Steps for ultrasound examination of sheep
Sheep pregnancy
The average gestation period of ewes is 150 days (144-152 days for sheep and 147-155 days for cashmere goats). The expected date of delivery is the month of mating plus 5.
30 to 50 days after mating is the best time to diagnose early pregnancy in sheep through rectal exploration. The fetal sac in the uterus of about (8-12) × (12-16) mm and the fetus can be detected at 20-25 days of pregnancy; the fetal heartbeat can be detected at 25-30 days; after 30 days, the fetal sac, fetus and fetal heartbeat are very clear. The fetal membrane can be detected at 30-40 days; after 40-60 days of pregnancy, many cotyledon structures can be easily detected. At the same time, through abdominal wall exploration, the number of fetuses can be determined based on the number of fetuses detected and different fetal heartbeat frequencies within 50-80 days of pregnancy.
Selection of ultrasound equipment for sheep
Ultrasound examination of sheep uses a 3.5MHz convex array probe to scan from the right posterior abdominal wall to the opposite posterior and upper side (the exploration effect is better after shaving) and a 6.5MHz (or higher frequency) linear array rectal probe to scan downward through the rectum. The sheep should be fasted for 24 hours before exploration, because when the sheep is fully fed, the inflated intestinal tube will be squeezed to the posterior abdomen, affecting the cross-sectional observation. At this time, press the probe hard to squeeze the inflated intestinal tube.
Inspection steps
1. Preparation: Place the ewe in an appropriate position, either standing or lying down, and prepare the B-ultrasound machine and the corresponding probe.
2. Apply coupling agent: Apply coupling agent to the inspection site or probe.
3. Inspection process: Place the probe in the hairless area between the ewe's hind legs and udder, and start moving the probe to scan the entire abdominal area. The ultrasound machine generates a real-time image through the ultrasonic waves emitted by the probe and the reflected signals.
4. Observation image: For non-pregnant ewes and ewes within 25 days of pregnancy, the uterus is located in the pelvic cavity, the uterine body is in the center above the bladder, and the two uterine horns are vertical to the front and lower sides of the bladder. At 15 days of pregnancy, the fetal sac is spread out in a thread-like manner, 100-150mm long, and is located in the uterine horn on the same side as the corpus luteum. At 17-20 days, the fetal sac extends to the opposite uterine horn and is filled with liquid.
The uterus and ovaries of young ewes are small, and due to the interference of the inflated intestine, it is difficult to show clearly during surface exploration; only when pregnant.
The role of ultrasound in animal husbandry
1. B-ultrasound can be used for the identification of twins or multiple births, providing a scientific basis for fetal protection and improving reproduction rate.
2. B-ultrasound can be used for early diagnosis of pregnancy in cattle and sheep, examination of fetal development and determination of gestational age - timely and correct diagnosis after mating, implementation of fetal preservation and nutrition plans for pregnant cattle and sheep; timely mating of non-pregnant cattle and sheep, thereby reducing empty foetuses, increasing reproduction rates, reducing ineffective feeding, and thus improving economic benefits.
