Effect of waste decomposer- pure microbial strains obtained from desi cow dung on the growth and performance of genetically improved farmed tilapia (Oreochromis niloticus)

The effects of waste decomposer (pure microbial strain obtained from desi cow dung) and raw cow dung on the growth and production performance of genetically improved farmed Tilapia (GIFT) were evaluated in nine earthen ponds at Cholamadevi, Ariyalur for a period of 120 d. Three treatments namely T1 (raw cow dung), T2 (pure microbial strains) and T3 control (with no fertilization) with three replicates were tested. GIFT was used as experimental species and stocking density was 8 fishes/m². The range of water quality parameters were found to be within the production range and had no significant (P>0.05) difference among the treatments. However, significant difference (P<0.05) was observed in case of weight gain and total production among the treatment. The highest mean weight (g) gain was obtained in T2 (235.5±0.42) followed by T1 (220.8±4.37) similarly the highest production (kg/ha/120days) was obtained in T2 (2796.57 kg) followed by T1 (2649.6 kg). The present study showed that the growth and production performance of GIFT were higher in T2 compared to other treatments. Though, no significant different was observed among T1 and T2 in growth and production performance, the use of pure microbial strain in form of waste decomposer, showed better economic impact in form of high BC ratio and less FCR compared to that of T1. Hence, it could be a better alternative for farmers who lack livestock for production of cow dung. Since direct microbial strain were used for fertilization, the time required for growth of phytoplankton was also reduced and growth of the good microbial organism is also enhanced causing better immunity and feed conversion in fishes reared in this pond. Further study should be needed to evaluate the use of pure microbial strains in polyculture system of carp fish which is also predominately practiced in this district