The association between age and semen quality of Thai native roosters (Leung hang
khao) in relation to patterns of seminal plasma proteins were determined. Eighteen of the native
roosters were grouped according to the ages 7-8, 10-11 and 23-24 months. Semen was collected
by abdominal massage and evaluated for different physical parameters. Results showed that
semen volume, color, pH and sperm concentration were not significantly different among the
different age groups. In contrast, sperm viability was found to be significantly different. Sperm
viability was significantly higher in the 7-8 (93.34a ± 2.17) than the 23-24 months age category
(71.38b ± 7.44). Seminal plasma proteins were separated using sodium dodecyl sulphate
polyacrylamide gel electrophoresis (SDS-PAGE). Based on our findings, proteins with
molecular weight fractions of 72, 90, 140, 220, and 260 kDa showed patterns of expression in
7-8, 10-11, and 23-24 month old roosters, respectively. Moreover, proteins with molecular
weight fractions of 72, 90, and 140 kDa were shown sharply patterns of expression among age
of roosters. These results indicate that sperm vitality (percentage of live sperm or dead sperm)
and proteins with molecular weight fractions of 90, and 140 kDa are associated with age.
Proteins with molecular weight fractions of 90 and 140, kDa may serve as markers to determine
semen quality in Thai native roosters.