RESUMO
The objective of this study was to reduce the effects of cryoinjury caused in bovine semen by cryopreservation. Ejaculates were collected from Nellore bulls and subjected to freezing in C (control), ozone (15, 30, and 60 µg mL-1 of ozone), quercetin (25, 50, and 100 µg mL-1 of quercetin), and carnosine groups (100, 200, and 300 ng mL-1 of carnosine). Samples were evaluated post-thaw (M0) and post-rapid thermoresistance test (M30) for sperm kinetics (total motility, progressive motility, curvilinear speed, linearity and amplitude of lateral head displacement) and cell structure viability (plasma membrane integrity, acrosomal integrity, mitochondrial potential, membrane fluidity, and lipid peroxidation). There were no differences (P > 0.05) between the control, quercetin, and carnosine-treated groups for the parameters evaluated at M0 and M30. In turn, supplementation with ozone resulted in lower values for sperm kinetics (P < 0.05) and lower mitochondrial potential at M30 (P < 0.05). Quercetin and carnosine at the concentrations used did not promote significant gains in frozen semen, nor did they demonstrate cytotoxicity. We expected to obtain positive results with the use of ozone. Nonetheless, the addition was harmful to the parameters of sperm kinetics, and its effect was not observed as a possible pro-antioxidant. We believe that the fact that the gas did not harm the sperm structure opens avenues for tests with lower dosages, since, by reducing its concentration, we could minimize the damage to sperm kinetics.
RESUMO
Dispersed ovulation at the breeding (BS) and anestrus at non-breeding season (NBS) are major impediments to embryo transfer and insemination programmes. The present study aimed to evaluate a hormonal P4/E2-based synchronisation protocol in mares during both the BS and the NBS on ovarian/follicle behaviour. Mares underwent a hormone protocol to synchronise their ovulation during the BS (n = 8) and NBS (n = 10), starting (D0) with the insertion of an intravaginal device containing 1 g of P4 and 7 mg Estradiol Benzoate IM. (EB). On D9, the device was removed and injected with 0.25 mg of cloprostenol sodic IM and 2 mg of EB IM. Follicular behaviour was evaluated using a daily transrectal ultrasound (24/24 h) from D0 until ovulation. When the dominant follicle (DF) measured at least 35 mm, females were injected with 0.25 mg of gonadorelin acetate IM to induce ovulation. The DF on D0 were similar in animals between BS (18.9 ± 8.4 mm) and NBS (23.7 ± 9.2 mm; p = 0.2700). However, in the BS the DF was smaller (14.2 ± 4.7 mm) on D9 than during NBS (22.0 ± 7.1 mm; p = 0.0177). During the BS, the ovulatory follicle is smaller (p = 0.0042) than during NBS, measured at 33.5 ± 4.6 mm and 41.3 ± 2.8 mm, respectively. Ovulation time after P4 removal was similar during BS (173.1 ± 68.8 h) and NBS (192 ± 58.2 h; p = 0.3507). There was no difference towards an ovulation rate during BS (88%) and NBS (60%; p = 0.0978). There was no difference in spontaneous ovulation during BS (43%) and NBS (0%; p = 0.6085). This hormonal protocol would be an effective tool for inducing cyclicity/ovulation in mares during BS and NBS.