ingredients, and therefore lack the ability to efficiently utilize nutrients from plant-based diets 7 . Commercially, to increase the nutrient availability and digestibility of the feeds, exogenous enzymes, such as phytase and xylanase, are commonly applied in the animal feed formulations, that catalyze the hydrolysis of phytic acid and polymeric carbohydrates, respectively 8 .…”

Diet type influences the gut microbiome and nutrient assimilation of Genetically Improved Farmed Tilapia (Oreochromis niloticus)

“…Assessing dietary carbon is important, as it encompasses essential nutrients such as carbohydrates and lipids [49]. These nutrients are vital for fish health as they play an important role in growth and metabolism [50,51]. In fish, fluctuations in dietary carbon are often reflected by their gastrointestinal microbiota [52].…”

Total and resistant starch from foodstuff for animal and human consumption in Costa Rica

“…In the same fashion, equine diets are commonly based in hay, cracked corn, oats and wheat middlings ( Harlow et al., 2016 ). Finally, starch-rich plant based ingredients such as soybean, linseed, canola, cottonseed, and sunflower meals, as well as wheat middlings, corn gluten, rice bran, barley, and rye have been all reported in various countries as a possible substitute for dietary fishmeal and oil in tilapia feeds ( Maas et al., 2020 ). However, alfalfa, barley, beet pulp, canola, cottonseed, oats and rye are not ingredients of widespread use in Costa Rica as feedstuff.…”