Application of poisson generalized linear model for analyzing effects of temperature and relative humidity on the number of insemination per conception of Holstein cows

To analyze the effect of some environmental factors on the number of insemination per conception، 9125 insemination records obtained from first lactation Holstein cows which were inseminated during 1989-2008 were utilized. All records were collected from a very large dairy herd which comprised of two units. Poisson model was applied as the statistical model. In the model، effects of year and month of insemination، technicians and units were fitted as fixed. Also temperature and relative humidity in the day of insemination were fitted as covariates. The statistical model was run using GLIMMIX procedure of SAS software. The results showed the effects of year of insemination، unit and temperature on the number of insemination per conception were significant، but month of insemination، technicians and relative humidity didn’t have statistically significant effect on the number of insemination per conception.