This study was conducted to systematically assess and compare the fluctuations in crude protein (CP), crude fat (CF), and mineral content of staged (larva to adult) Drosophila (fruit fly) to that of a market-purchased black soldier fly larvae (BSFL) product. Results suggested that the relative CP content by dry matter ranged from 40.11% to 53.73% during Drosophila development, significantly higher (P < 0.001) than the 36.90% in BSFL. The relative CF was higher in BSFL (39.14%) compared to that of Drosophila (27.03-30.10%, P < 0.001). Although both insects contained sufficient levels of minerals to meet the dietary requirements of most animals, Drosophila overall possessed a lower content of iron, sodium, and calcium (P < 0.001) with a higher gross energy than the BSFL (P < 0.01). Comparative studies of amino acid (AA) and fatty acid (FA) profiles were further carried out among Drosophila larva (DL), pupa, and BSFL for their economic effectiveness. The AA spectra of insect larvae generally were similar except that the DL was higher in certain AA such as lysine (P < 0.01), which is an essential AA often critical for chicken growth. In contrast, the BSFL included more essential FA such as linoleic (C18:2, ω-6) and linolenic (C18:3, ω-3) acids (P < 0.01). To follow up, a husbandry trial was performed by allotting 120, 1-d-old, weight-matched, Arbor Acres broilers at random into treatment groups consisting of a low-protein diet background that contained ~20% CP supplemented with 4% BSFL and 4% or 8% DL. The average daily growth (ADG) and average daily feed intake (ADFI) of broilers, compared to the control low-protein diet, were significantly improved by feeding DL diets (P < 0.01), with better live and carcass weight and higher muscle pH (P < 0.001), which were positively correlated with the inclusion level of DL (P < 0.001). However, no differences between the control and 4% BSFL diet were observed for the performance parameters mentioned above. Moreover, all birds under our experimental setting exhibited a comparable feed conversion ratio (FCR) and were in a healthy status as indicated by the meat traits and hematological indexes within normal physiological ranges. Collectively, the findings in this study provide a theoretical basis for the further exploitation of Drosophila as potential dietary ingredients for feed production in order to meet the food challenge in the future.
Keywords: Drosophila; black soldier fly; broiler; dietary protein; insect larvae.
Insects are regarded as one of the most promising protein sources for feed production due to its high nutritional value and low environmental cost. The objectives of this study were to analyze the dynamic nutritional composition of Drosophila (fruit fly) at various developmental phases in parallel with a commercial black soldier fly larvae (BSFL) meal, as well as to determine the effect of diets with their inclusion on broilers. Results showed that Drosophila larvae possessed a higher crude protein and a lower crude fat content when compared to the BSFL product. In the feeding trial, the performance of broilers receiving Drosophila diets was remarkably improved, with no significant influence on bird metabolic status and meat quality, except the pH of breast and thigh muscles in Drosophila diet groups being higher than that of the control group, but still in the normal range. To sum up, Drosophila meal evaluated herein has a good nutritional composition and thereby elicits a beneficial impact on the growth performance and meat production of broilers, making it a potential dietary protein source for poultry.
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