DETERMINATION OF GESTATIONAL-AGE IN SHEEP AND GOATS USING TRANSRECTALULTRASONOGRAPHIC MEASUREMENT OF PLACENTOMES

Three experiments were conducted to determine gestational age in the e we and doe by measuring placentomes with a B-mode ultrasonograph and a 5 MHz transducer. Transrectal measurements were obtained by placing t he female over a bale of hay. In Experiment 1, ewes (n = 12) and does (n = 15) were examined by transrectal ultrasonography every week from breeding to parturition to determine the growth pattern of placentomes during pregnancy. In Experiment 2, placentomes from 132 ewes and 169 does were measured between 30 and 90 d of gestation. A linear regressi on relationship between fetal age in days and placentome size in mm wa s calculated and adjusted for does (gestational age = 28.74 + 1.80PL e, r(2) = 70.34) and for ewes (age = 47.98 + 0.62PL + e, r(2) = 15.59 ). In Experiment 3, the placentomes of 63 does were measured to valida te this relationship by using linear regression. Gestational age was d etermined correctly in 66% of the does, with a range of +/- 7 d and in 96% with a margin of +/- 14 d. In conclusion, transrectal ultrasonogr aphy allowed for the measurement of placentome size, which increased r apidly during the first 70 to 90 d of gestation in ewes and does. In e wes, however, there was a poor correlation of placentome size with ges tational age, while in gears, measurement of placentomes could be used along with pregnancy diagnosis by transrectal ultrasonography as an i ndication of gestation age. (C) 1997 by Elsevier Science Inc.