International Journal of Aquaculture, 2016, Vol.6, No.21, 1
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and growth performance and significant increases in trypsin and amylase activities in rainbow trout fed fermented
Saccharomyces cerevisiae
. Mona et al. (2015) observed significant increase in the growth of African catfish
(
Clarias gariepinus
) fed yeast through diet. Gumus
et al. (2016) who replaced fishmeal in the practical diet of
goldfish with graded levels of brewer’s yeast recorded higher weight gain, SGR, FCR and PER with 35% yeast,
compared to other diets. Supplementation of diet with probiotics significantly improved growth performance, feed
utilization and survival of
Channa striata
fingerlings (Munir et al., 2016).
Feed conversion efficiency was better in the treated groups compared to the control; the best conversion was
obtained under 2 g treatment. This must have been the result of better utilization of nutrients. The highest RNA:
DNA ratio and VSI were recorded in 2 g G-pro treated fish, reflecting higher metabolic activity. The higher
RNA/DNA can be correlated with increased protein synthesis. RNA: DNA ratios have usually been related to the
tissue growth rate (Perago´n et al., 2000). VSI and HSI are indicative of food value (Keri et al., 2014). Feeding
probiotics had a positive influence on these body indices in
Channa striata
fingerlings (Munir et al., 2016).
Digestibility of protein and fat improved with the addition of G-Pro. This can be attributed to higher digestive
enzyme activity. Amylase activity was higher in the treated fish with the exception of the 1
st
intestinal segment in
which the control showed higher activity. Total amylase activity was higher in the proximal end of the intestine in
all the groups as reported in catla, rohu and mrigal by Dhage (1968). Improved protease activity was seen in the
treated fish, except in the 2
nd
intestinal segment of fish from 2 g and 4 g treatments. Lipase activity was higher
only in the pancreas of fish fed 1 g and 2 g G-Pro diets. These findings indicate that the digestive process was
positively influenced by the feed additive. Activity of digestive enzymes can be correlated with the nature and
composition of the food consumed (Deguara et al
.
,
2003). The digestion of food and absorption of nutrients
depends on the availability and efficiency of digestive enzymes (Furne et al., 2005). Probiotics are known to aid
digestion by exoenzyme supply and establishment of beneficial microflora in the digestive tract (Sankar et al.,
2016). A study conducted by Balcázar et al. (2006) suggested that probiotics have a beneficial effect on the
digestive processes of aquatic animals because probiotic strains synthesize extracellular enzymes such as
proteases, amylases and lipases as well as provide growth factors like vitamins, fatty acids, and amino acids.
Therefore, nutrients are absorbed more efficiently when the feed is supplemented with probiotics (Haroun et al.,
2006). It has been reported that the probiotic yeast
Debaryomyces hansenii
HF1 secretes amylase and trypsin
enzymes that aid digestion in sea bass (
Dicentrarchus labrax
) larvae (Tovar et al., 2002). Hunt et al. (2014)
reported improved digestive enzyme activity and proximate nutrient composition in trout juveniles fed diets
containing yeast based nucleotides.
Protein, fat and ash content of fish carcass was significantly affected in 1 g and 2 g G-pro treatments that recorded
significantly higher growth, reflecting increased protein and fat deposition and a decline in ash level in the muscle,
following treatment with the feed additive. Changes in protein and lipid content in fish body could be linked with
changes in their synthesis, deposition rate in muscle and/or different growth rate (Abdel-Tawwab et al., 2006).
Abdel-Tawwab et al. (2008) and Mona et al. (2015) reported that yeast supplementation significantly affected the
whole-fish body composition in Nile tilapia and African catfish respectively. Biochemical composition of fish
muscle is influenced by many factors, primarily the diet (Zietler et al., 1984).
From the present findings, it could be concluded that G-Pro is useful at levels of 1 g and 2 g/kg diet for enhancing
production performance of common carp. Using this probiotic through diet could result in enhancing economic
efficiency of fish farming.
Acknowledgement
We sincerely thank the Dean, College of Fisheries, Mangalore for the research facilities.
References
Abdel-Tawwab M., 2012, Interactive effects of dietary protein and live bakery yeast,
Saccharomyces cerevisiae
on growth performance of Nile tilapia,
Oreochromis niloti
cus (L.) fry and their challenge against
Aeromonas hydrophila
infection, Aquaculture International, 20: 317-331
