Search

The research was carried out on a commercial farm Juticaray, located in the city of Cañar, at altitude of 3230 meters above sea level. The response to ovarian stimulation with 250 International Units (IU) of Follicle-stimulating Hormone (FSH) applied epidurally was evaluated in crossbred Holstein heifers (n=8) levels with high (42 days) and low (28 days) levels. of fiber in their diet, on ovarian response, assessed according to the number of antral follicles observed on the day of ultrasound-guided aspiration (OPU); number and quality of cumulus oocyte complexes (COC's) recovered by the OPU technique. Four treatments were established: T0=control (28-day pasture); T1=28-day grass + 250 IU of FSH; T2=control (42- day pasture); T3=42 day grass + 250 IU of FSH. The forage mixture consumed by the heifers was made up of 80.08% grasses and 7.4% mainly legumes. Crude fiber levels were similar between 28- and 42-day-old pastures (P>0.005); However, the 28-day grass had higher values of humidity, crude protein and ash compared to the 42-day grass (P<0.05). The overall average number of follicles visualized on the day of the OPU was 20 ± 1.07 follicles, 76% were aspirated (15.2 ± 1.11 follicles visualized) and 60.5% of COCs were recovered. (12.1 COC's), when classifying 56.2% were suitable and 43.8% were not suitable. The % recovery of COCs from T3 was 17.6% more compared to its control (T2) and 8.2% compared to T1. Furthermore, T3 obtained 3 times more suitable COCs compared to T2. It is concluded that administering 250 IU improves the number of aspirated follicles and the number and quality of recovered COCs, regardless of the phenological age of the grass that the heifers consumed.

The aimed of this study was to evaluate the effect of the administration of Human menopausal gonadotropin (hMG) in different doses on the ovarian response in guineapigs, with prior synchronization of the estrous cycle. A total of 18 female guineapigs with an average age of 80 ± 15 days, weight about of 800 to 1150 grams, were used, under to 10 days adaptation process. 3 experimental groups were formed, which were synchronized for 15 days with progesterone (P4); starting on the last day of P4 administration and for 3 consecutive days, hMG was administered intraperitoneally at different doses, 5, 10, and 15 IU/kg/day. The administration of hMG significantly increased the number of corpora lutea (CLs) in all groups, in addition to the total number of recovered structures; however, there were no significant differences in the number of CLs observed, on the surface of the ovary, or in the structures recovered between the different doses of hMG. The number of the structures classified as suitable was higher in all groups, likewise, the proportion between morulas and blastocysts considered suitable was different between groups, all groups showed a higher proportion of morulas vs. the number of blastocysts collected on the wash day. The diameter of the follicles was affected by the administration of different doses of hMG, showing a greater follicular diameter in the groups with higher doses of hMG vs. the lowest dose group. No significant differences were evident in the vaginal membrane opening; as well as ovarian volume, size of corpora lutea and number of follicles. The results obtained suggest that the application of hMG has a direct effect on the ovarian response and therefore on the number of embryos recovered. This response is due to the high number of corpora lutea observed on the day of collection, however, this effect is dose independent.

Characterisation of the cervical mucus was carried out on 19 post-weaning sows until the manifestation of oestrus. Oestrus detection was carried out by means of the immobility reflex, observing the onset of oestrus from the third post – weaning day and reaching its maximum peak on the fifth day. A significant relationship was found between vulvar temperature and the presence of oestrus, as an increase in temperature was observed between days four and five (38.3 ± 0.10°C). Initially, increased cervical mucus was observed in the sows as they approached the day of oestrus. As for pH, it was acidic 24 hours post – weaning (6.7 ± 0.18 pH), increasing progressively to an alkaline state during oestrus (7.5 ± 0.11 pH). With regard to the evaluation of electrical impedance, a reduction in its values was observed from the third post – weaning day (311.3 ± 9.15 ohm), reaching its lowest point on the fifth day, coinciding with the manifestation of oestrus. On the other hand, the elasticity of the cervical mucus changed significantly, starting to increase from the third day, maintaining this tendency until the fifth day of oestrus. In relation to the arborisation of the cervical mucus, positive and highly positive characteristics were evident in the smears on days 4 and 5 respectively. Therefore, the back pressure test can be used with high effectiveness to determine oestrus in sows.

