Xylooligosaccharide supplementation improved growth performance and prevented intestinal apoptosis in grass carp

Abstract

The purpose of this study was to confirm the efficacy of xylooligosaccharides (XOS) on the growth performance and intestinal apoptosis of on-growing grass carp Ctenopharyngodon idella (167.46 ± 0.61 g). Fish were separated into six groups, which were given six different types of diet (supplemented with 0.00%, 0.002%, 0.004%, 0.006%, 0.008% and 0.010% of XOS) for 60 days. Grass carp were challenged with Aeromonas hydrophila (6 days) after the growth experiment. To our knowledge, the present study is the first to report that appropriate XOS supplementation: (1) improved growth performance in fish and (2) attenuated apoptosis via the internal mitochondrial signalling pathways (JNK and p38MAPK/Cytochrome-c/caspase-9) in the proximal intestine (PI) and mid intestine (MI) and the external death receptor signalling pathways (p38MAPK/FasL/caspase-8) in the distal intestine (DI). Interestingly, XOS supplementation had no effect on the mRNA levels of factor-related apoptosis ligand (FasL) or caspase-8 in the PI and MI, Bcl-2 in the PI and JNK, caspase-9, Bax or Apaf-1 in the DI. Finally, appropriate levels of XOS supplementation based on the percentage of weight gain (PWG), feed intake (FI), and caspase-3, -8, and -9 activities in the MI were estimated to be 51.81, 51.61, 57.15, 57.90, and 55.36 mg/kg diet, respectively.