Estimates of genetic trends of some economic traits in Sahiwal herds

The records on 2185 Sahiwal cows maintained at 5 locations, viz. Kamal (605 cows), Durg (240 cows), Hisar (368 cows), Meerut (357 cows) and Lucknow (615 cows) were used in this investigation. A significant decrease in age at first calving at genetic scale was recorded in majority of the herds as estimated by various methods, which indicated considerable genetic improvement in the trails. A genetic trend of increase in milk yield per day of lactation length was observed for Karnal and Meerut herds by all the three methods, whereas genetic decrease in this trait was observed by all methods for Durg. Significant annual genetic decrease in first calving interval was obtained by method III for Kamal (7.20+/-3.24 days), Meerut (18.66+/-6.85 days) and Lucknow (11.08+/-2.89 days) herds. The estimates obtained by methods I and II were negative and nonsignificant statistically far all the 5 herds except for Hisar (0.66+/-6.50 days) by method II.