This investigation determined the relationship between the concentration of anti-müllerian hormone (AMH) and the antral follicle count (ARF) in 80 crossbred Holstein cows. The recovered ovaries were transferred to the laboratory to determine the weight, size, and present structures on the ovarian surface (corpus luteum and follicles). In general AMH in plasma (pg/mL) had a mean (± standard deviation), minimum and maximum concentration of 280.1 ± 15.5; 353.7 and 580.1 respectively. The general average of the visual RFA was 26.9 ± 9.49 follicles, and with ultrasound, it was 20.5 ± 7.53 follicles. The cows were classified into three groups based on the number of RFA (High, Medium, and Low); Using the visual technique the average (36.9 ± 1.16) follicles were determine in the High group; Medium (23.8 ± 0.62) and Low (11.4 ± 1.13) groups with the statistical difference between groups (p<0.05); and with ultrasound, it was found, in the High group (31.4 ± 0.26 follicles); the Medium group (19.0 ± 0.41, follicles) and the Low group (10.1 ± 0.69). The size of the right ovary (LE) and left ovary (RE) determined by the two techniques (visual and ultrasound) were similar (29.08 ± 0.51 mm and 30.03 ± 0.57 mm, p˃0 .05). The average weight of both the RE and the LE was (8.18 ± 0.20 g); the weight of the corpus luteum was around 4.12 ± 0.19 g. In conclusion, the AMH concentration positively and significantly correlated with the RFA.

The ovarian response of guinea pigs (Cavia porcellus) was evaluated by applying a superovulation protocol through a recombinant follicle-stimulating hormone (rFSH). 18 multiparous females were selected from ages of 80±15 days, weights from 800g and 1150 g, which had an alimentary adaption process of 15 days with concentrate. Before the superovulation, females were synchronized with progesterone (P4) (Altrenogest®, 0.22mg/kg) orally for 15 days. Before the end of the administration of P4 females were randomly divided into three groups: group 1 (A-rFSH) received a total dose of 30 IU of rFSH (Gonal-F®) twice a day before the withdrawal of P4; group 2 (D-rFSH) received the same dose after the withdrawal of P4; and group 3 (control) did not receive any dose. Administration of rFSH before and after the withdrawal of P4 did not change the number of structures collected in guinea pigs. Likewise, the administration of FSH after the withdrawal of P4 causes females to enter into heat season in a shorter time (D-rFSH 11,15±2,3; A-rFSH 45,15±2,8; C 44,5±4,1, p<0,0001). Like the administration of rFSH, it causes a lower ovarian volume (A-rFSH 39,8±10,2; D-rFSH 29,6±8,1 vs. C 75,8±44,5, p <0,01). In conclusion, superovulation with rFSH before and after the withdrawal P4 does not cause an effect on the ovarian response of guinea pigs and consequently on the number, type and quality of recovered structures. However, guinea pigs show modified ovarian morphology characteristics, suggesting that rFSH treatment may alter morphology characteristics, but not ovarian superovulation response in guinea pigs.

