Abstract:
The study was conducted to determine the factors those affect the tirst service pregnancy rate (PR). A total of
180 cows, local 80, LocalxHolstein·Friesian(LxHF) 55 and localxSahiwal (LxSL) 45 were selected tram
January, 2011 to December 2011 to identify the potential risk factors such as body weight, breed, age, body
condition score (BCS) and season to first service. Overall pregnancy rate at first Al (FAI) was 53.3% (n=96).
The highest pregnancy rate (56.3%) was observed in local cows, which was significantly (p<0.05) higher than
that of Holstein-Friesian x Local (47.3%) cows. Cows of 4-5 years of old revealed a significantly (p<0.05)
higher pregnancy rate than that of cows of 2·3 years age. The higher pregnancy rate (64.5%) was in cows of
BCS 3.5 than lower BCS 2.5 cows (31%; p<0.05). The pregnancy rate was higher in cows weighing between
151-250 kg (57.1 %) and lower in cows up to 150 kg body weight (35%, p<0.05). Cows showed significantly
(p<0.05) higher PR (59.6%) when FA! was done in winter (November-February) compared to spring (March-
April) calving cows (55.6%).
