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Monitoring of early embryonic mortality in dairy cows using ultrasound and progesterone

Study of maternal interaction with embryo in early stage may be improved by using ultrasonography. This tool offers opportunity for noninvasive, highly accurate monitoring of the uterine and ovarian structures. Embryonic loss during first 42 days of pregnancy presents the major problem of decreased dairy cow fertility. It has been estimated recently that early embryonic mortality presents more than 50% of pregnancy failure in cattle (mostly before day 17). The aim of this study was to observe the influence of some characteristics of ovarian structures (CL diameter and progesterone profile) as a possible cause of infertility. For that reason Holstein-Friesian multiparous cows (n=27) were synchronised with PGF2 alpha and inseminated after oestrus was detected. Blood sampling and transrectal ultrasonography of ovaries and uterus were performed on day 15, 21, 26 and 31 after AI with 7, 5MHz rectal probe. Plasma samples were collected and analyzed for progesterone (P4) concentration by enzyme immunoassay (EIA) method on the same days. The cows were considered pregnant if CL diameter was ≥ 2, 5cm on day 21 (criteria after DOvenski, 1998). Twenty cows were considered pregnant with average CL diameter of 2, 58 ± ; 0, 06cm and P4 plasma level of 3, 85 ± ; 0, 28ng/mL respectively. Positive pregnancy diagnosis, based upon finding of an anechoic zone in the uterine lumen and a hyperechoic conceptus inside on day 26 and 31 was found in 17 cows (85%). P4 plasma level was 4, 11 ± ; 0, 47ng/mL. Differences in plasma P4 level between pregnant and non-pregnant animals were statistically significant (p=0, 0187) on day 15 (4, 3 ± ; 0, 35 ng/mL vs. 3, 11 ± ; 0, 36ng/mL), regardless of non-significant differences in CL diameter (2, 62 ± ; 0, 05 vs. 2, 63 ± ; 0, 97cm) respectively. Ultrasonography could be useful tool for detection of pregnancy loss in dairy cows ; however it is inefficient before day 21.

early embryonic mortality; cows; ultrasound; progesterone; CL diameter

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