Impact of Opuntia spp. by-product silage on sheep metabolic profile, rumen fermentation and microbial communities

BACKGROUND: Prickly pear (Opuntia ficus-indica) by-products represent a promising alternative feed resource for improving the sustainability of sheep production systems in Mediterranean areas. This study evaluated the effects of prickly pear by-product (PPB) silages on rumen fermentation, metabolic profile, and rumen microbiome in lactating ewes. Twelve Valle del Belice ewes were assigned to three dietary treatments (control, CTR; prickly pear peel silage, PPP; and pastazzo silage, PPS) in a Latin square design. Blood biochemical parameters, rumen volatile fatty acids (VFA), and metagenomic profiles were analysed. RESULTS: PPB inclusion did not induce significant changes in blood biochemical parameters, which remained within physiological ranges. Rumen fermentation parameters were significantly affected, with the PPP diet increasing total VFA concentration and promoting a more glucogenic profile through higher propionate production. The rumen microbiome was dominated by Prevotella, which showed higher relative abundance in the CTR diet. PPB supplementation was associated with shifts in microbial functional profiles, including pathways related to polyphenol degradation, vitamin K2 biosynthesis, and central carbon metabolism, partially consistent with observed changes in rumen fermentation. No significant effects were observed on methanogenesis-related pathways. CONCLUSIONS: Prickly pear by-product silages, particularly prickly pear peel, modulate rumen fermentation and microbial functional profiles in lactating ewes without adversely affecting systemic metabolic status.