Analyse des stéroïdes dans la salive de cochettes pour identifier des biomarqueurs de la période de réceptivité à l’effet mâle

National audience; Our objective was to develop alternatives to hormonal treatments to synchronize oestrus of gilts. Before puberty, gilts experience a pre-puberty period during which boar exposure could induce and synchronize the first ovulation. To develop practical non-invasive tools to identify this period and improve detection of the gilts to stimulate, we searched for salivary biomarkers of the pre-puberty period. Saliva samples were collected from 30 Large-White x Landrace crossbred gilts from 140 to 175 days of age. Gilts were exposed to a boar twice a day and subjected to oestrus detection from 150 to 175 days of age. They were then slaughtered to ascertain puberty. Among the 30 gilts, 10 were detected in oestrus 4 to 7 days after introduction of the boar and were considered receptive to the boar effect, 14 were detected in oestrus more than 8 days after boar introduction, six did not show oestrus before slaughter and were considered non-receptive. Salivary steroidome analysis was performed for six receptive and six non-receptive gilts using gas chromatography coupled to tandem mass spectrometry. Four saliva samples per gilt were analysed: 26 days and 11 days before boar introduction (day0-26 and day0-11), the day of boar introduction (day0), 3 days later for receptive gilts (day0+3) or 7 days later for non-receptive gilts (day0+7). Saliva analysis detected 30 steroids. The concentrations of six of them were higher (P < 0.05) in receptive gilts than in non-receptive gilts at day0-26 (progesterone), day0-11 (3α5β20α-hexahydroprogesterone, 3β5α20β-hexahydroprogesterone, dehydroepiandrosterone, androstenediol) and day0 (3β5α-tetrahydroprogesterone). Their low and variable concentrations in saliva require expensive analysis and limit their use in pig farms. However, progesterone could be an interesting biomarker of the pre-puberty period.