Panithi SukhoHiran JuwarahawongSlitwan SangiamKampon KaeoketMahidol University. Faculty of Veterinary Science. Dapartment of Clinical Sciences and Public Health Department2018-06-062018-06-062018-062013Journal of Applied Animal Science. Vol.6, No.1 (2013), 43-521906-2257https://repository.li.mahidol.ac.th/handle/20.500.14594/13328The aim of this study was to investigate the effect of supplementation of L-Cysteine in Modified Kenny's extender on chilled stallion semen quality at 5oC. Semen samples were collected from 3 stallions by artificial vagina and centrifugation to remove seminal plasma and diluted with Modified Kenny's extender to 50 x 106 sperm/ml. Semen samples (n=10 ejaculates) were divided into 3 portions, the first portion as the control (KE), the second portion was added with L-Cysteine 200 μmol/l (KEC200) and added L-Cysteine 400 μmol/l in the last portion (KEC400). In all samples, the percentage of progressive motility, viability and acrosome integrity were evaluated at 0, 24, 48 and 72 h after storage at 5oC. There were a significant (P < 0.05) lower percentage of dead spermatozoa in group KE200 than other groups at 24 h. There was a significantly lower percentage of progressive motility in KEC 400 compared toother groups at 48 h (P < 0.05). In addition, there was a tendency (P = 0.1) of lower percentage of dead spermatozoa in group KE200 than other groups at 48 h. At 72 h, comparing all groups, a higher percentage of viability in groups KEC200 and KEC400 was found, but not statistically significant. In conclusion, Addition of L-cysteine at a concentration of 200 μmol/l to the Modified Kenney's extender tend to improve the stallion chilled semen progressive motility, dead/alive, viability and acrosome integrity during chilled storage at 5oC for 48 h.engMahidol UniversityStallionSpermChilled semenL-CysteineAntioxidantJournal of Applied Animal ScienceResearch ArticleFaculty of Veterinary Science Mahidol University