Evaluating Dietary Red Lentil Screenings on Performance, Antioxidant Status, Caecal Environment, and Intestinal Morphometric Features in Rabbits

Among the goals of global environmental policies, one is to achieve a critical rethinking of the agro-industrial production chain aimed at enhancing its sustainability and resilience while addressing its environmental impact. Lentils are widespread worldwide and are consumed as part of traditional dishes, and their health-promoting benefits are currently well recognized. Their industrial processing for human consumption implies the generation of different by-products which can be used as promising alternative feedstuff. Calling for the future sustainable development of rabbit farming, the present study questions the dietary inclusion of red lentil screenings (RLS) as an upcycling strategy for this by-product, as well as to ease the challenges faced by the rabbit-farming system. A total of 120 male Bianca Italiana breed growing rabbits aged 42 days were allotted to three dietary treatments containing different levels of RLS: 0 (RLS0), 5 (RLS5), or 10% (RLS10), respectively, for 6 weeks. At 84 days (slaughter age), meat, plasma, and intestinal samples were collected. The RLS inclusion showed no adverse effects on growth performance. However, significant differences were found in the meat fatty acid profile, where both RLS5 and RLS10 groups showed reduced C18:0 percentage and higher MUFA content owing to an increase in C18:1 n-9; moreover, RLS5 showed a significant increase in C16:1 trans. On the other hand, only RLS10 recorded a significant reduction in the PUFA total content due to decreased single unsaturated fatty acid (C18:2 n-6; C20:3 n-6; C22:5 n-3). Dietary RLS significantly decreased serum total cholesterol, LDL, and HDL, along with an enhancement of the overall serum antioxidant capacity. The results regarding the rabbit caecal characteristics and microbial population were found to be similar among the groups. However, referring to histomorphometric measurements, both RLS5 and RLS10 groups displayed significant increases in villus height and an improved villus height to crypt depth ratio. In conclusion, up to 10% RLS in the diets rabbits can be considered an effort-effective feeding strategy to modulate rabbit meat fatty acid profiles, to enhance the endogenous antioxidant capacity, and to improve the serum lipid profile and intestinal morphology.