Comparative efficacy of mannan-oligosaccharides from two yeast species fed alone or in combination with probiotic Bacillus subtilis ATCC 6633 to Catla ( Catla catla ) juveniles

Saccharomyces cerevisiae is the most commonly used source for mannan-oligosaccharides (MOS) in the animal feed industry. Recently, we proposed Wickerhamomyces anomalus SZ1 isolated and characterized from home-made curd that yield 33% higher MOS than S. cerevisiae as an alternative to the latter (Gupta et al. 2018 ). This report details the results of a 60-day performance feeding trial in Catla ( Catla catla ) fish aimed at evaluating comparative efficacy of MOS from W. anomalus (W-MOS) and S. cerevisiae (S-MOS) when fed at 0.4% rate solely or in combination with probiotic (PB) bacteria, Bacillus subtilis ATCC 6633 (10 6 CFU g −1 feed). One hundred and fifty juveniles were equally distributed in five groups, in triplicates, and were fed one of the five isocaloric and isonitrogenous diets viz. control, 0.4% S-MOS, 0.4% W-MOS, 0.4% S-MOS + PB and 0.4% W-MOS+ PB . Percent weight gain, specific growth rate (SGR) and food conversion ratio (FCR) at the end of experiment indicated that the growth performance of Catla fingerlings with dietary supplementation of 0.4% MOS (4 g kg −1 ) from either source was significantly better ( P < 0.05) than control fish, but further potentiation of effects was observed in W-MOS only indicating species-specific synergistic complementation of pre-probiotics. Packed cell volume was increased with 0.4% MOS feeding, which was further augmented when probiotic was co-fed ( P < 0.05). The modulation of activities of digestive (intestinal protease and amylase) ( P < 0.01) and metabolic (liver and muscle ALT, AST, LDH, MDH) enzymes ( P < 0.05) further supported the improved growth performance of fish. Body composition of fingerlings, at the end of feeding trial, fed 0.4% MOS from either source, alone or in combination with probiotic, was unaffected. It was concluded that MOS from W. anomalus is superior alternative to that from Saccharomyces cerevisiae (W-MOS) and can be used in feed industry along with probiotic in promoting better growth performances.