Effect of genetic and non-genetic factors on first lactation 305 days milk yield in Gir halfbreds

The productive performance data of Gir halfbreds maintained at the Research cum Development Project on Cattle (RCDP), Mahatma Phule Krishi Vidyapeeth, Rahuri district, Ahilyanagar, Maharashtra, were utilized for the present study. First lactation 305-day milk yield least squares means were analyzed considering both sire (genetic factor) and non-genetic factors such as period, season, and age at first calving. The least squares mean observed for FL305DMY in Gir halfbreds was 1965.64±61.51 kg. The period of calving had a significant effect on first lactation 305-day milk yield (FL305DMY) (P<0.01) indicating that the year when a Gir halfbreds gives birth has an important impact on the amount of milk she produces during her first lactation, measured over 305 days. Age at first calving had a significant effect on first lactation 305-day milk yield (FL305DMY) (P<0.01) indicating that the age at which a cow first gives birth has a statistically significant impact on the amount of milk she produces during her first lactation period, measured over a standard 305-day period while The season of calving did not have a significant effect on FL305DMY indicating that the season in which a cow gives birth for the first time does not have an impact on the total milk she produces during her first lactation, measured over 305 days. The genetic factor, sire, did not have a significant effect on the trait indicating that the genetic influence of the sire does not have a statistically meaningful impact on the milk yield produced by his daughters during their first lactation 305-day period based on the data analyzed.