Morphological characteristics of pelves of estonian holstein and estonian native breed cows from the perspective of calving.

Dystocia is more common in Holstein-Friesian (HF) breed cows than in other dairy breeds. This is often caused by a disproportion between the birth canal of a female animal and the fetus. It is thought that the main determiners of unsuitability are the birth mass of the calf and the shape of the female pelvis. From the perspective of calving the cranial and caudal pelvic apertures are of great significance. This study focuses on pluriparous pelves of the Estonian Native Breed (EN) and the Estonian Holstein Breed (EHF). The longest measurement of the cranial pelvic aperture of an EHF cow is the conjugate diameter. The cranial pelvic aperture narrows slightly ventrally, being shaped like a trapezium with rounded angles. The longest measurement of the caudal aperture is its caudal transverse measurement. The aperture is flattened dorsoventrally. The cranial pelvic aperture of an EN cow is dorsally angular, but more oval ventrally, and is on the whole narrower and higher. By comparison with the EHF cow, the pelvic cavity of the EN cow widens caudally, and the height of the pelvic apertures contributes to ease of calving. It appears that the configuration of the pelvis of an EN cow is similar to the pelvis of the elk (Alces alces). The pelvis of the EHF cow has become unsuitable for easy calving, especially with regard to the caudal aperture.