Effects of Hermetia illucens live larvae as environmental enrichment on poultry gut health

Hermetia illucens (HI) is a source of nutrients for poultry, both as live larvae and meal. Even if chitin (present in both HI forms) has been reported to negatively impact diet digestibility, it may also have beneficial effects on gut health. This study aimed to assess the effects of HI live larvae on the gut histomorphology of intermediate-growing chickens. Male chickens of 14 days of age (n=84, Label Naked Neck) were allotted to three dietary treatments (4 pens/treatment, 7 chicken/pen): control (C) fed a commercial diet; HI10 and HI20 (C + 10 and 20% of the bird expected daily feed intake of HI live larvae, respectively). In all the treatments, the C diet was distributed ad libitum. At day 82, 16 birds/treatment (4 birds/replicate) were slaughtered. Duodenum, jejunum, ileum, liver and Bursa of Fabricius were sampled and submitted to morphometric (villus height-Vh, crypt depth-Cd, villus width-Vw, Vh/Cd ratio, total absorptive area, and intestinal mucosa and muscular thickness) and histopathological analyses. Data were analysed by R software. The Vh, Cd, mucosal thickness and the total absorptive area were lower in HI20 than C and/or HI10 groups (P<0.05). Moreover, Vh, Vh/Cd, Vw, mucosa thickness and the total absorptive area decreased from duodenum to jejunum and/or ileum while muscular thickness increased proximo-distally (P<0.05). The diet did not influence the severity and distribution of inflammation in liver and cortical depletion of Bursa of Fabricius (P>0.05). However, the duodenum of HI20 group showed less inflammation than that of the other groups. In conclusion, despite the potential negative reduction in gut absorption surface of HI20 birds, the reduction in duodenum inflammation, as well as the overall maintenance of physiological gut development, suggest that HI live larvae can guarantee animal’s gut health. The CELLOWFEEP research received the support of Fondazione Cariplo (Italy).