Data on 1200 Murrah buffaloes spread over 36 years collected from National Dairy Research Institute (NDRI), Karnal were utilized for the present study. Time series analysis of data was done to ascertain exact periods for various first lactation traits. The exact periods formulated were 7 years for AFC, 5 years for FL305DMY, and 6 years for FLTMY, 5 years for FLL, 7 years for FSP, 7 years for FDP and 7 years for FCI. The least squares means estimated for these traits with above periods were 1352.65 ± 6.19 days, 1812.58 ± 19.11 kg, 1948.60 ± 24.51 kg, 321.62 ± 2.34 days, 142.84 ± 4.05 days, 134.85 ± 2.87 days and 453.01 ± 4.08 days respectively. The least squares analysis of variance showed significant effect (P & 0.05) of month of birth on AFC and highly significant effect (P & 0.01) of month of calving on FDP, FSP and FCI only, while highly significant effect (P & 0.01) of period of birth on AFC and period of calving on all other first lactation traits except FDP was observed.
Time series analysis, Genetic factors, Non-genetic factors, Least square means
