The actual performance records of first lactation 305 days or less milk yield (FL305MY) trait of Karan Fries cattle is a result of the interaction of both acting various genetic and non-genetic factors and thus, poor indicator their breeding values. The first lactation 305-day or less milk yield (FL305MY) records of 1481 Karan-Fries cows sired by 83 bulls calved during the period of 26 years from 1984 to 2009 remained after data editing were utilised in present study from the history-cum pedigree sheet and daily milk yield registers maintained at National Dairy Research Institute (NDRI), Karnal. The least squares mixed model fitting effect of genetic (sire) and non-genetic factors (periods, season and age groups) were used to analyze the data of FL305MY. The effect of sire (P≤0.01) and age at first calving groups (P≤0.05) was found to have significant effect on FL305MY. The season of calving and period of calving had non-significant effect on FL305MY. No definite trend of increase

Genetic, non-genetic, factors, first lactation 305 days or less milk yield, Karan Fries, cattle