Estimation of Salivary Progesterone Levels for Early Diagnosis of Pregnancy in Pigs

Profitable pork production can be achieved by not only enhancing the breeding efficiency but also by accurate detection of pregnancy for rebreeding the non-pregnant sows and/or culling the non-performing females. Therefore, a reliable and accurate pregnancy diagnosis method post-service is the need of the hour in swine production. The aim of the current study was to determine if measurements of salivary progesterone, alternative to serum progesterone, could be used for pregnancy diagnosis in sows. Progesterone levels in both saliva and serum samples of day 10 and day 21 post-service and non-pregnant animals were estimated using a competitive enzyme immunoassay. Both serum and salivary progesterone levels among non-pregnant and pregnant (day 10 and 21 post-service) sows were significantly different (p<0.0001). The progesterone concentration in saliva on day 21 post-service was found to be more than 2 ng/mL. Moreover, a significant difference in ratio of saliva:serum progesterone levels was observed between non-pregnant and pregnant (day 10 and 21) animals. The findings of the present study support the hypothesis of pregnancy diagnosis based on salivary progesterone levels in sows as revealed by the course of salivary levels of progesterone in early gestation period. This study forms an essential step in diagnosing pregnancy status based on progesterone levels in saliva instead of serum and could be regarded as a pilot reference study, results of which could benefit similar studies in the future. Blood and saliva samples were collected from sows (6 LWY) on day 10 and day 21 post service and also from non-pregnant sows (6 LWY; on day 5 post-weaning) serving as controls. The collection of saliva samples was carried out using cotton swabs. Both saliva and serum samples from sows of day 10 and day 21 post-service were considered for further studies only after their farrowing. All the animal experiments were carried out strictly as per the guidelines issued by Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA), Ministry of Environment, Forests & Climate change, Government of India and was approved by Institute Animals Ethics Committee (IAEC) of College of Veterinary Sciences and Animal Husbandry, Central Agricultural University, Aizawl,