author(s)
Kancharla Jyothi, Guelal Sudha, Kosaraju Mouli Krishna, Annayappa Sahadev, Muniyappa Narayana Swamy, Suguna Rao and Manepanda Appaiah Kshama

abstract
Detection of gestational age helps in nutritional management of pregnant ewes and optimizes the lamb survival. Nellore Brown ewes (n=20) aged 1-4 years were subjected to short day estrus synchronization protocol by inserting vaginal sponges and received 300 IU of PMSG and 75 µg of PGF2α intra muscularly at sponge withdrawl and matings were monitored. The last day of receiving mating mark was treated as day 0 start of pregnancy. Transabdominal ultrasonography weekly once starting from day 8 onwards until parturition. On day 29, in more than 50% of pregnant animals placentome were observed as raised, nodular, convex shaped that projected into the lumen of uterus. The cup shaped placentome were first observed on day 36 and by day 43 in all ewes cup shape or C shaped placentomes were evident. Up to day 85 the placentomes were uniformly hyperechoic in texture. By day 92 the borders of placentomes started becoming more hyperechoic and within uniformly hypoechoic. As the gestation advanced the placentome hollowed out. Just before lambing the placentome widened and were distorted in shape. A moderately positive correlation was established for placentome length and gestational age between days 43 and 78 (r = 0.685; R2 =0.470). Using the regression equation developed for up to 78 days of gestation y = 11.87x + 34.13, 62 and 100% of pregnant ewes delivered within ±7 and ±14 days respectively of expected parturition dates. From this study it can be concluded that the echogenicity of placentome gives the rough estimate and progression of the gestation and the placentome length can be used to estimate gestational age in early pregnancy up to first half of the gestation in Nellore Brown ewes.