Blood Collection and Progesterone Assay
Starting on Day 11 of the estrous cycle, blood samples (5 ml) were taken twice daily (0930 and 1730 h) until the next expected estrus so that progesterone could be analyzed. After each blood collection, the catheter was filled (5 ml) with a saline solution containing 50 IU/ml of heparin (Leo S.A.; St Quentin en Yvelines, France). Blood samples were immediately heparinized and centrifuged, and plasma was stored at — 20°C until analysis. Plasma progesterone concentration was measured by RIA as described by Sau-mande et al.. From this series of plasma samples, those corresponding to Days 14 and 15 postestrus were also assayed for IFN-7 by ELISA and for total antiviral activity on MDBK cells. buy diabetes drugs
Detection of Estrus
Detection of estrus was performed twice daily after blood sampling in the absence of a boar to avoid problems with uterine catheters. The estrous behavior of Meishan gilts, although very different from that of European breeds, is very pronounced and easy to detect without a boar. The occurrence of estrus was based on the following parameters: swelling and reddening of the vulva, moving and typical grunts of the female, and standing reflex (human backpressure). The beginning of estrus was defined as the first standing reflex with the other parameters supporting this.