Fructooligosaccharide supplementation in diets for tropical gar ( Atractosteus tropicus ) juvenile: Effects on morphophysiology and intestinal barrier function

Abstract

Supplementary fructooligosaccharides (FOS) were evaluated on growth, survival, gut morphology, digestive enzyme activity and expression of intestinal barrier genes in tropical gar (Atractosteus tropicus). Four treatments were designed to include FOS (5, 10, 15 and 20 g/Kg) and were compared with a control (0 g/Kg) and the current commercial trout diet. Ten fish were stocked (0.25 ± 0.01 g and 4.2 ± 0.4 cm total length) per experimental unit by triplicate in a 45-day experiment. Fish fed with 5 and 10 g/Kg of FOS had the highest average weight and total average length. Fish fed 5 g/Kg FOS showed the best growth indexes (absolute weight gain: 2.16; specific growth rate: 4.96; and feed conversion rate: 1.23) and survival (96.66%) and also had the highest acid protease, chymotrypsin and leucine aminopeptidase activities. Fish fed 5 g/Kg FOS had a high absorption area and accumulation of lipids in the liver. Finally, relative overexpression of occluding (occ), nucleotide-binding oligomerization domain-2 (nod2) and mucin 2 (muc2) was detected in fish fed 10 and 15 g/Kg FOS. The supplementation between 5 and 10 g/Kg FOS in diets for A. tropicus juveniles could be beneficial for growth, digestive enzyme activities, gut morphology and intestinal barrier function.

Incorporation of Fructooligosaccharides in Diets Influence Growth Performance, Digestive Enzyme Activity, and Expression of Intestinal Barrier Function Genes in Tropical Gar (Atractosteus tropicus) Larvae

“…While acid protease activity was greater in fish fed with 2.5 g kg −1 FOS, chymotrypsin and lipase activities were higher in the control diet. Similar to these results, previous work with A. tropicus juveniles showed that fish fed with 5 g kg −1 FOS showed higher acid protease activities [13]. Acid proteases are more abundant in the stomach of carnivorous fish species [33].…”

“…In this study, we evaluated the expression of the mucus layer protein MUC-2. Our results showed that muc-2 relative expression was up-regulated in A. tropicus larvae fed with 7.5 g kg −1 FOS, according to [13], who reported that A. tropicus juveniles fed 10 and 15 g kg −1 FOS showed overexpression of muc-2. While [24] did not show any differences in the muc-2 expression with the supplementation of β-glucans in juveniles of A. tropicus.…”

“…Besides, positive effects have been observed in studies with juveniles of the same species, like [28], who proved that the supplementation of 2 g kg −1 MOS in A. tropicus juveniles increased weight gain, total length, specific growth rate, and protein efficiency ratio. In addition, [13] determined that the administration of 5 g kg −1 FOS to A. tropicus juveniles benefits its growth and the somatic indexes, weight gain, and specific growth rate. However, [24] determined that A. tropicus juveniles fed with different concentrations of β-glucans (up to 2 g kg −1 ) no-showed significant difference in growth performance.…”

“…Recent studies have reported that the use of FOS show a positive effect on growth, survival rate, and activity of digestive enzymes in several species, such as rainbow trout (Oncorhynchus mykiss) [9], Caspian roach fry (Rutilus rutilus) [10], blunt snout bream fingerlings (Megalobrama amblycephala) [11], starry sturgeon (Acipenser stellatus) [12], among others. In A. tropicus juveniles, 5-10 g kg −1 FOS inclusion improved the digestive capacity, growth, and survival [13]. However, the effect of FOS inclusion in the larval stage and on the intestinal barrier function has not been described.…”

Dietary Effects of Sodium Propionate Supplementation on Growth, Digestive Enzyme Activity and Immune System Gene Expresion of Tropical Gar Juveniles (Atractosteus Tropicus)

“…These results may be due to the action of organic acid salts which reduces pH in the stomach and intestine (Lee et al, 2015). Other studies in A. tropicus show increased activity of alkaline proteases, trypsin and chymotrypsin in sh fed with low concentrations of MOS and FOS (0 and 0.5%) (Nájera-Arzola et al, 2018; Sepúlveda-Quiroz et al, 2021). The activity of lipases and amylases were not modi ed between treatments, similar to the results reported by Nieves-Rodríguez et al ( 2018) when including B-glucans in diets for juveniles of A. tropicus.…”