Exploring Morphometric Features of the Female Reproductive Tract in Brazilian Pantanal Cattle

Abstract

The cattle in the Pantanal region show a notable influence from Bos indicus breeds and their crossbreeds. However, a comprehensive biometric assessment of the reproductive system in these animals is currently lacking. This study evaluated the effects of breed, age, carcass weight, and estrous cycle phase on female reproductive system morphometry. A total of 124 healthy, non-pregnant reproductive tracts (83 Nelore and 41 Crossbred) were collected at a slaughterhouse. Neither the volume and weight of the ovaries nor the majority of uterine dimensions were affected by breed. Compared to heifers, cows showed longer uterine horns, a larger external caudal diameter of the uterine horns and body, and a greater external cranial diameter and internal caudal diameter of the cervix. The carcass weight (below vs. within commercial weight) affected the length of the uterine horns, uterine body, and cervix. Ovaries with a corpus luteum presented higher volume and weight than those with only follicles. Although the uterine measurements in the luteal phase were increased, the cycle stage did not affect the uterine morphometry. The average number of cervical rings was 5.0, independent of weight or breed. Crossbred animals presented a higher first cervical ring. Age didn´t influence the number, height, or distance between cervical rings. Deviation from the normal alignment of the cervix was recorded in 14.29 % of the animals, with a higher occurrence among Nelore cattle; deviation from the median axis was the most common (30%). This study emphasizes various parameters influencing the morphometry of the female reproductive system in Nelore cattle and their crosses, which could be crucial for implementing reproductive biotechnology techniques better suited to the morphological characteristics of zebu breeds