Ruiz, Teodoro M., and Efraín Cancel-Medina. “Performance of Holstein Cows Fed Two Levels of Concentrate Supplementation and Ruminally Undegraded Protein.”. The Journal of Agriculture of the University of Puerto Rico 90, no. 1-2 (January 1, 2006): 9-26. Accessed January 27, 2022. https://revistas.upr.edu/index.php/jaupr/article/view/2958.