Solid state fermentation (SSF) of some fishery and agro- industrial wastes for animal feed production

Abstract

Four fishery wastes viz. mantis shrimp, trash fish, prawn waste and squid waste and two agro-industrial wastes viz, groundnut oil-cake and wheat bran were subjected to solid state fermentation for five days using one bacterial strain Bacillus licheniformis and Beauveria sp. The optimized fermentation conditions for SSF for the duration of five days for both Beauveria and B.licheniformis were: particle size of 2.0 mm for both Beauveria and B.licheniformis; moisture percentage of 70% for both Beauveria and B. licheniformis; inoculum size of 2 mL for Beauveria and 1 mL for B. licheniformis; pH 12.0 for Beauveria and 8.0 for B. licheniformis; temperature 28°C for Beauveria and 35°C for B. licheniformis. In fermentations with B. licheniformis dry matter losses ranged from as low as 4% in groundnut oil cake to as high as 16% in mantis shrimp and were comparatively lower in fermentation with Beauveria sp. (range 6.13% in trash fish to 13% in wheat bran). Protein contents of all the substrates increased upon fermentation with both B. licheniformis and Beauveria. Mantis shrimp recorded the highest increase in protein content of 20.41± 3.23 upon fermentation with B. licheniformis followed by prawn waste where an increase of 18.00 ± 2.53% in protein content was obtained. In other substrates protein ranged from between 9% to 13.08%. Beauveria also recorded an increase in protein content after fermentation but this was lower in comparison. A lot of variation was obtained in fiber content of substrates upon fermentation with B. licheniformis and Beauveria sp. Mantis shrimp, prawn waste and ground nut oil cake all recorded a decrease in fiber content after fermentation. Excepting in the case of wheat bran which recorded an increase in ash contents of 4.36 ± 0.97% and 3.00 ± 1.04% respectively upon fermentation with both B. licheniformis and Beauveria sp all the other substrates showed an increase in ash content ranging between 2% to 6.06% upon fermentation with B. licheniformis while a decrease was recorded in most substrates upon fermentation with Beauveria. Fat content was negligible in case of squid waste while mantis shrimp and groundnut oil cake failed to record any change upon fermentation with Beauveria sp. All other substrates fermented with both B. licheniformis and Beauveria sp. recorded a decrease ranging from 1% to 4% after fermentation. Results show that SSF is a suitable process for the utilization of these