49 The aim of the present study was to evaluate the animal 50 performance, haematochemical parameters, intestinal 51 morphology and histological features of broiler chickens fed 52 diets including Tenebrio molitor (TM) larvae meal. A total of 53 160 female broiler chicks (Ross 708) at one-day of age were 54 randomly allotted to four dietary treatments: a control (C) 55 group and three TM groups, in which TM meal was included at 56 50, 100 and 150 g/kg, respectively. Each group consisted of 57 five pens as replicates, with eight chicks per pen. After the 58 evaluation of growth performance and haematochemical 59 parameters, two birds per pen were slaughtered at 40 days and 60 carcass traits were recorded. Morphometric investigations were 61 performed on duodenum, jejunum and ileum and 62 histopathological alterations were assessed for liver, spleen, 63 thymus, bursa of Fabricius, kidney and heart. The live weight 64 (LW) showed a linear (12 days, P < 0.05, maximum with 65 TM15) and quadratic response (40 days, P < 0.05, maximum 66 with TM5) to dietary TM meal inclusion. The average daily 67 gain (ADG) showed a linear increase (1-12 days, P < 0.05, 68 maximum with TM15) in response to TM meal utilization. A 69 linear effect (1-12 and 12-25 days, P < 0.01 and P < 0.05, 70 maximum with TM15 and TM5) was observed for the daily 71 feed intake (DFI). The feed conversion ratio (FCR) showed a 72 linear response to TM utilization in the period 12-25 days (P < 73 4 0.01, maximum with TM15). A quadratic effect (P < 0.05, 74 maximum with TM5) was observed for the carcass weight. The 75 abdominal fat weight and percentage showed a linear response 76 to dietary TM meal inclusion (P < 0.05 and P < 0.01, maximum 77 with TM15 and TM10). A quadratic increase (P < 0.05, 78 maximum with TM10) was observed for the erythrocytes, 79 while the albumin and GGT showed a linear and quadratic 80 decrease (P < 0.05, minimum with TM10) in relation to TM 81 utilization. Gut morphology and histopathological findings 82 were not significantly influenced (P > 0.05) by dietary TM 83 meal inclusion. The present study suggests that increasing 84 levels of dietary TM meal inclusion in female broiler chickens 85 diets may improve body weight and feed intake, but can 86 partially worsen feed efficiency. However, positive effects on 87 carcass traits and haematochemical parameters related to TM 88 meal utilization are observed, along with no negative influence 89 on gut morphology and histological findings. 90 91 Keywords 92 Poultry; Tenebrio molitor; insect meal; growth performance; 93 histology; morphometry. 94 95 96 World population is expected to increase by over a third, 97 reaching over 9 billion people in 2050. This trend suggests that 98 market demand for food will continue to grow. In particular, 99 the demand for cereals and protein sources in both human food 100 and animal feed is projected to have an exponential growth by 101 2050 (FAO, 2013). Consequently, the world supply of some 102 conventional feedstuffs like soybean and maize will 103 ...