Effects of partially defatted larvae meal of Black Soldier Fly (Hermetia illucens) on caecal microbiota and volatile compounds of Muscovy ducks (Cairina moschata domestica)

The present study explored the effects of substituting maize gluten meal with increasing levels of partially defatted black soldier fly larvae meal (BSFLM) in Muscovy ducks’ diets on their caecal microbiota and organic volatile compounds. The ducks were divided into four groups, each receiving a diet containing 0%, 3%, 6%, or 9% BSFLM (HI0, HI3, HI6, and HI9, respectively). At slaughter (50 days of age), caecal samples were collected and analysed. The alpha diversity indexes were lower in the HI9 than in the HI0 and HI3 treatments that did not differ between them. Bacteroidetes in the HI0 and Firmicutes in the HI6 treatment showed a higher abundance than in the HI9 treatment. Faecalibacterium and Megamonas were more abundant in the HI6 than in the HI9 treatment. Abundance of Clostridium and unclassified Coriobacteriaceae were higher and lower, respectively, in the HI9 than in the HI0 treatment. Canonical discriminant analysis revealed that Faecalibacterium, unclassified Victivallaceae and Megamonas in relation to Ruminococcus would separate the HI6 and HI9 treatments, while unclassified Coriobacteriaceae in relation to Streptococcus and Faecalibacterium would distinguish the HI0 and HI3 from the HI6 and HI9 treatments. Eleven volatile compounds were more abundant HI9 than in the HI6 treatment. Five of them were negatively correlated with Faecalibacterium and two with Megamonas. These findings indicate that diets with 6% and 9% BSFLM alter the caecal microbiota in Muscovy ducks, while a diet with 3% BSFLM has no effect. The distinct abundance of several volatile compounds in the 6% and 9% BSFLM treatments suggests a relationship between their characteristic microbiota profile and those compounds that warrants further investigation.