Simple SummaryThere is a predicted increase in the world population by 2050, and the main task will be to ensure sufficient safe food. In the situation of food–feed–biofuel competition, a circular economy can represent a smart solution. The utilization of agricultural/food wastes and byproducts by insects to gain quality feed components, such as insect meals, for monogastric animals seems to be one suitable solution. In this study, we evaluated the effect of diets based on insect meal (adultAcheta domesticus, AD, andTenebrio molitorlarvae, TM) in comparison with soybean meal (SM) on the coefficient of the total tract apparent digestibility of the experimental diets, the nitrogen balance, and the growth performance of rabbits. Based on the results of this study, it can be concluded that both insect meals tested (AD and TM) are suitable dietary crude protein sources that can fully replace SM (currently criticized because of deforestation) for growing-fattening rabbits. Regarding nitrogen output, it seems that the dietary inclusion of AD in rabbit diets might have better potential in terms of an environmental impact than the dietary inclusion of TM because of the higher essential amino acid content in AD.AbstractThree diets were formulated, i.e., soybean meal (SM diet), adultAcheta domesticus(AD diet), andTenebrio molitorlarvae (TM diet), as the main crude protein (CP) sources. A total of 45 rabbits (Hyplus, weaned at 32 days of age) were divided into three groups (15 per treatment) and fed one of the three diets for 42 days. A higher daily weight gain (p= 0.042), as well as daily feed intake (p= 0.022), was observed in rabbits fed the AD and TM diets than in rabbits fed the SM diet within 21 days after weaning. The coefficients of total tract apparent digestibility (CTTAD) of gross energy were higher (p= 0.001) in rabbits fed the SM diet than in rabbits fed the other diets. The CTTAD of CP (p= 0.040) and starch (p= 0.041) was higher in rabbits fed the SM diet compared to those fed the AD diet. There were non-significantly higher losses of nitrogen in the urine (an average by 0.227 g/day;p= 0.094) in rabbits fed the TM diet than in rabbits fed the other diets. It can be concluded that the growth of rabbits and nitrogen output were not detrimentally affected by the insect meal (AD or TM) used in this study.