Influence of season on seminal plasma testosterone and oestrogen in healthy and abnormal buffalo bulls and their relationship with other semen parameters

Sixteen buffalo bulls (Bubalus bubalis) were divided into four age groups, four bulls in each. Bulls in three groups had good semen quality while in one group it was poor. The study was undertaken for a one-year period divided into five seasons. The study revealed an overall seminal plasma testosterone concentration of 0.97±0.12 ng/ml. It was higher (P<0.05) in the 6-10-year-olds, less than 5 and older than in 11-year-old bulls. Testosterone showed a non-significant difference between seasons. Overall seminal plasma oestrogen concentration was 43.67±7.62 pg/ml and showed a non-significant difference between healthy groups and between healthy and abnormal bulls. Oestrogen was higher (P<0.05) in winter than in other seasons in 6-10 and older than 11-year-old bulls, including abnormal bulls. Testosterone in healthy bulls showed significant positive correlation (P<0.05) with sperm concentration (r=0.223) and time between two ejaculates (r=0.242), while there was a significant (P<0.05) negative correlation with semen pH (r=-0.293). Oestrogen showed significant (P<0.01) positive correlation with semen pH (r=0.350) and negative (P<0.05) with time between two ejaculates (r=-0.296) and sperm head abnormalities (r=-0.262). Both hormones were negatively correlated (P<0.05) with each other (r=-0.277).