Effects of yellow mealworm larvae (Tenebrio molitor) inclusion in diets for female broiler chickens: implications for animal health and gut histology

The aim of the present study was to evaluate the animal performance, haematochemical parameters, intestinal morphology and histological features of broiler chickens fed diets including Tenebrio molitor (TM) larvae meal. A total of 160 female broiler chicks (Ross 708) at one-day of age were randomly allotted to four dietary treatments: a control (C) group and three TM groups, in which TM meal was included at 50 (TM50), 100 (TM100) and 150 (TM150) g/kg, respectively. Each group consisted of five pens as replicates, with eight chicks per pen. After the evaluation of growth performance and haematochemical parameters, two birds per pen were slaughtered at 40 days and carcass traits were recorded. Morphometric investigations were performed on duodenum, jejunum and ileum and histopathological alterations were assessed for liver, spleen, thymus, bursa of Fabricius, kidney and heart. The live weight (LW) showed a linear (12 days, P < 0.05, maximum with TM150) and quadratic response (40 days, P < 0.05, maximum with TM50) to dietary TM meal inclusion. The average daily gain (ADG) showed a linear increase (112 days, P < 0.05, maximum with TM150) in response to TM meal utilization. A linear effect (1-12 and 12-25 days, P < 0.01 and P < 0.05, maximum with TM150 and TM50) was observed for the daily feed intake (DFI). The feed conversion ratio (FCR) showed a linear response to TM utilization in the period 12-25 days (P < 0.01, maximum with TM150). A quadratic effect (P < 0.05, maximum with TM50) was observed for the Carcass weight. The abdominal fat weight and percentage showed a linear response to dietary TM meal inclusion (P < 0.05 and P < 0.01, maximum with TM150 and TM100). A quadratic increase (P < 0.05, maximum with TM100) was observed for the erythrocytes, while the albumin and GGT showed a linear and quadratic decrease (P < 0.05, minimum with TM100) in relation to TM utilization. Gut morphology and histopathological findings were not significantly influenced (P > 0.05) by dietary TM meal inclusion. The present study suggests that increasing levels of dietary TM meal inclusion in female broiler chickens diets may improve body weight and feed intake, but can partially worsen feed efficiency. However, positive effects on carcass traits and haematochemical parameters related to TM meal utilization are observed, along with no negative influence on gut morphology and histological findings.