Effect of pig dung on water quality and polyculture of carp species during winter and summer

摘要

The effect of pig dung, as pond manure [at 18 and 36 t ha(-1) yr(-1)] and as fish feed ingredient [replacing traditional diet composed of solvent extracted rice bran and mustard cake (1:1) at 25, 50, 75 and 100% levels], was observed on water quality, pond productivity and survival and growth of carp in polyculture system during winter (12-18 degreesC) and summer (18-36 degreesC) months. The studies on water quality parameters viz pH, dissolved oxygen and alkalinity revealed that pig dung even at higher levels (both as manure and/or as feed ingredient) did not deteriorate the quality of water, as all the water parameters remained within the optimum ranges required for carps. The nutrient (phosphates and nitrates) status of water was significantly better in ponds receiving pig dung as pond manure at 36 t ha(-1) yr(-1). Pond productivity in terms of plankton production (phyto and zooplankton) was also significantly higher in nutrient rich water (36 t ha(-1) yr(-1)) both during winter and summer. Further, in all the ponds (including control) phytoplankton levels were significantly higher during winter and zooplankton was higher during summer. The studies revealed 100% survival of all the fish species in all the treatments. During winter, the growth of carp was higher in treatments where pig dung was used as feed ingredient (at 25% level), whereas during summer growth was higher where pig dung was used either as pond manure and/or as feed ingredient (at higher levels). Further, among carps, the growth of Indian major carps viz Catla catla, Labeo rohita and Cirrhina mrigala was higher during summer and that of exotic carps viz Cyprinus carpio and Ctenophayrengodon idella was higher during winter.