Data of one hundred animals of two filial groups ½ (Fl and F5) had been analysed in this study. The animals were maintained at Livestock Production Research Institute, Bahadarnagar, Okara during the year 1981-1999. The data was analysed to estimate the magnitude of different reproductive traits, namely, the age at maturity/puberty, age at first conception, age at first calving, service period, calving interval, gestation period, dry period, number of services per conception and conception rate.

The average mean values for the filial groups 34 (Fl and ES) of Holstein Friesian x Sahiwal crossbred cows i.e., Age at maturity, Age at first conception and Age at first calving were 725.98 days or 84 months and 740.95 days or 24 months, 761.54±216.67 days or 25 months and 789.73±138.64 days or 26 months and 1040,7±218.47 days or 34 months and 1069.60± 139.92 days or 36 months respectively. The average mean values for Service period and No. of service per conception were 178.90±114.04 days and 222.93±163.67 days and 2.15± 1.10 and 2.20± 1.15 respectively. For gestation period and Calving interval the average mean values were 279.19±8.0 days or 9 months and 280.53±7.8 days or 9 months and 459.54±115.54 days, 522.04±162.46 days respectively for the filial groups ½ (Fl and F5) of the Holstein Friesian x Sahiwal crossbred cows. The average mean values for the Dry period and Conception rate in the present studywere 155.79±104.54 days, 215.40±139.26 days and 2.15±1.10% and 2.20±1.15% for the ½ (Fl and F5) respectively.

The present study indicates that there is non-significant difference among the following reproductive traits of filial groups ½ (Fl and F5) i.e., Age at maturity/puberty, Age at 1st conception, Age at 1st calving, Gestation period, No. of services per conception and conception rate.

This study describes that there is a significant difference among these reproductive traits of ½ (Fl and F5) filial groups of Holstein Friesian x Sahiwal crossbred cows i.e., Calving interval, Service period and Dry period.

The main object of the crossbreeding was to evolve a new breed of cattle and even upto fifth generation the results are encouraging.

By the encourgining results of this study it is recommended/suggested that at present about 2 million heads of non-descript cattle population having very low genetic potential may be come useful by inseminating with exotic semen of Holstein Friesian. The crossbred animals have much superior germplasm as compared to non-discript animals.

Further, it is recommended to maintain fifty percent exotic blood level, which is best suited in the subtropical environmental countries like Pakistan.