The present work, herein, studied the effects of corncob-derived xylooligosaccharides (CDXOS) and Lactobacillus plantarum CR1T5 (LP) integrated into fish diets (diet 1 (0-control), diet 2 (10 g kg-1 CDXOS), diet 3 (108 CFU g-1L. plantarum CR1T5), diet 4 (10 g kg-1 CDXOS +108 CFU g-1L. plantarum CR1T5)) on growth performance, innate immune parameters, and disease resistance of Nile tilapia (Oreochromis niloticus). Fingerlings, with average mean weight of 4.97 ± 0.04, were randomly distributed into 16 glass tanks (20 fish per tank) for 12 weeks. Growth performance, skin mucus, and serum immune parameters were evaluated at the conclusion of the experiment. Eight randomly selected fish were used for challenge test against Streptococcus agalactiae. The results indicated that fish fed CDXOS and LP had significantly improved final weight (FW), weight gain (WG), specific growth rate (SGR), and feed conversion ratio (FCR). However, no significant difference in survival rate was observed between specimens fed the supplemented diets and the control. Regarding skin mucus, the dietary inclusion of CDXOS and LP significantly increased lysozyme and peroxidase activities compared with the control (P < 0.05). Similarly, significant increases in serum lysozyme, peroxidase, alternative complement, phagocytosis, and respiratory burst activities were observed in the fish fed the supplemented diets. However, no significant differences were found in these parameters between fish fed CDXOS and LP diets. For the challenge test, diet 4 produced a higher relative percentage of survival (RPS) and resistance to S. agalactiae than fish from the other experimental groups (P < 0.05). The results suggested that CDXOS and L. plantarum CR1T5 are viable considerations for potential feed-additive sources.
Keywords: Corncob; Growth performance; Immune response; Lactobacillus plantarum CR1T5; Nile tilapia; Streptococcus agalactiae; Xylooligosaccharides.