No abstract

This study aimed to determine the protein content and the ratio of meat that can be added to the diet of black soldier fly (BSF) larvae for the sustainable recycling of food waste using insects. We conducted experiments feeding refined diets to BSF larvae with adjusted protein content and diets with minced pork, and analyzed the correlations between dietary nutrients and larval weight gain, mortality, and pre-pupal rate. The nutrient that was positively correlated with increased larval body weight and pre-pupal rate in both experiments was nitrogen-free extract (NFE). Diets with high concentrations of minced pork showed higher mortality of BSF larvae and were negatively correlated with dietary NFE content. It has been suggested that BSF larvae have reduced body weight and survival due to excessive protein and fat in their diet. Depending on the raw material and ratio of food waste, it may be necessary to adjust dietary protein and fat contents before treatment. The results of this study suggest that the NFE content of a larval diet influences the larval weight gain, mortality, and pre-pupal rate of BSF larvae in a great extent, a finding that has not been reported by previous studies.

This study investigated the effects of bamboo powder as an alternative feed for rabbits. The normal hay diet of rabbits was replaced with bamboo culm powder (10% and 20%) and fed to the rabbits until they were 90 days old. The blood samples were collected when the rabbits were 46, 66, and 90 days old to assess the effects of bamboo powder on blood parameters. The organs and intestinal contents were harvested at the age of 90 days, and the functions and morphologies of different organs were evaluated. The concentration of short-chain fatty acids (SCFAs) and the composition of microbiota in the cecum were measured. Substituting bamboo powder did not affect the growth, hematology profile, intestinal morphologies, and cecum SCFA concentration in rabbits. In contrast, it significantly altered the cecum microbiota composition, particularly the abundance of Ruminococcus and Bacteroides related to fiber degradation and Tyzzerella spp., associated with large intestine inflammation. These findings suggest that the substitution of hay with bamboo powder in rabbit diets does not negatively affect the overall health of rabbits and could be considered an alternative feed for rabbits; nevertheless, the protein and lipid deficiency in the bamboo powder should be taken into account.

Feeding laying hens with black soldier fly larval (BSFL) meal improves their performance. However, the beneficial mechanism of BSFL meals in improving the performance of laying hens remains unclear. This study investigated the effects of the BSFL diet on liver metabolism, gut physiology, and gut microbiota in laying hens. Eighty-seven Julia hens were randomly assigned to three groups based on their diets and fed maize grain-and soybean meal-based diets mixed with either 3% fish meal (control diet), 1.5% fish and 1.5% BSFL meals, or 3% BSFL meal for 52 weeks. No significant differences were observed in biochemical parameters, hepatic amino acid and saturated fatty acid contents, intestinal mucosal disaccharidase activity, and intestinal morphology between BSFL diet-fed and control diet-fed laying hens. However, the BSFL diet significantly increased the abundance of acetic and propionic acid-producing bacteria, caecal short-chain fatty acids, and modified the caecal microbial pathways that are associated with bile acid metabolism. These findings indicate that consuming a diet containing BSFL meal has minimal effects on plasma and liver nutritional metabolism in laying hens; however, it can alter the gut microbiota associated with short-chain fatty acid production as well as the microbial pathways involved in intestinal fat metabolism. In conclusion, this study provides evidence that BSFL can enhance enterocyte metabolism and gut homeostasis in laying hens.

Olive mill wastewater (OMW), a major by-product of the olive oil production industry, is rich in polyphenolic compounds that impart health benefits to several animals. Here, we evaluated the effects of OMW addition on the nutrients, quality, and bacterial composition of fermented total mixed ration (TMR). Different amounts of OMW (0%, 5%, 10%, and 20% in fresh matter) as a substitute for water were mixed with the formulated TMR and fermented for 4 weeks. At the initial stages of fermentation, OMW significantly altered the dry matter, pH, and lactic acid content; however, it had minor effects on most macronutrients, quality parameters, and bacterial flora in the final TMR product. OMW (10%) supplementation improved the polyphenolic compound content in the fermented TMR. However, OMW (10% and 20%) increased lipid levels beyond the recommended level of 3% in cow diets. OMW supplementation did not affect the microbial composition of TMR, except for an increased abundance of Weissella. These findings suggest that supplementation of 5–10% OMW improves the quality parameters of TMR without affecting the nutrient composition of fermented TMR. OMW can be used in cow feed; however, further studies involving feeding trials are needed to validate the effects of OMW on cows.