The Clinical Findings of Ovarian Dysfunction in Dairy Cows

Abstract

Ovarian disjunction is a serious cause of reproductive failure in dairy cows. The present investigation was aimed at studying the clinical findings associated with their disorders. Ovarian subfunction in 5 cows were diagnosed one month following the last carving. In 3 out of 5 cows, ultrasonography over a 3 week period revealed a wave-like pattern follicular growth in the ovaries. Plasma progesterone (P4) concentration was determined by enzyme-immunoassay. Four cows had P4 of less than 1.0 ng/ml during the experimental period. However, one cow in this group had a corpus luteum during clinical examination and P4 level also increased later. The ovulatory failure in 5 cows were diagnosed by rectal palpation following 2 or 3 services among estrous days. Ultrasonography also showed the presence of follicles >1.5 cm in diameter in the ovaries. Two cows in this group had a hyper-echoic corpus luteum in addition to follicles 1.0-2.0 cm in diameter. Their P4 level were 1.5, 3.5 ng/ml, respectively. However, ultrasonography failed to show a Graafian follicle and an altertic follicle. Three cows with ovarian follicular cysts which showed nymphomaniac syndrome were diagnosed by ultrasound. Cystic follicles in all 3 cows had a wave-like pattern of growth and regression for 20 days similar to ovarian follicular wave. However, the granulosa layer and/or altered cystic follicular structure could not be imaged in all cases. Twenty days after first observation, the cows were treated with hCG 10,000 IU, intramuscularly. In 2 cows, P4 level increased to more than 1.0 ng/ml after treatment 3 days. The results indicates that cows with ovarian subfunction and follicular cysts have follicular wave in ovaries similar to a normal cycle. However, the degenerative changes and subsequent shedding of granulosa cells from the follicular wall which led to the ovulatory failure in the cows could not be imaged by ultrasound.