Conversion of nutrients from pig feces and food waste by the black soldier fly: Preliminary results

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    Abstract

    The conversion of nutrients from two substrates by the black soldier fly was examined in a preliminary trial as commissioned by Millibeter, a company that seeks to make raw materials for industry and agriculture from waste. The substrates were fresh solid sow feces collected from the slatted floor (A) and mixed food waste consisting of vegetables, fruits and processed food (B). Two identical bioconversion units were constructed from 300 L-iron tippers (144x68x58 cm), that were sealed and equipped with one ball valve opening for feed supply and two smaller openings for aeration. The tippers were placed at the entrance of a pig barn with no extra heating. A 24-days-experiment (July, 2013) started with 75-100g larvae. Increasing amounts of substrate were daily added, totaling 45 kg of substrate per unit. At day 26, substrate and larvae were weighed, larvae were then separated from the substrate by wet sieving, were rinsed, dried and weighed. Pooled substrate sampled during cultivation and larvae samples were dried and ground. The substrate was analysed for dry matter (DM), crude protein (CP), crude fat (CFat), crude fibre (CF) and crude ash (CA) and the other carbohydrates (CH) were calculated by difference. The same analyses were carried out on the larvae samples except CF, which was considered to equal zero. The feces contained 20.2% DM, of which 15.3% CP, 8.3% CFat, 20.1% CF, 17.8% CA and 38.6% CH. The food waste contained 18.3% DM, of which 19.0% CP, 22.2% CFat, 8.6% CF, 9.3% CA and 40.9% CH. Larvae yielded 0.76 and 1.80 kg DM on pig feces and food waste, respectively. Larvae from A and B contained 30.6 and 36.1% DM, of which 38.4 and 34.0% CP, 32.4 and 47.2% CFat, 16.7 and 6.8% CA and 12.5 and 12.0 % CH, respectively. The conversion rate (nutrients in larvae/nutrients in substrate fed) in A vs. B amounted to 8.4 vs. 21.9% for DM, 22.2 vs. 34.3% for CP, 34.6 vs. 40.6% for CFat, 8.3 vs. 14.0% for CA and 2.9 vs. 5.6% for CH. The main conclusions are: (1) food waste clearly is a better substrate than pig feces, (2) conversion of crude fat is better than that of crude protein, (3) and conversion of crude ash and particularly carbohydrates is very low.
    Translated title of the contributionOmzetting van nutriënten uit varkensmest en voedselafval door de zwarte soldatenvlieg: Voorlopige resultaten
    Original languageEnglish
    Number of pages1
    Publication statusPublished - May-2014
    EventInternational Conference Insects to Feed the World - Ede, Netherlands
    Duration: 14-May-201417-May-2014
    http://www.wageningenur.nl/nl/show/Insects-to-feed-the-world.htm

    Conference

    ConferenceInternational Conference Insects to Feed the World
    CountryNetherlands
    CityEde
    Period14/05/1417/05/14
    Internet address

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