Evaluation of progesterone device reuse in shortened ovulation synchronization protocol in buffaloes raised in Amazon

This study aimed to assess the viability of reusing progesterone (P4) intravaginal device to synchronize the follicular development wave in buffaloes in a shortened ovulation synchronization protocol. Fifteen female buffaloes aged between 4 to 7 years, with body condition scores ranging from 3 to 4 (on a scale of 1 to 5), were utilized in a switch-back design experiment conducted over three periods. Each treatment was applied three times in each period, resulting in 45 experimental units. The buffaloes underwent three consecutive protocols with a 10-day interval between each protocol. Treatments were: a new 2 g intravaginal progesterone device (P4) (GNew) and devices previously used for 7 (G7), 14 (G14), 21 (G21), and 28 (G28) days. Additionally, on Day 0, intramuscular administration included 2 mg of estradiol benzoate (EB) and 150 μg of sodium cloprostenol. On day 7, the removal of the P4 intravaginal device was performed, and cows received IM 150 μg sodium cloprostenol and 1.0 mg of estradiol cypionate. To determine serum P4 levels, blood samples were collected from all females in the experimental groups on days 0, 2, 4, and 7. The buffalo cows were submitted to ovarian ultrasound examinations on alternate days to ascertain the diameter and area of ovulatory follicle. Treatments GNew, G7, and G14 showed a tendency to induce the formation of large persistent follicles, identified as follicular cysts, in contrast to treatments G21 and G28. The use of P4 devices previously utilized for up to 28 days in a short ovulation synchronization protocol successfully induced concentrations above 1 ng/mL during P4 exposure, effectively preventing ovulations in buffaloes under Amazonian conditions. Notably, there are indications that concentrations exceeding 1.5 ng/mL was linked to the observed high incidence of follicular cysts in the experimental groups. In conclusion, the study suggests that the use of P4 intravaginal device with low content proves to be more efficient in synchronizing the follicular wave in buffaloes. This information contributes to our understanding of reproductive efficiency in Bubalus bubalis, particularly in the unique conditions of the Amazon.