Abstract

    The present study was conducted to investigate the reproductive performance of 179 Red Sindhi cows with 485 lactation records covering 19 years period from 1978 to 1997, kept at the Government Red Sindhi Cattle Farm, Hub Chowki, District Lasbela (Balochistan). The effects of different known factors like year of birth/calving, season of birth/calving and cow were studied. The least squares mean (LSM) for age at first service (AFS), age at first conception (AFCO) and age at first calving (AFC) were 1024.86+27.54, 1043.02+31.46 and 1346.55+27.34 days, respectively, whereas the service period (SP), gestation period (GP), calving interval (CI) and number of services per conception (SPC) were 235.87+14.05 days, 283.15+0.64 days, 515.28+13:84 days and 1.63+0.07, respectively. Year of birth/calving significantly affected (P<0.01) all the traits studied, whereas the season of birth/calving significantly (P<0.01) affected the service period and calving interval. Service period, gestation period and calving interval differed significantly between cows. The effect of lactation number on gestation period and services per conception was investigated, which significantly (P<0.01) affected the services per conception but not the gestation period. The variation in the effects of different factors on the traits may be due to different environmental conditions, managemental practices, feeding planes, housing systems and personal skill of labour engaged in farm operations.