Potential application and beneficial effects of a marine microalgal biomass produced in a high-rate algal pond (HRAP) in diets of European sea bass, Dicentrarchus labrax

Abstract

Microalgae have been used as live food in aquatic species. In recent years, the interest in microalgae has considerably increased, thanks to the evolution of production techniques that have identified them as an ecologically attractive aquafeed ingredient. The present study provides the first data about the effects of dietary inclusion of a microalgae consortium grown in a high-rate algal pond system on zootechnical performance, morphometric indices, and dietary nutrient digestibility as well as morphology and functionality of the digestive system of European sea bass, Dicentrarchus labrax. A dietary treatment including a commercial mono-cultured microalgae (Nannochloropsis sp.) biomass was used for comparison. Six hundred and thirty-six European sea bass juveniles (18 ± 0.28 g) were randomly allotted into 12 experimental groups and fed 4 different diets for 10 weeks: a control diet based on fish meal, fish oil, and plant protein sources; a diet including 10% of Nannochloropsis spp. biomass (100 g/kg diet); and two diets including two levels (10% and 20%) of the microalgal consortium (100 and 200 g/kg diet). Even at the highest dietary inclusion level, the microalgal consortium (200 g/kg diet) did not affect feed palatability and fish growth performance. A significant decrease in the apparent digestibility of dry matter, protein, and energy was observed in diets including 10 and 20% of the microalgal consortium, but all fish exhibited a well-preserved intestinal histomorphology. Moreover, dietary inclusion with the microalgal consortium significantly increased the enzymatic activity of maltase, sucrase-isomaltase, and ɤ-glutamil transpeptidase in the distal intestine of the treated European sea bass. Algal consortium grown using fish farm effluents represents an attempt to enhance the utilization of natural biomasses in aquafeeds when used at 10 % as substitute of vegetable ingredients in diet for European sea bass.

Impacts of Fortifying Nile Tilapia (Oreochromis niloticus) Diet with Different Strains of Microalgae on Its Performance, Fillet Quality and Disease Resistance to Aeromonas hydrophila Considering the Interplay between Antioxidant and Inflammatory Response

“…In the current study, after a 12-week feeding period on N. oculate and Schizochytrium and Spirulina species combination enriched with omega-3, we achieved our targeted goal concerning maximum fish production and an enhanced fillet quality with omega-3 (n-3) fatty acids. In accordance, dietary feeding on Schizochytrium species for Nile tilapia [ 11 ] and Nannochloropsis species for European sea bass [ 64 ] improved their growth rates to certain limits, while feeding of Nile tilapia in our study on a combination of selected microalgae enhanced the growth performance parameters of Nile tilapia more prominently, especially with increasing their inclusion levels (up to 3%). Besides, more efficient digestion due to higher digestive enzymes’ activities was detected in groups exhibiting improved growth-related parameters and those fed higher levels of microalgae mixtures, which came in the same line with the findings stated previously [ 65 , 66 , 67 , 68 , 69 ].…”

A commercial blend of macroalgae and microalgae promotes digestibility, growth performance, and muscle nutritional value of European seabass (Dicentrarchus labrax L.) juveniles

“…In contrast, previous studies reported no effects or even a reduction of intestinal area, or villus length and width in carnivorous fish fed diets supplemented with individual Ulva sp., Gracilaria sp., Chlorella sp., or Nannochloropsis sp. ( 41 , 54 , 94 , 95 ), or their mixtures ( 54 , 79 , 80 ). Fish fed the control diet (Algae0) had the lowest number of goblet cells.…”

The Potential of Marine Microalgae for the Production of Food, Feed, and Fuel (3F)

“…They observed an improvement in body weight, length, and survival rate by 35.75%, 21.17%, and 33%, respectively, compared to the control diet. Likewise, fishes fed with microalgal consortium manifested well-maintained digestive histomorphology because it can enhance the enzymatic activity of maltase, sucrase-isomaltase, and ɤ-glutamil transpeptidase in the distal intestine [125]. A recent study has demonstrated the benefits of using microalgae as a substitutive feed ingredient in dairy cattle diets [126].…”

“…is often utilized as feed for rotifers to improve its EPA content, Isochrysis sp. is used to enhance DHA content -glutamil transpeptidase in the distal intestine [125]. A recent study has demonstrated the benefits of using microalgae as a substitutive feed ingredient in dairy cattle diets [126].…”