Growth of black soldier fly larvae maintained on different organic substrates

Abstract

Black Soldier fly larvae (BSFL) meal is becoming a popular protein source to replace fishmeal from animal feeds. However, identification and access to suitable substrates on which BSFL can be grown rapidly to generate substantial volumes that can be used in feed formulation remains a challenge. In this study, brewery waste, rice, wheat, and maize bransand chicken droppings were the organic substrates tested for supporting growth, productivityandprofitabilityof BSFL. A one-month growth experiment for BSFL on different organic substrates was conducted. About 600 eggs were inoculated in 500g of each moistened organic substrate. The substrate was then changed after exhaustion,making a total of a kilogram of substrate used.The experiment was conducted at Kajjansi Aquaculture Research and Development Centre (ARDC)from the 21st of February, 2022 to the 15th of March, 2022. The first BSFL larvae recordings appeared after 6 days on brewery waste, rice, wheat and maize brans, and after 12 days on chicken droppings. For the first fifteen days after inoculation, the BSFL raised on maize bran had significantly higher body mass(0.25 ±0.006g), compared to those on brewery waste(0.17 ±0.003g) and chicken droppings, that were significantly the lowest (0.02 ±0.008g). Maize bran and rice bran showed the highest The increase in body mass per day (growth rate) was highest in the groups raised on maize bran (0.02±0.0015)and rice bran (0.03 ±0.0001); and lowest in the groups on brewery waste(0.02±0.0003) and chicken droppings (0.01±0.0003), for the first 9 days. Ultimately, maize and rice bran yielded maximum body mass of BSFL larvae. However, cost of producing a kilogram of BSFL (i.e., UGX 900) was lowest when brewery waste was used. The cost of producing a kilogram of BSFL (i.e., UGX 9300) was highest when maize bran was used because of the unit cost of the substrateas a kilogram costed 1000 shillings. Relatively a kilogram of brewery waste costed least (i.e., UGX 90) and gave an average mean body mass output of (0.17 ± 0.003 g)close to those in the three branswith the highest mean body mass output, making it more profitable than the rest of the organic substrates.