Sonogram of coccygeus muscle in dairy cows with different gestational ages.

Background: The change in size and weight of the female reproductive organs during gestation and birth might be affect the perineal muscles and this condition in dairy cow not been reported. This study aimed to assess the ultrasonographic image of coccygeus muscle in 11 inseminated dairy cows with different gestational ages and postpartum.

Methods: Gestational age was calculated based on the record of artificial insemination and confirmed by using transrectal brightness mode ultrasonography. Perineal hair between the sacrum and ischium bones was shaved along 3-5 cm before being ultrasound. The images of perineal area were obtained by transcutaneous ultrasound using a 5.0 MHz transducer. The thickness and intensity of the coccygeus muscle were measured and analyzed by gestational status and postpartum to show the differences.

Results: The results showed that the thickness of coccygeus muscle increased with the increase in gestational age. Muscle intensity only increased at young gestational age. However, it decreased with the increase in gestational age ( P  < 0.05).

Conclusions: The ultrasound image of coccygeus muscle was affected by gestational status, thus this method may be used as one of the new methods of indirect gestational detection on dairy cows.