In Mexico, reproductive performance in beef cows is low and the use of synchronization of estrus and ovulation may help to improve it, thus the objective of this review was to describe the endocrine regulation the oestrus cycle and follicular dynamics in cattle, highlighting how these processes can be manipulated by using exogenous hormones. Moreover, wealsopresent some data of pregnancy per artificialinsemination (P/AI) with the different protocols of synchronization of estrus and ovulation reported in theliterature. Reviews and original articles on the estrus cycle and follicular dynamics in cattle were compiled and PRSE data were obtained from papers published from 2000 to 2023. The range of P/AIwas from of 23 to 76%, however despite this wide range, in treatments based on estradiol and GnRH around of 50% of the data of P/AIarebetween 45 and 55%. In progestin-based protocols, 50% of the P/AIobservations were between 55 and 65%. Currently, there are three main protocols for synchronizing oestrus and ovulationthat can be used,agree with therevised literature herein,to obtain P/AI between45 and 65% in most cases with these protocols, En México, la eficiencia reproductiva de las vacas en los sistemas de producción de becerro es bajay el uso de esquemas de sincronización del estro y la ovulación puede contribuir a mejorarla. El objetivo de esta revisión fue describir la regulación endocrina del ciclo estral y la dinámica folicular en los bovinos, resaltando cómo,a través del uso de hormonas exógenas se pueden manipular estos procesospara implementar los diferentes protocolos de sincronización del estro y la ovulación. Además, se presentan resultados de tasa de preñez a estro sincronizado (TPES) con los diferentes protocolos de sincronización de estro y ovulación que se reportan en la bibliografía. Se recopilaron revisiones y artículos originales sobre temas de ciclo estral y desarrollo folicular en bovinos y se obtuvieron datos de TPES de artículos científicos publicados entre 2000 y 2023. La TPES reportada oscila entre 23 hasta 76%, sin embargo, aunque el rango es amplio, en protocolos basados en estradiol y GnRH alrededor del 50% de los datos de TPES colectados están entre 45 y 55%. En protocolos basados en progesterona el 50% de los datos reportan TPES de entre 55 y 65%.En la actualidad, existen tres principales protocolos de sincronización de estro y ovulación con los que, según la bibliografía revisada, se puede obtener TPES de entre 45 y 65% en la mayoría de las ocasiones

The objective of this research was to evaluate the ovarian and hormonal characteristics of the guinea pig after heat synchronization with oral progesterone. The study was carried out in the Biotechnology laboratory of the Faculty of Agricultural Sciences of the University of Cuenca. Forty-three guinea pigs between 4 and 5 months of age were used, with an average weight of 886,2 ± 12,80 grams, they were synchronized for 15 days with oral progesterone (P4) (Altrenogest) for the subsequent assessment of the vaginal membrane, cytology, blood sampling, evaluation of ovarian morphology, antral follicle count and corpus luteum, as well as the classification of COC's obtained at five moments of the estrous cycle day (15, 1, 4, 8 and 11). The results showed that the oral administration of P4 at a dose of 0.22 mg/kg of body weight for 15 days allowed 94.1% of guinea pigs to present vaginal membrane opening (AMV). A mean of 30.1 antral follicles of different sizes available for aspiration was determined, that is, 15.1 follicles/ovary. Collecting 1,249 suitable COC's through the follicular aspiration technique, of which 61.5% come from follicles between (0.5-1 mm), 60% (less than 0.5 mm) and 71.4% (greater than 1 mm). In conclusion, it is confirmed that the follicular dynamics in the guinea pig is biphasic, in addition, the corpus luteum has a growth, static and regression phase and that the preovulatory follicle measures between 0.5-1 mm and that this class of follicles are the ones that provide COC's of the highest quality.

The morphological and functional characteristics of guinea pig oocytes were studied according to the type of COC and stage of the estrous cycle. Forty guinea pigs, synchronized with oral progesterone (Regumate®) for 15 days, were used. Ovaries were collected at periovulatory (day 2) and diestrous (day 9) post-synchronization stage, and 100% of COCs were categorized by morphology into A, B and C. Mitochondrial distribution (MD), nuclear status, oocyte diameter and zona pellucida (ZP) thickness were determined, and in 50% of these, Brilliant Cresyl Blue (BCB) staining was applied. A total of 1053 COCs were obtained (49.9% periovulatory and 50.1% diestrous). From these, 23% were A, 47.5% B and 29.5% C. It was determined that in the periovulatory stage there was a greater percentage of BCB+, while in the diestrous stage a greater percentage of BCB- was obtained. In both the periovulatory and diestrous stage, diffuse DM had a greater percentage with statistical significance. There was a greater proportion of immature oocytes followed by degenerate and the mature oocytes in both stages of the estrous cycle. Oocytes in diestrous were larger in diameter than oocytes in periovulatory (p=0.0126), while the zona pellucida was thicker in periovulatory than in diestrous (p<0.0001). In conclusion, the application of non-invasive methods in guinea pig oocytes to identify characteristics of quality, development, maturation and morphometry were effective.

