Valorization of fermented orange pulp as a sustainable feed ingredient: Impacts on broiler growth, immune system, meat quality and lipid oxidation

The citrus industry produces vast quantities of by-products, such as orange pulp (OP), which can be valorized as alternative feed ingredients within sustainable poultry production systems. Fermentation is a promising biotechnological approach that enhances the nutritive and functional properties of agro-industrial by-products such as OP. In this study the effects of dietary inclusion of OP, either unfermented or fermented for 20 days, on broiler performance, carcass traits, meat quality, oxidative stability, immune parameters and serum lipid profiles were investigated. A total of 176 Cobb 500 broilers were assigned to four dietary treatments: control (basal diet), unfermented OP, OP inoculated with mixed inoculum without fermentation (T0), and OP inoculated with mixed inoculum and fermented for 20 days (T20), all at 7 % inclusion. Growth performance and most of carcass characteristics were not significantly affected by OP supplementation (P > 0.05). However, dietary OP influenced skin and meat coloration, with unfermented OP groups showing increased redness in comparison with either C or T20 groups. Fermentation significantly reduced malondialdehyde (MDA) levels in breast meat during storage, in comparison with groups fed with non-fermented OP (P < 0.05), thus showing improved oxidative stability. Serum total cholesterol was reduced in all OP-fed groups but at the same time high density lipoprotein (HDL) tended to increase (P < 0.1). A subtle immunosuppression was detected in broilers fed with unfermented OP in comparison with controls as shown from the reduced number of T cytotoxic cells determined in serum of OP and T0 groups (P < 0.05). These results support the inclusion of OP, particularly fermented, as a sustainable feedstuff that enhances meat quality and lipid profile without impairing broiler growth. Valorization of such an agro-industrial waste enhances circularity and promotes sustainable poultry feeding with respect to environmental protection.