DETERMINATION OF EARLY-PREGNANCY AND EMBRYONIC GROWTH IN GOATS BY TRANSRECTAL ULTRASOUND SCANNING

Ultrasonography has been shown to be a useful tool for pregnancy diagn osis and the study of embryonic growth in mammals. The objectives of t his study were 1) to evaluate the use of real-time B-mode ultrasonogra phy for early pregnancy diagnosis in goats, 2) to define criteria for accurate diagnosis of pregnancy, and 3) to monitor the embryonic growt h ultrasonically until Day 40 after mating. Estrus was synchronized in 16 cyclic Anglo-Nubian goats with a single injection of cloprostenol (125 mu g, im). Estrous females were randomly assigned into 2 groups: 1) goats mated by a vasectomized male (n=5; MV group), and 2) goats ma ted by an intact male of proven fertility (n=11; MF group). Transrecta l ultrasonographic examinations with a 5 MHz linear array transducer w ere performed from Days 13 to 40 post mating. The evaluated parameters included the appearance of nonechogenic areas in the uterus, presence of embryo(s), crown-rump length of embryo and embryonic heart rate (b eats/min). On Day 18, the mean (+/-SEM) diameter of nonechogenic areas was 1.5+/-0.3 mm in the MV group and 4.0+/-0.5 mm in the MF group (P< 0.01). In 36% of the pregnant does these areas were less than 3.mm. Th e mean (+/-SEM) day of the first detection by means of heartbeats of a t least 1 embryo was 20.7+/-0.5 d (range, Days 19 to 23). From Days 19 to 38 of pregnancy, crown-rump length was best represented by a linea r regression (Y = -2.23+0.13X; r(2)=0.94; P<0.05). Crown-rump length o n the day of the first detection of an embryo was 5.3+/-0.3 mm, reachi ng 34.2+/-0.6 mm on Day 40. Mean (+/-SEM) heartbeat rate was 168.3+/-2 .8 beats/min on Day 21, decreasing to 158.3+/-2.0 beats/min on Day 40. Detection of the caprine embryo by ultrasonography and confirmation o f its viability by heartbeats was shown to be a reliable method for ea rly pregnancy diagnosis in Anglo-Nubian goats. Ultrasonic measurement of crown-rump length was useful in predicting the age of the embryo. ( C) 1998 by Elsevier Science Inc.