[Determination of progesterone in peripheral blood-plasma as a diagnostic aid in female swine (author's transl.)].

The determination of the peripheral plasma level of progesterone was evaluated as a clinical aid in the gynaecological diagnosis of female pigs. The normal cyclic variation of the peripheral plasma level of progesterone was determined in six cross bred gilts (Swedish Landrace times Swedish Yorkshire Breed) which were examined daily for the stages of oestrus. The results of this investigation are given in fig. 1. Peripheral plasma levels of progesterone were determined in 16 gilts with the clinical diagnosis of "silent heat". Despite all 16 gilts being sexually mature none of them had shown clinical signs of heat. The gilts belonged to 3 different farms, on all of which there was a high incidence of "silent heat". At least two blood samples were drawn 7 days apart from each of the gilts. Of the gilts examined 12 had variations in peripheral plasma level of progesterone. Of these 12 animals only 5 had clinical signs of heat, although the farmer had been advised, from the progesterone analysis, on the probable day of occurrence of heat. In 3 of the gilts, treatment with hormones (PMSCG) elicited the standing reflex when they were placed with a boar. In Table I is given some examples of the relationship of clinical signs of heat and the peripheral plasma level of progesterone. The peripheral plasma level of progesterone was also used as an early pregnancy diagnosis test in gilts. The gilts used in this investigation were all artificially inseminated with deep frozen boar semen. The expected pregnancy rate after insemination was 50%. Blood samples were drawn 17-25 days after insemination of 84 gilts. Peripheral plasma level of progesterone equal to or higher than 7.5 ng/ml were considered to indicate pregnancy. All gilts were slaughtered 4 weeks after the insemination and the number of fetuses were counted. A correct pregnancy diagnosis by the estimation of peripheral plasma level of progesterone was obtained in 95.2% of the gilts. The incorrect diagnoses were all false positives, viz. non-pregnant gilts were diagnosed as pregnant.