Dietary utilization of mealworm frass in rabbit feeding regimes and its effect on growth, carcass characteristics, and meat quality

Abstract

This study aimed to shed light on the use of mealworm (Tenebrio molitor) frass (TMF) in rabbit diets and its effects on growth performance, blood profiles, rabbit meat quality, and fatty acid profiles. A total of 48 Gabali rabbits were divided equally and randomly into four groups to be fed one of four dietary treatments: a control (T0) group and three TMF groups, which included TMF meal at 1 (T1), 2 (T2), and 3 (T3) %, respectively. The rabbits were fed on isonitrogenous and isoenergetic diets for 11 weeks, and the growth performance data were recorded. Six rabbits per group were slaughtered at the end of the 11th week, then the pharmacochemical parameters and carcass traits were measured, and meat quality and fatty acid profiles were analyzed. The results indicated that the growth performance of different groups was similar (P > 0.05). The levels of globulin, glucose, and alanine transaminase (ALT) were lower in the mealworm frass groups compared with the control group. Carcass traits were not affected by experimental regimes. Fat was higher in the TMF treatment groups, while moisture was lower compared with the control group. The shear force had a lower value in the treatment groups T3 and T2 compared with the control group. The highest values of redness and chroma (color parameter) of rabbit meat were observed in the treatment groups vs. the control group. Moreover, the proportion of total saturated fatty acids in the meat of rabbits that were fed on the T2 and T3 diets was higher compared to those fed on the control (i.e., T0) and T1 diets. Furthermore, the proportion of monounsaturated fatty acid was higher in the T2, T3, and T1 groups vs. T0 rabbits, whereas the PUFA proportions were lower. It could be concluded that frass has great potential to be used as a partial substitute for rabbit diets.

Opportunities and challenges in upcycling agri-food byproducts to generate insect manure (frass): A literature review

“…Currently, agriculture, horticulture and retail appear as the primary markets for frass applications as a fertilizer (Chavez and Uchanski 2021) , Larouche 2022. However, applications of frass as a potential ingredient in animal feed (fish , Banavar, Amirkolaei et al 2022), shrimp (Yildirim-Aksoy, Eljack et al 2022, rabbits (Radwan, Maggiolino et al 2023)), and/or secondary processing (feedstock for biomethanisation (Wedwitschka, Gallegos Ibanez and Jáquez 2023), for composting (Song, Ee et al 2021), or for biochar production (Yang, Chen et al 2019, Yang, Zhang et al 2019)) are emerging. Considering the strong growth of the edible insect sector, and the high ratio of frass production per tonne of edible insects harvested, it is therefore important to find value-added opportunities to consolidate the economic model of current and future insect productions.…”