A. Afzalzadeh, H. Rafiee, A. Khadem, and A. Asadi, “Effects of ratios of non-fibre carbohydrates to rumen degradable protein in diets of Holstein cows: 1. Feed intake, digestibility and milk production”, SA J. An. Sci., vol. 40, no. 3, pp. 204–212, Nov. 2010.