[Results and experiences of a two-year investigation in the use of sonographic pregnancy control in sows at different stages of gestation].

This paper presents the results of 16,592 pregnancy diagnoses in 4086 gilts and 12,506 sows. The animals were scanned transcutaneously between days 20 and 110 after mating or insemination (m/i). Animals being obviously pregnant or nonpregnant were scanned once, whereas sows which could not be recognized definitely as pregnant or not were characterized as animals with equivocal status and examined once again seven to 14 days later. Between days 20 to 23 after m/i pregnant sows were obviously identified to 99.5% (3336/3352). Nonpregnant sows were clearly recognized to 97% (3145/3243) between days 20 and 28 after m/i. Beginning on days 26 and 32, respectively, and later in gestation, pregnant and nonpregnant sows could be diagnosed to 100%. Confirmed through the re-examination, altogether nine (of 16 ambiguous pregnant sows) and 19 (of 97 ambiguous nonpregnant sows) animals were diagnosed false pregnant and nonpregnant, respectively. To avoid incorrect diagnoses or assessments, numerous phenomena should be attended. On days 20 to 23 after m/i, sows which did not establish pregnancy often show middle- or nonechogenic areas in the uterus and/or between the uterus loops. Since this can hardly be distinguished from pregnant uterine structures, it is recommended to examine the ovaries as well. Pregnant animals with signs of embryonic death should be grouped separately and examined twice, because it is unpredictable whether the pregnancy will stay intact or not. In conclusion, the ultrasonography is well suitable to detect pregnant and nonpregnant sows and can be applied very early in gestation.