Ultraljud vid tidig dräktighetsdiagnostik på nötkreatur : en fältstudie för att bestämma lämplig undersökningsdag och frekvens på ultraljudsproben

Abstract: The use of transrectal ultrasonography of the uterus is a fairly new method for early pregnancy diagnosis. In the present study 40 cows and 10 heifers were examined 16, 19, 22 and 25 days after artificial insemination to decide on what day an accurate pregnancy diagnosis could be made under field conditions. A 5 and 7,5 MHz transducer were used in all examinations in order to determine wheter one of them was better for the present purpose. The animals were also examined for clinical signs of oestrus. The results shows that an accurate pregnancy diagnosis "not pregnant" was easier to make on day 22 than on day 25 since most of the not pregnant cows then were in heat. Because of the low number of not pregnant heifers, it was not possible to determine what day these were easier to diagnose. The pregnant animals were easier to diagnose at day 25 because of more fluid in the uterus. Hence, it was not possible to decide a single day for most accurate diagnose of both the pregnant and not pregnant animals. The 5 MHz transducer was better than the 7,5 MHz transducer to make accurate pregnancy diagnosis under field conditions. The incorrect diagnosis "pregnant" in non pregnant animals was more often made by the 7,5 MHz transducer compared to the 5 MHz transducer, since the higher frequency of the transducer gives less tissue penetration.