Department of Agricultural, Forest and Food Sciences, University of Turin, Largo Paolo Braccini 2, 10095, Grugliasco (TO), Italy.
Department of Agricultural, Forest and Food Sciences, University of Turin, Largo Paolo Braccini 2, 10095, Grugliasco (TO), Italy.
Animal. 2024 Aug;18(8):101238. doi: 10.1016/j.animal.2024.101238. Epub 2024 Jul 2.
Rearing scale may influence black soldier fly (BSF) larvae traits when they are fed on a single diet, but different feeding substrates have not been tested yet. This study evaluated the effects of wheat starch processing by-products-based diets on growth performance, bioconversion efficiency, and nutritional profile of BSF larvae reared in different scales. Four diets (D1 and D2 [isonitrogenous, isolipidic and isoenergetic]; D3 and D4 [displaying 1:1 and 1:2 as protein to carbohydrate ratios, respectively]) were tested at 3 rearing scales (4 replicate boxes/diet, with a constant volume [0.84 cm]/larva and feed [0.7 g]/larva): 1) small (S; 12 × 12 cm, substrate height: 4 cm, 686 6-day-old larvae (6-DOL)/box), 2) medium (M, 32 × 21 cm, substrate height: 7 cm, 5 600 6-DOL/box), and 3) large (L, 60 × 40 cm, substrate height: 7 cm, 20 000 6-DOL/box). Larval weight was recorded at the beginning of trial and every 4 days, and growth rate (GR), specific growth rate (SGR), feed conversion ratio (FCR), survival, bioconversion efficiency corrected for residue (BER), reduction rate (RR), and waste reduction index (WRI) calculated at the end of larval growth (frass DM ≥ 55%). Substrate pH, T and height were measured at the beginning, every 4 days, and end of trial. Larval proximate composition was analysed at the end of trial. Data were analysed by generalised linear mixed model (SPSS software, P < 0.05). The D1 larvae showed higher weight, GR, SGR and WRI (along with higher substrate T) than D2 at M scale, while increased SGR and FCR - as well as decreased survival, RR and WRI - were observed in D2 larvae at S scale (P < 0.05). Larval CP and ether extract (EE) contents were influenced by M and L scales only, being higher in D2 group than in D1 (P < 0.001). Differently, decreased ash was recorded in D2 larvae when reared at S and M scales, while L scale revealed higher ash in D2 group than D1 (P < 0.001). The D3 larvae displayed greater weight, SGR, survival, RR and WRI (along with greater substrate T) than D4 at M scale, with increased survival and substrate T being also highlighted in L scale (P < 0.05). The D3 larvae also showed lower DM and EE - as well as higher CP - than D4 at all the rearing scales (P < 0.001). In conclusion, D1 and D3 led to better BSF larval growth performance, bioconversion efficiency and nutritional profile mainly at M and L scales, as a consequence of their ability to facilitate larval aggregation and, in turn, allow achieving a higher substrate T.
在单一种类的饲料条件下，饲养规模可能会影响黑水虻幼虫的特性，但不同的饲养基质尚未经过测试。本研究评估了以小麦淀粉加工副产物为基础的饲料对不同规模饲养的黑水虻幼虫生长性能、生物转化效率和营养特性的影响。在三种饲养规模（4 个重复箱/饲料，每个幼虫的恒定体积[0.84 cm]和饲料[0.7 g]）下测试了四种饲料（D1 和 D2[等氮、等脂和等能]；D3 和 D4[分别显示蛋白质与碳水化合物比例为 1:1 和 1:2]）：1）小（S；12×12 cm，基质高度：4 cm，686 只 6 日龄幼虫[6-DOL]/箱），2）中（M，32×21 cm，基质高度：7 cm，5600 只 6-DOL/箱）和 3）大（L，60×40 cm，基质高度：7 cm，20000 只 6-DOL/箱）。试验开始时和每 4 天记录一次幼虫体重，在幼虫生长结束时计算生长率（GR）、特定生长率（SGR）、饲料转化率（FCR）、存活率、生物转化率校正残渣（BER）、还原率（RR）和废物减少指数（WRI）。在幼虫生长结束时（干粪 DM≥55%）分析基质 pH 值、温度和高度。在试验结束时分析幼虫的近似组成。数据通过广义线性混合模型（SPSS 软件，P<0.05）进行分析。在 M 规模下，D1 幼虫的体重、GR、SGR 和 WRI（以及较高的基质 T）均高于 D2，而 S 规模下 D2 幼虫的 SGR 和 FCR 增加，存活率、RR 和 WRI 降低（P<0.05）。CP 和乙醚提取物（EE）含量仅受 M 和 L 规模的影响，D2 组的 CP 和 EE 含量高于 D1（P<0.001）。不同的是，S 和 M 规模下 D2 幼虫的灰分减少，而 L 规模下 D2 组的灰分高于 D1（P<0.001）。D3 幼虫在 M 规模下的体重、SGR、存活率、RR 和 WRI（以及较高的基质 T）均高于 D4，L 规模下的存活率和基质 T 也有所增加（P<0.05）。D3 幼虫在所有饲养规模下的 DM 和 EE 较低，CP 较高（均 P<0.001）。总之，D1 和 D3 主要在 M 和 L 规模下导致更好的黑水虻幼虫生长性能、生物转化效率和营养特性，这是因为它们能够促进幼虫聚集，从而达到更高的基质 T。
