An approach to converting raw animal waste to fish feed formulation: a case study for sustainable industrial waste management using acid silage methods

Abstract

Acid silage is a convenient method for converting raw poultry wastes (i.e., chicken offal) to fish feed ingredients. To investigate the potentiality of chicken offal for fish feed formulation; combination of two acids were used in the trail (90-days). The proximate compositions of raw offal contained 37.22 % moisture, 37.24 % protein, 18.80 % fat,19.04 % ash and 62.78 % dry matter; ensiled offal contained 25.02 % moisture, 47.31 % protein, 13.79 % fat, 13.45 % ash and 74.98 % dry matter; and post storage offal contained 23.05 % moisture, 44.33 % protein, 13.10 % fat, 12.75 % ash and 76.95 % dry matter. It took 13 days to convert raw offal into final product that was confirmed by physical observation in necked eyes (i.e., raw smell converted into pungent acidic; thick solid form liquefied; raw pink color converted to bright brownish and absence of microorganisms). No significant difference was observed during trail and storage period for all components as moisture, protein, fat, ash and dry matter. The pH value was found to be stable at 1.90 in 90-days storage period. These results suggest that chicken offal could be potentially used for aqua feed formulation that would be a cost effective means for industrial waste management.