Performance evaluation of chicken, cow and pig manure in the production of natural fish food in aquadams stocked with Oreochromis mossambicus

The main objective of this study was to characterize the ecological conditions that prevail after the application of chicken, cow and pig manure. Three treatments, chicken, cow, pig manure and a control were assigned to aquadams in a completely randomized design and each treatment was replicated three times. The aquadams were fertilized 2 weeks before the fish were stocked. One hundred Oreochromis mossambicus (mean weight +/- 40 g) were stocked in each aquadam. Water physico-chemical parameters (temperature, dissolved oxygen, pH, electrical conductivity, salinity, turbidity, ammonia, nitrite, total alkalinity as calcium carbonate, and phosphorus) were determined once a week for the duration of the experiment. Zooplankton and phytoplankton in the different treatments were enumerated once every 2 weeks. The relationship between phytoplankton communities and the water physico-chemical parameters were evaluated using canonical correspondence analysis (CCA). The CCA indicated that the physico-chemical variables which best explain the distribution of phytoplankton were carbonate alkalinity, pH, phosphate, potassium, nitrogen and dissolved oxygen. Phytoplankton abundance was highest in chicken manure because the optimum nutrient conditions for the growth of phytoplankton were found in this treatment. Zooplankton abundance was also highest in the chicken manure treatment. The control was associated with one phytoplankton taxa, Chlorella. The numerical contribution of the different food items in the stomachs of 0. mossambicus was determined. The diet of O. mossambicus was dominated by phytoplankton particularly Microcystis species. Total coliforms and Escherichia coli were used to assess the microbiological quality of the water in the different manure treatments. Chicken manure had the lowest total coliform and E. coli count. However, chicken manure had the highest Bacillus count. The implications of the microbial load in the chicken, cow and pig manure are discussed. (C) 2013 Elsevier Ltd. All rights reserved.