Single or combined effects of fructo- and mannan oligosaccharide supplements on the growth performance, nutrient digestibility, immune responses and stress resistance of juvenile narrow clawed crayfish, Astacus leptodactylus leptodactylus Eschscholtz, 1823

Abstract

Abstract A 126-day experiment was carried out under controlled conditions to compare the effects of mannanoligosaccharide (MOS) and fructooligosaccharide (FOS) at three levels (1.5, 3.0 and 4.5 g kg − 1 ) in the single diets and three levels (0.75, 1.5 and 2.25 g kg − 1 ) in the combined diets on the growth performance, nutritional efficiency indices, In vivo ADC of nutrients, digestive enzymes, hemolymph indices and finally, biological responses against 12-h air exposure and 48-h Aeromonas hydrophila exposure challenges of juvenile (10.56 ± 0.32 g) crayfish Astacus leptodactylus leptodactylus . The highest values of SGR (1.59% day − 1 ), VFI (3.80% body weight day − 1 ), survival rate (94.1%) and the lowest FCR (2.67) were observed in the juvenile crayfish fed the diet containing 2.25 g kg − 1 MOS and 1.5 g kg − 1 FOS. The significantly ( p − 1 MOS and 1.5 g kg − 1 FOS. The mean of In vivo ADC OM (73.47%), In vivo ADC CP (84.98%), In vivo ADC CF (83.79%) and In vivo ADC GE (82.77%) of the juvenile crayfish fed the diet containing MOS was higher than those of juvenile crayfish fed the diet containing FOS. The juvenile crayfish fed the diet containing 2.25 g kg − 1 MOS and 1.5 g kg − 1 FOS had the significantly ( p − 1 ) for amylase (8.21), lipase (7.3) and alkaline protease (7.5) and the mean (× 10 5 cell ml − 1 ) of hemolymph indices (× 10 5 cell ml − 1 ) including THC (107.14), HC (97.18), SGC (38.12) and LGC (47.36). After 12-h air exposure challenge, the juvenile crayfish fed the combined diets showed significantly ( p A. hydrophila injected crayfish fed the single diets containing MOS (20.1%) was significantly ( p − 1 MOS and 1.5 g kg − 1 FOS in the diet was considered optimum. It can be concluded that dietary MOS and FOS exerted positive effects on the growth performance, feed utilization and accelerated crayfish immune responses against air and bacterial exposure challenges.