Reproductive performance of friesian cows in Saudi Arabia I. calving interval, gestation length and days open

This study involves analyses of 590 records of Imported and Saudi-born Friesian cows belong-ing to two farms located at Riyadh region. The overall means for calving interval, gestation length and days open were 414.5 :t 5.8, 276.4 :t 0.8 and 138.0 :t 5.8 days for imported cows. The corresponding values for local-born cows were 399.8 :t 8.6, 276.9 :t 1.1 and 122.9:t 8.5 days. The variations in calving interval primarily were dut to those in days open. The effects of farm and season of calving on the later two traits were non-significant. First-parity cows had longer days open and longer calving intervals than older cows. This effect of parity was significant only on imported cows. The relationships between parity with calving interval and days open were negative andsignificant (r = -D.16 and -0.11, respectively). Cows calving during the summer had shorter gestations than those calving during the winter. This study suggests that good heat detection, proper inseminations and adequate feeding should reduce both calving interval and days open for Friesian cows in Saudi Arabia