J. anim. sci. J. anim. sci. The gut microbiota as a predictor of feed efficiency and feeding behavior in Iberian pigs Nuñez Pedro Casto-Rebollo Cristina Martinez-Boggio Guillermo Negro Rama Sara Casellas Joaquim Varona Luis Universidad de Zaragoza Pena Romi Peñagaricano Francisco Ibáñez-Escriche Noelia 2025 research-article