Effect of Estradiol Benzoate on the Size of Follicle and Corpus Luteum of Holstein Cows Treated with D-Cloprostenol

The effect of two treatments, farms, and body shape on the size of the follicle and Corpus Luteum were evaluated. D-Cloprostenol (150 ug) was used in one of the treatments; in the other, D-Cloprostenol (150 ug) and Estradiol Ben-zoate (1 mg), were used. Two groups of 32 Holstein dairy cows each, from the Nero and Irquis farms in Cuenca, Ec-uador, were set up. Body condition (2.75-3.50) was considered. The calving number was 1-6; the farms, Irquis and Nero; and animal age, 3-10 years. Ultrasound scanning was used on days 0; 3 and 7, in order to measure the Luteum first, then the dominant ovarian follicle, and finally, the Corpus Luteum. Factor analysis of variance was performed. No significant differences were found for follicle size due to any factors; nor due to interaction. Concerning luteum, significant differences (P < 0.05) were observed for the treatments and for the farm. The values were 0.33 cm higher for the treatment with Benzoate, and 0.36 cm, at Irquis, in comparison to Nero. The treatment with Benzoate, along with better husbandry at Irquis played a critical role in the appearance and evolution of the luteum.