Ground pupal exuviae from Hermetia illucens as a functional feed additive for laying hens: effects on performance, post-mortem traits, egg quality, nutrient digestibility and caecal short-chain fatty acid production

The present study evaluated the effects of purified chitin and ground pupal exuviae from Hermetia illucens as functional feed additives in laying hens. A total of 120 ISA Brown hens (25 weeks of age at the beginning of the trial; 28–39 weeks during the experimental period) were allocated to three dietary treatments for 11 weeks: a control diet (CTRL), a diet supplemented with purified chitin (CHIT; 7 g/kg, providing approximately 1 g/hen/day), and a diet supplemented with ground exuviae (EXU; 56 g/kg). Productive performance, egg quality, apparent ileal digestibility, abdominal fat deposition, organ traits, and caecal short-chain fatty acid (SCFA) concentrations were evaluated. The EXU group showed a lower feed conversion ratio compared with the control group, whereas feed intake and oviposition rate did not differ significantly among treatments. Both CHIT and EXU reduced crude protein digestibility compared with CTRL (P < 0.01), with no differences between chitin sources. Exuviae supplementation increased abdominal fat deposition (P < 0.05) and significantly enhanced total SCFA production. Egg quality traits were largely unaffected by dietary treatments. In conclusion, while purified chitin and exuviae exerted similar effects on protein digestibility, ground pupal exuviae induced a stronger fermentative response, likely reflecting the contribution of the whole exuviae matrix rather than chitin alone. These findings support the potential of H. illucens exuviae as a functional ingredient in laying hen nutrition.