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

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 225 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 (10.56 032 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 225 g kg(-1) MOS and 1.5 g kg(-1) FOS. The significantly (p < 0.05) highest PER (327), LER (3.45), EER (3.78), PPV (7135%), LPV (7325%) and EPV (8920%) were related to the diet containing 225 g kg(-1) MOS and 15 g kg(-1) FOS. The mean of In vivo ADCom (73.47%), In vivo ADCGp (84.98%), In vivo ADC.GF (83.79%) and In vivo ADCGE (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 i MOS and 1.5 g kg(-1) FOS had the significantly (p < 0.05) highest activities (U mg(-1)) for amylase (8.21), lipase (7.3) and alkaline protease (7.5) and the mean (x 10(5) cell m1(-1)) of hemolymph indices (x 10(5) cell ml(-1)) induding THC (107.14), HC (97.18), SGC (38.12) and LGC (4736). After 12-h air exposure challenge, the juvenile crayfish fed the combined diets showed significantly (p < 0.05) higher activities of PO, SOD, LYZ and NOS than those of fed the single diets. The mean survival rate of A. hydrophila injected crayfish fed the single diets containing MOS (20.1%) was significantly (p < 0.05) higher than those of fed the single diets containing FOS (15.9%) and control (11.6%). At the levels tested, 225 g kg(-1), MOS and 15 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. (C) 2014 Elsevier B.V. All rights reserved.