High Fiber Cakes from Mediterranean Multipurpose Oilseeds as Protein Sources for Ruminants

SIMPLE SUMMARY: Recovery and valorization of residues are key factors for agro-industry to progress towards circular-economy models and more sustainable productions. In the vegetable oils industry, large quantities of spent seed cakes are produced downstream of the oil extraction processes, and their use as animal feedstuffs, mainly as protein supplements for ruminants, is a possible valorization strategy. In this study, we analyzed chemical composition and in vitro digestibility of spent cakes from sunflower, pomegranate, cardoon, tobacco and hemp that are multipurpose cultures emerging in Mediterranean area. The results showed that the cakes of tobacco, cardoon and hemp might be interesting alternative protein feeds for ruminants. The valorization of these cakes may potentially improve economic and environmental sustainability of the emerging vegetable-oil production chains. ABSTRACT: Fifteen oilseed cakes from sunflower, pomegranate, cardoon, tobacco and hemp were characterized with regard to chemical composition, Cornell Net Carbohydrate and Protein System (CNCPS) fractionation, in vitro digestibility of dry matter, neutral detergent fiber, and crude protein. All the cakes presented low moisture, rather variable ether extract contents and medium to high levels of crude protein and neutral detergent fiber. The cakes significantly differed in terms of CNCPS partitioning and in vitro digestibility. Tobacco and hemp cakes presented high contents of slow degradable fractions of crude protein and carbohydrate joined to good post-ruminal protein digestibility. Cardoon cakes presented the highest rumen protein degradability. Based on crude protein content and intestinal digestibility of rumen undegraded protein, cakes of tobacco and hemp showed the better potential as alternative protein supplements for ruminants, while pomegranate appears to be the least suitable for ruminant feeding.