RESUMEN
To study the seasonal variation in the characteristics of the Azarbaijani buffalo semen, three 2-4-year-old bulls of Azarbaijani water buffaloes, kept in the Buffalo Breeding Center, in Urmia, northwest of Iran, were selected. Semen samples were collected once a week for a period of one year using artificial vagina and a buffalo cow as a dummy. Semen volume, colour, pH and motility and spermatozoa motility, viability, morphology and concentration were examined. During one calendar year, 129 semen samples were examined. The mean values were plotted and a curve was drawn for the annual variations in each parameter. The comparison of the mean values in each sampling and in different seasons and the correlation between these variations and ecological factors, such as temperature, rainfall and day length were also studied. Semen was characterized by a mean [ +/- SEM] ejaculation volume of 4 +/- 0.14 ml, semen colour density score of 3.75 +/- 0.07, pH of 6.97 +/- 0.03 and motility score of 2.89 +/- 0.05. The sperm motility of 75.85% +/- 1.59% and sperm viability of 73.2% +/- / 1.56% were observed; 11.55% +/- 0.42% of spermatozoa had abnoraml morphology. The mean [ +/- SEM] sperm concentration was 1239.9 +/- 34.11 x 10 [6] cells/ml. All of the studied parameters showed fluctuations throughout the year but these variations were statistically significant only in some occasions and were mostly correlated with length of the day. Semen of better quality was collected in summer and autumn