Live Tenebrio molitor larvae as a dietary supplement for post-weaning piglets: effects on performance and health under diets with different crude protein levels

Introduction: Weaning represents one of the most critical phases in pig production, as it is often characterised by a transient period of fasting that can impair gut integrity and ultimately reduce growth performance while increasing susceptibility to disease. At the same time, increasing pressure to reduce dietary crude protein and reliance on conventional protein sources has highlighted the need for feeding strategies that support the sustainability of feed formulations and animal health. Aim: This study evaluated the effects of daily supplementation with live Tenebrio molitor larvae on performance, feed intake, health status, digestibility and metabolic markers in post-weaning piglets fed diets containing moderate (15%) or standard (17%) crude protein levels. Methods: A total of 48 piglets were allocated to four treatments: control diets without larvae (CTRL15 and CTRL17) and corresponding diets supplemented daily with 50 g/pig/day of live mealworm larvae (INS15 and INS17). Growth performance, feed intake, feed efficiency, time required to consume the larvae, health indicators, apparent total tract digestibility, serum biochemical parameters, antioxidant capacity and mineral profile were assessed over a 42-day trial. Results and discussion: Larvae supplementation significantly improved early feed efficiency and growth performance (p < 0.05), particularly during the first weeks post-weaning. Piglets in INS17 achieved higher final body weight compared with CTRL groups (p < 0.05), while INS15 piglets reached performance comparable to CTRL17, despite the lower dietary protein level. Live larvae were rapidly and consistently consumed from the moment of supplementation, with consumption time decreasing below 2 min during days 30–42 of the trial, whereas soybean meal supplementation elicited lower feeding interest in piglets with longer consumption time. Larvae supplementation was associated with an improved health status, including a lower incidence of diarrhoea, reduced occurrence of respiratory disorders and higher vitality scores compared with control groups (p < 0.05) throughout the trial. No differences were observed in nutrient digestibility, serum metabolic profile and antioxidant status at day 42. Conclusion: In conclusion, live T. molitor larvae represent a promising functional feeding strategy to stimulate early feed intake during weaning and enhance piglet resilience, supporting growth performance and health while allowing dietary protein levels to be moderately reduced without negative effects.