Yellow mealworm as an alternative to conventional plant- and animal-based protein sources in feedlot lambs' diets: Implications on blood parameters, growth and slaughter performance, carcass traits, and meat quality.

This study evaluates the effects of Tenebrio molitor meal (TMM) as an alternative to conventional plant-based (soybean meal, SBM) and animal-based (fishmeal, FM) protein sources on blood parameters, growth and slaughter performance, carcass traits, and meat quality of feedlot lambs. A total of 24 Suffolk lambs [3 months of age, 21.4 ± 1.08 kg body weight (BW)] were allocated for 60 days to three treatments (8 lambs per treatment) in a completely randomized design, as follows: 1- SBM at 150 g/kg dry matter (DM)], 2- FM at 50 g/kg DM, and 3- TMM at 60 g/kg DM. Feed intake, BW, and blood samples were collected on days 0, 20, 40, and 60. At the end of the trial, the lambs were slaughtered for carcass evaluation and meat quality assessment. The average daily gain was higher for SBM-fed than for TMM-fed lambs (0.25 and 0.21 kg/d; P < 0.001). Plasma levels of creatinine were higher in FM-fed when compared to SBM-fed lambs, while TMM-fed lambs showed intermediate values (88.72, 85.69 and 87.57 μmol/L, respectively; P < 0.05). The hot and cold carcass weights (15.99 and 15.52 kg vs 18.49 and 18.03 kg) and yields (44.31 and 43.02 % vs 46.03 and 44.87 %) were lower in the TMM group compared with the SBM group (P < 0.05). The dietary treatment had no effect (P > 0.05) on meat pH, color, texture, water loss and contents of fat, protein, and moisture. Further research should evaluate optimal inclusion levels of TMM in combination with conventional protein sources to avoid negative economic implications.