Reproductive features of PRRS-convalescent large white pigs after porcine reproductive and respiratory syndrome

Abstract

Most sows convalescent from porcine reproductive and respiratory syndrome (PRRS) are immune to the re-infection. The PRRS virus's antibodies detected by enzyme-linked immunosorbent assay (ELISA) can persist for a year. The PRRS virus (PRRSV) causes damage to the pigs' reproductive system, manifested by abortions, delivery of non-viable piglets and saws' infertility. We carried out morphometric studies of recovered pregnant pigs' reproductive organs to determine changes in the fetus and placenta system in pregnant PRRS-convalescent sows. Morphological studies of the fetal portion of the placenta indicate that the weight of the placenta in PRRS-convalescent sows was significantly lower as compared to the weight of the placenta in clinically healthy pregnant sows, 0.71 ± 0.05 kg versus 0.92 ± 0.09 kg at the end of the second trimester, and 1.61 ± 0.42 versus 1.75 ± 0.16 kg on day 105-110 of gestation. By day 70-75 of gestation, we observed a significant 31.8%-decrease in the fetus's body weight in seropositive pigs compared to the clinically healthy ones and 19.2%-decrease on days 105-110. Piglets born from the experimental sows demonstrated physiological abnormalities that allowed for hypotrophy diagnosis. ELISA-tests of sera for anti-Müllerian hormone (AMH) proved the possibility of early assessment of gilts' fertility. This method will enable the premature culling of low-yielding replacement gilts from the breeding stock. Further development of the methods for gilts' fertility determination and ELISA-testing for AMH during the mandatory gynecological screening of the gilts at the pig breeding establishments are economically practical and effective.