Effect of pregnancy on body weight and pelvic conformation in crossbred cows (Friesian x Gir and Jersey x Gir).

Studies were conducted into 80 pregnant crossbred cows belonging in equal numbers to 1/2Friesian (F) 1/2Gir (G) and 1/2Jersey (J) 1/2G genetic groups to determine the effect of pregnancy on body weight (B.W.) and pelvic conformation of the dam. Mean B.W. started to increase in 1/2F1/2G/1/2J1/2G genetic groups from 406.08 +/- 6.16/375.45 +/- 7.73 kg on the 120th day of pregnancy and reached its maximum of 470.42 +/- 7.22/428.05 +/- 8.36 kg on the day of calving. A significant increase in weight occured in both groups between the 240th and 270th days of pregnancy. Total weight gain in both groups during pregnancy was 63.34/52.60 kg. There was a steep fall (P less than 0.01) in B.W. in both groups, within 1 month after calving. Weight became stable 60 days after calving in both groups. The cows in the 1/2F1/2G group were significantly heavier (P less than 0.01) than the 1/2J1/2G group, all the time. The mean pelvic outlet area started to increase in 1/2F1/2G/1/2J1/2G groups from 278.28 +/- 4.03/249.29 +/- 5.02 cm2 by the 120th day of pregnancy. Like B.W., the pelvic area, too, increased significantly (P less than 0.01) between the 240th and 270th days of pregnancy and dropped within 1 month post partum in both groups. Total increase in pelvic area was 49.15/39.76 cm2 in both groups, between the 120th day of pregnancy and calving. The area became stable 60 days after calving in both groups. The pelvic area in the 1/2F1/2G group was always significantly larger (P less than 0.01) than that in the 1/2J1/2G group.(ABSTRACT TRUNCATED AT 250 WORDS)