Effect of traditional processing methods on chemical composition and in vitro true dry matter digestibility of the Mophane worm (Imbrasia belina)

Abstract

Effects of traditional processing methods on the nutritional value of Mophane worm (Imbrasia belina) were evaluated. Samples were degutted or not degutted. The worms were further subjected to either cooking for 1 h (remaining in boiling water for 45 min), hot ash roasted for 5–7 min or not treated (control). Treatment had an effect on the level of most minerals, on the in vitro true dry matter digestibility (IVTDMD) (P<0.001), crude protein (CP) and magnesium (Mg) (P<0.05). Fiber components, acid detergent insoluble nitrogen (ADIN) and manganese (Mn) and available CP (CPav) were not affected (P>0.05). Degutting had an effect on CP, fiber components, minerals, (P<0.001), ADIN, IVTDMD and Mn (P<0.01). Leaves from Mophane vegetation in the undegutted Mophane worm samples diluted levels of CP, ADIN, Zn, Mn and IVTDMD but increased the levels of ash, fibre components, Ca, and P. Mg and CPav were not (P>0.05) affected by degutting. There were no interactions (P>0.05) between treatment and degutting for ash CP, CPav, ADF, ADL, ADIN, P, Zn, Mn or Mg. An interaction was observed for NDF (P<0.01), Ca (P<0.001) and IVTDMD (P<0.05). A significant and negative correlation was observed between ADF and IVTDMD (r=−0.86, P<0.001). CP and IVTDMD were positively correlated (r=0.88, P<0.001). Therefore, it will not be necessary to degut Mophane worms destined for livestock feeding. High fibre levels in the undegutted Mophane worms would make it necessary to degut worms which are destined for human consumption. Given the scarcity of protein in Botswana it is important to evaluate locally available feed resources as potential livestock feeds.