Bio-conversion rate and optimum harvest intervals for Daphnia carinata using digested piggery effluent and Chlorella vulgaris as a food source

Abstract

The bio-conversation rate of Daphnia carinata fed with Chlorella vulgaris grown on digested piggery effluent at three different feeding rates was determined and a 3, 4 and 5 day (d) harvest interavl strategy was investigated. A significant difference (P = 0.03) in the feeding rate against mean total populations was found among treatments. The increase in the amount of algae fed accelerated the production rate, and the population density peaked faster in the high C. vulgaris fed treatment. The bio-conversion rate (BCR) calculated from the experiment indicates that for every 10000 mg of C. vulgaris fed there was an increase of 437.9 mg of D carinata proudced. A significance difference (P = 0.017) in biomass production among the different harvest interval treatments was observed. The 3-d harvest interval produced 4.68 g of D. carinata followed by 5.15 g in the 4-d and 3.75 g in the 5-d harvest interval treatment. This study also indicates that 2 stage digested piggery effluent is a suitable culture medium for D. carinata.