Diet supplemented with olive cake as a model of circular economy: Metabolic and endocrine responses of beef cattle

Introduction Integrating by-products into livestock diet represents a great opportunity for implementing the concept of circular economy while reducing feed costs. Olive cake (OC) is considered an agro-industrial waste, but high content valuable metabolites makes it promising integration. Therefore, this study investigated effect OC integration in beef cattle on different blood parameters. Methods Forty-eight young growing fattening Limousines-?24 bulls (body weight 350 ± 15 kg) and 24 heifers (280 10 kg)—, aged 240 20 days, were randomly allocated to 1 3 dietary treatments: concentrate at 0% (Control group: CTR), 10% (Low-olive L-OC), or 15% (High-olive H-OC) inclusion. Blood samples body weights collected before administrating supplemented (0 d), end stocker phase (56 (147 d). After being slaughtered, animal carcasses weighted. A linear regression model was fitted each parameter with 0 d as covariate diet, time, sex, × sex fixed effects. Results In males, highest CTR, carcass similar all groups. All parameters within physiological ranges, independently from diet. CTR group showed alanine aminotransferase (ALT, P = 0.0027) creatine kinase ( 0.0119), whereas total bilirubin 0.0023) higher H-OC than CTR. Moreover, ALT 56 d, becoming groups 147 0.0280). Instead, increase observed cholesterol lower compared L-OC 0.0451). significant interaction triglycerides, urea, liver enzymes, insulin. These data support inclusion up no detrimental metabolic status. Discussion conclusion, can be component giving improve agriculture sustainability.