Relationships between antral follicle count, body condition, and pregnancy rates after timed-AI in Bos indicus cattle

• Published in: Theriogenology 2019-09, Vol.136, p.10-14
• Main Authors: de Moraes, Fábio Lucas Zito, Morotti, Fábio, Costa, Camila Bortoliero, Lunardelli, Paula Alvares, Seneda, Marcelo Marcondes
• Format: Article
• Language: English
• Subjects: Animals; Antral follicle count; Body Composition - physiology; Body condition score; Cattle; Female; Insemination, Artificial - veterinary; Ovarian Follicle - physiology; Pregnancy; Pregnancy Rate; TAI
• ISSN: 0093-691X; 1879-3231
• DOI: 10.1016/j.theriogenology.2019.06.024

An experiment was performed to evaluate the association between the antral follicle count (AFC) plus body condition score (BCS) and the pregnancy rate in Bos indicus undergoing timed artificial insemination (TAI). A total of 736 Nelore cows with BCSs ranging from 2 to 4 received a conventional protocol for TAI. On a random day of the estrous cycle (Day 0), all cows received an intravaginal P4 device and an intramuscular (i.m.) injection of 2.0 mg estradiol benzoate. On Day 8, the P4 device was removed, and 150 μg sodium D-cloprostenol, 300 IU equine chorionic gonadotrophin and 1.0 mg estradiol cypionate were administered by i.m. injection. TAI was performed 48 h after P4 device removal, and pregnancy diagnosis was performed by ultrasonography after 30 days. On Day 0, all cows were examined by ultrasonography to determine the AFC by counting the number of follicles >3 mm in diameter that were present in both ovaries and to evaluate the BCS (scale of 1–5). The cows were then classified based on their AFCs as those with low (≤10 follicles), intermediate (11–29 follicles) and high AFC (≥30 follicles). Furthermore, cows were classified as having low (≥2.0 to ≤ 2.9) and high (≥3.0 to ≤ 4.0) BCSs. The AFCs and BCSs were analyzed using the generalized linear model, and the pregnancy rate was assessed with the binary logistic regression model (P ≤ 0.05). The pregnancy rate was influenced (P