Obi, C.N., et al. “Evaluation of Feeding Different Digestible Lysine Intake Levels on Semen Characteristics and Body Weight of Broiler Breeders During Pre-Peak and Peak Production”. International Journal of Poultry Science, vol. 12, no. 2, Jan. 2013, pp. 64–71, https://doi.org/10.3923/ijps.2013.64.71.