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

Abstract

Six iso-nitrogenous (350 g protein kg )1 ) and iso-caloric (4100 kcal kg )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 ± 0.06 g) for 60 days in triplicate tanks (30 fish per tank). In all probiotic-supplemented diets, the probiotic concentration was maintained at 10 11 cfu kg )1 feed. After 60 days 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 (0 day 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 30 days of culture of fish and thereafter remained constant. KEY WORDS

Fish Nutrition and Current Issues in Aquaculture: The Balance in Providing Safe and Nutritious Seafood, in an Environmentally Sustainable Manner

“…Probiotics are live microbial organisms, non-pathogenic and non-toxic, which beneficially affect intestinal microbial products, reduce gut pH and release chemicals with bactericidal effects on other microbial populations, thus improving the immune response. The improvement in innate immunity in the fish helps against pathogenic bacteria, as well as against environmental stressors [54]. One of the major bottlenecks in the industry is high mortality during larval first feeding.…”

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“…However, during early developmental stages, it shows high mortality (70-80%) and poor growth rate. These factors hamper the availability of quality seed (Mohapatra et al, 2012) and expansion of the production of this species (Jha et al, 2015), consequently causing an economic loss (Edwards, 2013).…”

Digestive Enzyme Activities in Different Size Groups and Segments of the Digestive Tract in Labeo Rohita (Day, 1878)

“…Though digestive enzyme activity has been estimated in the gastrointestinal tract of Indian major carps [8][9][10][11][12], there is no literature on their activities in different size groups and segments of the digestive tract. Rohu shows a clear dietary preference to certain plant and animal protein diets.…”