A synergistic effect of dietary β-glucan and mannan oligosaccharide on growth performance, haematology, body composition, nutrient utilisation, and intestinal morphology in pompano, Trachinotus ovatus

Abstract

Pompano (Trachinotus ovatus) is an economically important aquacultural species. Intensive pompano cultivation faces numerous obstacles including pathogens, environmental stress, and the use of chemicals and drugs. It has been demonstrated that prebiotics, particularly mannan oligosaccharide (MOS) and β-glucan (BG), support growth and improve general health in a variety of species. However, studies on the effects of combining BG and MOS on the pompano performance are lacking. Thus, this study examined the influence of BG and MOS on pompano weighing 13.12±0.14 g for 8 weeks. The results revealed that fish fed BG, MOS, or BG+MOS had significantly increased growth rates (P≤0.001). The survival rate ranged from 97.3% to 99.4% without significant differences (P≤0.022). Fish in the control group had the highest coefficient of variation (CV) (30.78%), whereas fish in the MOS+BG group had the lowest CV (23.10%). RBC and WBC counts were higher in all supplemented-diet treatments (P ≤ 0.042). Among the supplemented diets, the combination diet resulted in the highest RBC and WBC count. The feed conversion ratios (FCR) of fish fed BG, MOS, or MOS + BG decreased significantly (P≤0.017). The FCR of fish fed both BG and MOS was lower than that of fish fed either BG or MOS (P≤0.032). Fish fed both BG and MOS had a higher feed conversion eficiency (FCE) than those fed only BG or MOS (P≤0.014). Protein content was the highest in pompanos fed BG + MOS and lowest in fish fed only BG or MOS. Dietary BG, MOS, or BG + MOS decreased the lipid content in pompano (P≤0.037). The protein efficiency ratio of pompano fed BG+MOS diet was significantly increased (P≤0.021). Villus length, villus width, and villous surface area increased in fish fed the supplemented diet, with the highest values observed in fish fed the combination of BG and MOS. It is recommended to offer pompano, T. ovatus, a mixture of 1 g kg β-glucan and 4 g kg mannan oligosaccharide to improve growth performance, hematology, feed and nutrient utilization, and gut morphology.