| Abstract |
Mealworms (Tenebrio molitor) have a great ability to bioconvert vegetable by-products used as feed into body mass. Rice straw is a vegetable by-product that is difficult to dispose of and causes environmental problems. The use of physicochemical or enzymatic treatments to improve the digestibility of these by-products can increase the performance of mealworms in terms of yield. In this study, mealworm larvae were reared on diets formulated with rice straw and rice straw subjected to a combined treatment of laccase enzyme, ultrasound, and ascorbic acid to evaluate the impact on the growth performance and digestibility of T. molitor. The combined sonication, laccase enzyme, and ascorbic acid treatment of rice by-products facilitated their use by T. molitor larvae, increasing the weight gain, feed conversion ratio, and conversion efficiency of ingested feed. The use of treatments capable of improving the usefulness of vegetable by-products opens the possibility of developing new methodologies for their use for insect feed. The development of reuse processes for plant by-products for both animal and human food offers numerous possibilities for quality-of-life improvements that align with a circular economy model. For this reason, we divided this study into two experiments. First, we designed a combined treatment consisting of laccase, ultrasound, and ascorbic acid to hydrolyze rice straw plant fibers and used the resulting feed as the basis for T. molitor diets. Second, we formulated diets with different inclusion levels (0%, 25%, 50%, 75%, and 100%) of rice straw and treated rice straw to assess their impact on larvae growth and diet digestibility. For each treatment, six replicates were employed: four for the growth-performance-digestibility trial and two for complementary uric acid determination tests. The combined laccase enzyme, ultrasound, and ascorbic acid treatment hydrolyzed 13.2% of the vegetable fibers. The diets containing treated rice straw resulted in higher larvae weight and a better feed conversion ratio; however, reaching 100% by-product inclusion values led to similar results between both diets. In conclusion, these treatments improve the potential of low-nutritional-value vegetable by-products as part of a T. molitor diet, opening the possibility of new methodologies for the use of recalcitrant vegetable by-products for insect rearing. |