Zakirullah, Hamayun Khan, Ali Gohar, Haq Amanullah, Muhammad Younas, Muhammad Tarique Tunio, Muhammad Saleem Khan, Ibrar Muhammad Khan and Noushad Khan, 2019. L-Cysteine Addition in Tris-Citric Acid Extender Enhances Functional Characteristics of Post-Thaw Spermatozoa in Achai and Holstein Friesian Bulls under Subtropical Environment. Pakistan J. Zool., 51: 2193-2198. DOI: http://dx.doi.org/10.17582/journal.pjz/2019.51.6.2193.2198