Effects of a commercial feed additive (Sanacore®GM) on water quality, productive performance and blood profile of gilthead seabream (Sparus aurata)

Abstract

The present study evaluated the effects of the inclusion of commercial feed additive (Sanacore® GM; SAN) in diets on growth and productive performance, digestive enzymes, intestinal microbiota, intestinal histomorphometry and blood profile of gilthead seabream (Sparus aurata). For this purpose, four diets containing 0.0% (the control), 0.1%, 0.2% and 0.4% SAN were formulated and offered to triplicate groups of fish (20–23 g) reared in cages (30 × 10 × 3 m) for ten weeks. Water quality parameters were regularly monitored during the experimental period. No marked variations (p > 0.05) were observed in water temperature, dissolved oxygen and pH values; meanwhile, substantially decreases in unionized ammonia and nitrite levels were specifically detected at the treatment of 0.4% SAN. Feeding the fish on SAN‐supplemented diets confirmed significant modulations in fish growth and production, haemato‐biochemical profile, intestinal microbiota and intestinal histomorphometry. Fish growth, production and feed utilization indices extensively multiplied alongside with the increase in dietary SAN levels achieving their optimum values at the treatment of 0.4% SAN in contrast to the control group (0% SAN). Intestinal α‐amylase, lipase and proteases activities were notably greater in fish fed with SAN‐supplemented diets in particular at the 0.4% SAN diet. Feeding gilthead seabream on SAN‐containing diets markedly increased red blood cell counts, haemoglobin level and haematocrit per cent mainly at the diet of 0.4% SAN. Compared with the control group, highest values of serum total protein, albumin and globulin accompanied with lowest values of alanine and aspartate aminotransferase were significantly recorded in fish fed on the 0.4% SAN diet. Intestinal microbiota were additionally modulated due to SAN administration to gilthead seabream. However, marked reductions in counts of Vibrio sp. and Escherchia coli alongside with high Bacillus sp. counts were obtained in fish mid‐intestine mainly at the 0.4% diet. Feeding gilthead seabream on SAN‐enriched diets confirmed higher villi length/width, absorption area and crypt depth than the control group with optimal values at the 0.4% SAN diet. According to the outcomes observed in this study, the SAN administration to gilthead seabream, especially at the 0.4% level led to considerable enhancements in overall growth and production performance via improving the secretion of digestive enzymes and prompting the intestinal morphometry and beneficial microbiota.