In this study, a self-selected feed design was conducted for Japanese food wastes, considering the macronutrients (protein, lipid, carbohydrate) and six feed options and three options for vegetable wastes, and performance was compared with commercial diet to determine the usefulness of the feed design method and the possibility of using food waste in Japan were examined by comparing the performance of the feed design method with commercial diet. Data on self-selection diet design for crickets at different growth stages were obtained to determine the differences in feed consumption rates and nutrient requirements among stages. The results showed that it is possible to achieve cricket weight and feed conversion efficiencies (0.5-0.8) comparable to those of commercial diets using food residues when macro-nutrients are considered, and abundant options are provided. On the other hand, the use of only vegetable wastes resulted in lower cricket weight and higher feed conversion efficiency (0.8-1.4). Based on feed consumption rates, bread bran, rice bran, and fish meal were found to be suitable feeds among Japanese food waste for production in all growth stages, while bean curd and sake less were found to be suitable for production in some growth stages. Data obtained from self-selections separated by growth stage revealed that the percentage of feed consumption varied greatly among growth stages, being about 50-68% in the late growth stage. Percentages of macronutrients and micronutrients were also found to vary by growth stage. Protein percentages were found to be higher in the second week after hatching. Lipids were highest in the first week and decreased thereafter. Crude fiber was lowest in the fourth week. Ash content did not change significantly at all stages. This research is the first attempt at self-selection of crickets in different growth stages, and the data obtained can contribute to feed design.
Partially hydrolysed guar gum (PHGG) is a water-soluble dietary fibre that is non-digestible in the upper gastrointestinal tract. It is believed that PHGG benefits the health of hosts by altering the colonic microbiota and stimulating short-chain fatty acid (SCFA) production. However, it remains unclear which bacteria ferment PHGG in the human large intestine. In this study, the effect of PHGG on faecal bacteria was analysed to specify the bacteria that contribute to the fermentation of PHGG in the human large intestine. Ten healthy volunteers consumed PHGG (6 g/day) for 2 weeks. Faeces were collected at 2 weeks prior to consumption, at the end of 2 weeks of consumption, and 2 weeks after consumption of PHGG. Bacterial DNA was extracted from these collected faeces and subjected to real-time PCR using bacterial group- or species-specific primers. The copy number of the butyryl-CoA CoA-transferase gene and the 16S rRNA gene copy numbers of Bifidobacterium, the Clostridium coccoides group, the Roseburia/ Eubacterium rectale group, Eubacterium hallii, and butyrate-producing bacterium strain SS2/1 were significantly increased by the intake of PHGG. Other bacteria and bacterial groups were not significantly influenced by the intake of PHGG. It was believed that the Roseburia/E. rectale group bacteria, Bifidobacterium, the lactate-utilising, butyrate-producing bacteria, E. hallii and bacterium strain SS2/1, would contribute to the fermentation of PHGG in the human large intestine. PHGG may benefit health by stimulating Bifidobacterium and butyrate-producing bacteria in the human large intestine.