USE OF REAL-TIME ULTRASONIC-SCANNING FOR THE DETECTION OF REPRODUCTIVE FAILURE IN PIG HERDS

Reproductive failure in a pig farm in which farrowing rate was lower than 70% was investigated ultrasonographically. A total of 190 sows of different breeds and parities were examined. Both pregnancy diagnosis and exploration of the left and right ventral abdominal wall were performed using a portable ultrasonograph with electronic linear transducer of 3.5 MHz. Sows were scanned in the standing position in individual gestation crates 21-22, 23-25, 26-28, 32-37 and 46-49 days after the second insemination. The sensitivity of the test was 95.2% 21-22 days after insemination and reached 100% from 23-25 days onwards. The specificity of the test, however, was lower (about 70-80% 21-49 days after insemination). Of 190 sows inseminated, 145 farrowed, and one had an observed abortion. Forty-four (23.15%) returned to oestrus or failed to farrow and of these, 21 (47.72%) presented no abnormalities in the uterus and returned to oestrus 18-25 (11 sows), 25-35 (two sows), 36-45 (seven sows) or > 45 (one sow) days post-insemination. Four sows (9.1%) were diagnosed empty between 21 and 49 days post-insemination and no returns to oestrus were observed. Five sows (11.35%) with delayed returns were previously diagnosed not pregnant but with endometritis. In four sows (9.1%) the false-positive diagnoses might have been caused by total embryonic mortality, as embryonic vesicles were detected between Days 22 and 28. In ten sows (22.73%) unobserved abortion was the probable reason for their failure to farrow because both conceptus and foetal cardiac activity were observed 32 or 46-49 days post-insemination. These results indicate that the low specificity of the real-time ultrasonic method is because of different disorders which may occur during pregnancy and that this technique is of great value in evaluating reproductive failure.