Effect of three production systems of central Mexico on growth performance of five lamb genotypes - J. R. Galaviz-Rodríguez; J. E. Ramírez-Bribiesca; S. Vargas-López; J. L. Zaragoza-Ramírez; J. D. Guerrero-Rodríguez; M. Mellado-Bosque; R. G. Ramírez (Journal of Animal and Plant Sciences, 2014)