Waksman I., Nir O., Galon N.
Hachaklait Veterinary Services Ltd, Israel

The objectives of the study were to evaluate the reproductive benefits of early pregnancy diagnosis (PD) using transrectal ultrasonography (US) and to asses the rate of early embryo/fetal death (EED) and loss in commercial dairy herds in Israel. Currently all pregnancy diagnosis are performed by transrectal palpation (RP) at 40-50 days post insemination. The drive to increase farm efficiency and profit has led Hachaklait to test the benefit of using US in reducing days open. Materials and methods: Two intensive Israeli Holstein Herds (A with 900 and B with 650 milking cows) producing >11,000 kg of milk/cow/year, and use automatic pedometry systems (recording cow steps) for heat detection. A controlled randomized trial was conducted from July 2006 until December 2007. Anoestrus cows were treated according to each farm protocols. Total of 1450 cows of all lactations after artificial insemination (AI) were randomly allocated into tow nearly equal groups: US and RP. The RP cows were submitted to PD by fetal membrane slip technique between days 42-48 after AI, and the US cows were PD between days 26-32 after AI and reexamined by RP between days 42-48 after AI. Cows which were detected on heat between AI and the set PD time in each group were reinseminated. Results: Days open were 122 and 123 in the small farm, and 115 and 115 in the large farm, in the US and in the RP groups respectively, with no statistically significant differences. The groups did not differ significantly in following reproductive risk factors: endometritis, ketosis, negative energy balance and summer calving. Most of the active open cows were detected on heat and reinseminated before reaching the first PD. The EED rate in the US group, measured by the drop of pregnancy rate between the day 26-32 and the day 42-48 PD, was 5.9% and 6.1% in farm A and B respectively. Conclusion: There was no difference in days open and therefore no reproductive benefit in early ultrasound pregnancy diagnosis in these tows herds. As part of the open cows were detected on heat before the US PD and the true anestrous cows take longer to conceive, the potential 14 days advantage in days open for the US cows was reduced to an insignificant difference.