In the present study, the effect of superovulation with porcine follicle stimulating hormone (pFSH), at different times of cycle on the ovarian response of previously synchronized guinea pigs was determinated. 20 multiparous females were used, wich underwent a synchronization protocol with progesterone (P4) (Altrenogest; 0.22 mg/kg) orally for 15 days. Likewise, 3 groups were formed: group 1 (n=7), where a daily dose of 30 IU of pFSH was applied, divided into two applications, (morning and afternoon), on days 13, 14 and 15 (day of P4 withdrawal); group 2 (n=7), similar to the previous group, was administered the same dose of pFSH twice a day on days 15, 16 and 17; and group 3 (n=6) did not receive a dose, so it was considered as control. The following parameters were then evaluated: hours elapsed from the removal of P4 to the opening of the vaginal membrane (AMV-P4), hours elapsed from the application of pFSH to the opening of the membrane (AMV-pFSH), ovarian volume (VO), total follicles (FOLs), follicular diameter (D-FOLs), total corpora lutea (CLs) and diameter of CLs (D-CLs). As results, it was obtained that the application of pFSH before or after the synchronization with P4 did not influence the ovarian response and thus, morphological changes were observed in the ovary where the VO together with D-FOLs were higher for the pFSH groups; however, in relation to FOLs, CLs and D-CLs, they were not affected.

Ovarian response was evaluated in guinea pigs (Cavia porcellus) presynchronized for 15 days with progesterone prior to the superovulation protocol with different doses of equine chorionic gonadotropin (eCG): 100 IU and 150 IU, applied 24 hours before and at the time (0 hours) of progesterone suppression. Twenty-six multiparous guinea pigs, 100 ± 5 days old, weighing between 800 to 1150 grams were randomly assigned to 5 groups: 100 IU A, 150 IU A, 100 IU D, 150 IU D and control. The number, type and quality of structures were not affected by administering eCG, but it did induce changes on ovarian characteristics; the groups treated with eCG presented greater ovarian volume (100 IU A 77.3±22.9; 150 IU A 52.2±19; 100 IU D 88.2±60.4; 150 IU D 71.1±44.4 mm3 vs. control 21.7± 5.28 mm3), higher number of follicles (100 IU A 10±8; 100 IU D 10.4±9; 150 IU D 15.8±7.2) and larger follicular diameter (100 IU A 0.8±0.5; 150 IU A 1.2±0.7; 100 IU D 0.5±0.3; 150 IU D 0.4±0.2). Whereas, the diameter of the corpora lutea of 150 IU A and 150 IU D was smaller (150 IU A 0.4±0.4 and 150 IU D 0.4±0.4 vs 100 IU A 0.7±0.2 and 100 IU D 0.9±0.1). Also, application of eCG promotes follicular luteinization. In conclusion, administering eCG before or on the day of progesterone suppression does not affect the number, type and quality of recovered structures, but it does have an effect on the morphological characteristics of the ovary.

The objective of this study was to evaluate a superovulation protocol with the purpose of creating an embryo bank for the genetic improvement of the existing sheep flock at the “Nero” experimental farm. To meet this objective, 10 female sheep of the corriedale and katahdin breed and 2 male breeders of the dorper and katahdin breeds were used; the animals had a body condition of 3 ± 0,5; an average age of 3,5 ± 1 years; and an average weight of 60 ± 10 kg. The superovulation protocol employed was: day 0 intravaginal sponge application with 200 mg of medroxyprogesterone acetate (MAP), day 4 sponge replacement; days 8 to 11 administration of FSH in decreasing doses, equivalent to a total of 200 mg; day 10 the sponge was removed and 25 mg prostaglandin F2 alpha was applied; day 12 mating with 3 mating/day every 6 h. At 6 days after 6 days the last mating, retrograde lavage by exploratory laparotomy of the uterine horns was performed. As a result, 50 % (5/10) of the ewes responded to the superovulation protocol recovering the following structures: morulae= 31, blastocysts= 7, unfertilized oocytes= 3. A total of 71 CL (9.91 ± 2.04 mm) and 9 follicles (3.88 ± 0.33 mm) were recorded. There was also a positive correlation (r=0.413, P <=0.0001) between corpus luteum size and embryo quality. In conclusion, the response of the superovulation protocol allowed obtaining a total of 37 freezable and transferable embryos.