Abstract   

The data on 1491 breeding records of service period and calving interval of different grades of H. Friesian x Sahiwal 75, 62.5, 37.5, 25% and ½ (Fl, F2, F3, F4) crossbred over a period of 19 years (1976-1994) were utilized. T overall average least square means and SE for service period and calving interval were 137,4 ± 6.82 and 419.78 ± 6.04 days, respectively. Both traits were significantly (P>0.0l) influenced by year, season and parity of calving, while the year x season interaction had non-significant effect on both traits. The Spring season calvers and older cows were having shorter service period and calving interval.