Effect of photoperiod and other environmental factors on the oocyte populations of water buffalo (Bubalus bubalis) in Veracruz state, Mexico

The objective of this study was to investigate the effect of photoperiod and other environmental factors on the population of Water buffalo oocytes in Veracruz, Mexico. Oocytes (n=123) were obtained by follicular aspiration and graded according to morphological characteristics. Data regarding regional environmental factors (temperature, humidity, and daylight) were collected from a historic database of a metrological station. Statistical analysis was performed through Person correlation, one-way ANOVA and linear regression analysis, P<0.05 was considered significant. There was a correlation (P<0.05) between oocyte populations (total and viable) with temperature, humidity, and duration of daylight. ITH (index of temperature and humidity) and oocyte viability did not correlate (P>0.05) with other variables. Oocyte populations (total and viable) and environmental variables changed (P<0.05) during all the sampled months. Oocyte populations (total and viable) were affected (P<0.05) by temperature (r=-0.63; r=-0.57), humidity (r=0.46; r=0.39) and daylight (r=-0.86; r=-0.87), no association (P>0.05) with ITH or oocyte viability were identified. In conclusion, temperature, humidity, and daylight affected the oocyte populations (total and viable). Photoperiod seemed to be the most important factor affecting oocyte populations of water buffalos in Veracruz state, Mexico.