Chemical composition of Lucilia sericata larvae biomass when growing them on different nutrient media

In modern agricultural production, there is an increasing need for the efficient utilization of organic waste and the search for alternative protein sources for the feed industry. One promising direction is the cultivation of insects, particularly the larvae of the Lucilia sericata fly, on meat and fish processing waste. The larvae of this fly are capable of accumulating significant amounts of protein, fat, macro- and microelements, making them a valuable raw material for the production of feed additives. The aim of our study was to determine the effect of the composition of the nutrient medium (minced poultry intestines, liver, and fish) and temperature regime (20,0–21,0 °C and 24,0–25,0 °C) on the chemical composition of Lucilia sericata larval biomass. The experiment used three types of nutrient media, minced to a size of 2,8–3,5 cm, with a ratio of 0,5 kg of substrate per 0,2 g of two-day-old larvae. The study revealed that the chemical composition of Lucilia sericata larval biomass varied depending on the nutrient medium and temperature. The moisture content in the biomass did not undergo statistically significant changes, remaining within the range of 66,5–68,8 %. The highest total protein content was recorded in larvae grown on minced poultry intestines (17,1 % at 20,0–21,0 °C and 17,0 % at 24,0–25,0 °C). Meanwhile, the highest fat content was observed in biomass derived from liver (over 7 %), whereas intestines and fish substrates yielded statistically lower fat levels. Ash content also depended on the type of substrate: the highest value was recorded when using liver (6,32 % at 20 °C), and the lowest when using fish. The content of sulfur and phosphorus was highest in the larval biomass grown on liver, indicating the high nutritional value of this medium. In particular, sulfur content reached 0,6 g/kg and phosphorus 3,3 g/kg in this group. A decrease in temperature led to slightly higher levels of protein, fat, ash, and mineral elements. Thus, it has been proven that the chemical composition of Lucilia sericata biomass depends on both the type of nutrient medium and the temperature regime of cultivation. The highest nutritional value of the larvae was observed when they were grown on minced poultry liver at a temperature of 20,0–21,0 °C. These results can be used to optimize the cultivation technology of Lucilia sericata in order to produce high-quality protein feed additives while simultaneously reducing the volume of animal-derived organic waste.