The efficiency of in vitro maturation (IVM) in Cavia porcellus remains suboptimal compared to other species. This study aimed to characterize the morphological and functional quality of oocytes based on the stage of the estrous cycle and the classification of the cumulus–oocyte complexes (COCs) from which they were derived. A total of 744 oocytes were recovered postmortem from females in the diestrus and periovulatory phases. Oocytes were evaluated for metabolic activity, lipid distribution, apoptosis, nuclear maturation, and diameter. Oocytes collected during diestrus exhibited larger diameters and more homogeneous lipid distribution, particularly in oocytes from Type A COCs. In contrast, a higher proportion of BCB+ oocytes and reduced rates of early apoptosis were observed during the periovulatory stage, suggesting enhanced metabolic competence. Nuclear maturation rates varied with both cycle stage and COC classification, with oocytes from Type A COCs showing higher maturation rates in diestrus. These findings indicate that both intrinsic (e.g., morphological quality) and extrinsic (e.g., estrous cycle stage) factors modulated oocyte competence. Selecting oocytes based on integrated morphological and physiological criteria may improve the efficiency of IVM protocols in this species.

El objetivo del presente estudio fue valorar la prueba del azul brillante de cresilo (BCB) como método indirecto para seleccionar ovocitos competentes para la producción in vitro de embriones (PIV). Los complejos cúmulos-ovocitos (COC) fueron obtenidos de dos vaquillas criollas sometidas a dos tratamientos: T1 = COC recuperados por OPU (ovum pick-up) previa estimulación con FSH-LH; T2 = COC recuperados sin previa estimulación de la donante (testigo). Las dos vaquillas fueron alternadas en los dos tratamientos y se hicieron cinco repeticiones. Los COC recuperados fueron clasificados en tipos A, B, C y D. Luego se aplicó la prueba del BCB a cada uno de los tipos de COC para determinar si son BCB+ o BCB-. T1 permitió recuperar 5.2 más COC que T2 (p<0.05). Al aplicar la prueba del BCB se determinó que todos los ovocitos tipo A de T1 y T2 fueron BCB+; es decir, terminaron su crecimiento y se encontraban listos para iniciar el proceso de maduración in vitro; sin embargo, solo alrededor del 50% de los COC tipo B, C y D de T1 y T2 fueron BCB+. Se concluye que la selección de COC basado en las características morfológica es un método confiable únicamente para los de tipo A, y tiene un 50% de error para los COC de tipo B, C y D y, por lo tanto, la aplicación de la prueba del BCB permite mejorar esta selección de forma no invasiva.

This study evaluated the effects of serum (egpS) and follicular fluid (egpFF) from estrus guinea pigs as in vitro maturation (IVM) supplements for natural cycle guinea pig oocytes. Two experiments were conducted: the first assessed three IVM media, a commercial medium (CMOM) and two homemade media (HMOM-P and HMOM-S), for oocyte in vitro maturation using 615 bovine oocytes, while the second evaluated the incorporation of 5%, 10%, and 20% egpFF or egpS into IVM media for 1744 guinea pig oocytes. Initially, we optimized the IVM base medium using bovine oocytes to determine the most suitable culture conditions. The results obtained from these experiments served as a critical foundation for subsequent supplementation trials conducted with guinea pig oocytes. The oocytes were cultured in 70 μL drops under controlled atmospheric conditions, and maturation rates were assessed based on cumulus cell expansion and nuclear progression. The HMOM-S medium significantly enhanced cumulus cell expansion (72.5 ± 2.88%) compared with the CMOM medium (57.7 ± 5.33%; p < 0.05). Supplementation with egpFF at 5% (68.8 ± 6.22%), 10% (76.3 ± 5.39%), and 20% (80.9 ± 6.22%) significantly improved both cumulus cell expansion and nuclear progression in high-quality oocytes (types A and B), compared to the control group (43.3 ± 4.82%). Conversely, supplementation with egpS did not have a significant effect on cumulus cell expansion (p > 0.05); however, it notably improved nuclear maturation in low-quality oocytes (type C) at concentrations of 10% and 20% (p < 0.05). This resulted in an overall improvement in maturation outcomes, particularly for oocytes with compromised initial quality. These findings demonstrated that the IVM of guinea pig oocytes using HMOM-S medium was significantly enhanced by the presence of egpFF, whereas egpS supplementation exhibited a less pronounced effect on IVM outcomes.

Implementing alternatives methods to dorsal massage (e.g., electroejaculation) for recovering semen from fighting rooster, known to be very stressful due to its aggressiveness, has become a priority for breeders of this cock breed in Ecuador. Therefore, the objective of the present study was to evaluate two semen collection techniques in fighting roosters, one by electroejaculation (EE) and another by dorsal massage (DM) on seminal quality parameters. For this purpose, thirty attempts of semen recovery from six adult Spanish fighting roosters were carried out using DM (n = 12) and EE (n = 18). Electroejaculation was performed previous sedation, applying five stimulation cycles (of 2 s) generated from a handmade electroejaculation probe (9 to 12 V). The results showed that the EE produced lower response (P < 0.01) to semen ejaculation than the DM (44.4 % vs. 100.0 %, respectively). However, semen samples obtained by EE had better (P < 0.05) spermatic kinetic with greater values of straight-line velocity (VSL, µm/s), average path velocity (VAP, µm/s), and beat-cross frequency (BCF, Hz) as well as higher percentages (P < 0.01) of wobble and linearity compared to DM, irrespective of sperm viability. In addition, the number of urates present in the ejaculates obtained by EE was lower (P < 0.05) than those obtained by DM. In conclusion, electrical stimulation with prior sedation produced a low semen ejaculation response in fighting cocks. However, EE yielded semen ejaculates with better spermatic kinetic compared with the conventional dorsal massage technique.