Can black soldier fly live larvae supplementation modify gut histomorphology of organic chickens?

The effects of insect meal on gut health have recently been reported in free-range and broiler chickens, but no data are available for organic intermediate growing chickens supplemented with black soldier fly (BSF) live larvae. Label naked neck chickens were reared from 21 to 82 days of age and randomly allotted into four groups (n= 240, 10 birds/pen, 6 replicates/treatment) according to bird gender (male-M and female-F) and larvae provision (Control-C and larvae-L). LM and LF groups received 10% supplementation of BSF live larvae, based on the average daily feed intake. At slaughter, samples of liver, spleen, bursa of Fabricius, and gut were collected from 60 animals (15 birds/treatment) and routinely processed for histomorphological examination. The following morphometrical parameters were evaluated on duodenum, jejunum, and ileum: villus height (Vh), villus width (Vw), crypt depth (Cd), Vh/Cd ratio, total absorptive area (TAA), mucosal, and muscular thickness. The observed histopathological findings were evaluated using a semi-quantitative scoring system (0: absent, 1: mild, 2: moderate, 3: severe). Morphometrically, Vh, TAA and mucosal thickness depended on sex, being greater in M than in F (P<0.05). Also, Vw was influenced by the interaction diet x sex, being greater in CM than in CF (P=0.016). Apart from Cd, all the evaluated morphometric indices depended on gut segment (P<0.001). Histologically, gut showed absent to moderate multifocal lymphoplasmacytic enteritis. Liver showed mild lymphoplasmacytic inflammation and absent to moderate multifocal vacuolar degeneration. Bursa of Fabricius presented absent to mild cortical depletion, while spleen did not show any alterations. Although the severity of all the observed lesions was not influenced by diet (P>0.05), liver degeneration depended on sex, being higher in F than in M (P=0.025). In conclusion, results showed that BSF live larvae provision did not impair gut and general health of organic chickens, assuring a physiological, sex-dependent gut morphological asset. Financial support for Poultrynsect project was provided by transnational funding bodies under the Joint SUSFOOD2/CORE Organic Call 2019.