The effect of fly maggot in pig feeding diets on growth performance and gut microbial balance in Ningxiang pigs

: Fly maggot meal has been regarded as one of the substitutes of fish meal and soybean meal in pig feed. However, its effects on pig growth performance and faecal micro-organism remain unclear. The purpose of this study was to investigate the effect of dietary fly maggot meal on fattening performance, plasma indices related to gut hormones, immunity and faecal microbial communities composition of finishing pigs. A total of 40 Ningxiang fattening pigs were randomly allocated to two dietary treatments and pigs in each group were arranged by control group (CK) diet or 8% maggot meal group (MMG) diet for 45 days respectively. Growth performance, indices of gut hormones and immunity in plasma were evaluated. Microbiota composition in faeces was determined using 16S rDNA Amplicon Sequencing. The results showed that dietary MMG did not affect gut hormones and immune proteins in the trial compared with CK group (p > .05). However, dietary MMG significantly increased average daily gain (ADG). The population of the Firmicutes in MMG treatment was increased, while the percentage of the Bacteroidetes was decreased (p < .05). In particular, the number of Clostridiales related to hydrolyzed sugar and protein were increased (p < .05). It can inhibit the growth of harmful intestinal bacteria, promote the proliferation of beneficial bacteria and effectively improve the ability of digestion and absorption of nutrients. In conclusion, a diet containing 8% MMG changed the proportion of intestinal micro-organisms in finishing pigs, especially the higher richness of Firmicutes, and promoted the fattening ability of pigs to a certain extent. These changes should benefit finishing pig production during fattening period.