Use of different microbial probiotics in the diet of rohu, Labeo rohita fingerlings: Effects on growth, nutrient digestibility and retention, digestive enzyme activities and intestinal microflora

Six iso-nitrogenous (350g proteinkg ^-1) and iso-caloric (4100kcalkg ^-1) diets with or without probiotics supplementation namely T ₁ (Basal feed (BF) without probiotics; control), T ₂ (BF+Bacillus subtilis and Lactococcus lactis), T ₃ (BF+L. lactis and Saccharomyces cerevisiae), T ₄ (BF+B. subtilis and S. cerevisiae), T ₅ (BF+B. subtilis, L. lactis and S. cerevisiae) and T ₆ (BF+heat-killed bacteria of B. subtilis, L. lactis and S. cerevisiae) were fed to Labeo rohita fingerlings (6.0±0.06g) for 60days in triplicate tanks (30 fish per tank). In all probiotic-supplemented diets, the probiotic concentration was maintained at 10 ¹¹cfukg ^-1 feed. After 60days of culture, the fish fed combination of three probiotics at equal proportion (T ₅) had higher (P<0.05) growth, protein efficiency ratio, nutrient retention and digestibility and lower (P>0.05) feed conversion ratio over other treatment groups. Total heterotrophic bacterial population in intestine was drastically reduced on 15th and 30th days of sampling than the initial value (0day of sampling) for T ₃, T ₄ and T ₅ groups. Except T ₆, the gut colonization of respective probiotics, which were supplemented through the diets, was also increased up to 30days of culture of fish and thereafter remained constant.