Abstract The impact of GnRH treatment on the day of TAI in beef cows has received limited investigation, especially concerning its association with estrus expression. Consequently, two experiments were conducted to assess the potential of GnRH treatment on the day of TAI to enhance fertility according to the expression or not of estrus in beef cows. Experiment 1 aimed to determine ovulation rate and luteal function, while Experiment 2 aimed to determine the effect of the two GnRH treatment approaches on pregnancy rate. In Experiment 1, multiparous Brangus suckling cows (n = 17) were submitted to an 8-day TAI protocol. Estrus occurrence was evaluated based on chalk removal on D10 (TAI) and cows were assigned to receive GnRH (25µg lecirelin; im) according to the group: GnRH (n = 7), regardless of estrus expression; or selectGnRH (n = 10), only cows not detected in estrus. Ovulation rate occurring until 77h after IVD removal did not differ (p = 0.17) between GnRH (85.7%; 6/7) and selectGnRH (100%; 10/10). Also, corpus luteum size and serum progesterone concentration were not affected (p>0.05) by treatments. In Experiment 2, crossbred taurine suckled cows (n = 384) were submitted to the same protocol as described in Experiment 1 and were randomly allocated to GnRH or selectGnRH groups. There was no difference in P/AI between groups (selectGnRH = 55.6%; GnRH = 54.3%; p = 0.7) 30 days after TAI. As expected, there was a pronounced effect (p<0.0001) of estrus expression on P/AI (Estrus = 61.5%; No estrus = 33.0%), regardless of group. In summary, ovulation timing and rate and luteal function did not differ between groups. Also, GnRH administration only in cows that do not show estrus is recommended, considering hormone savings and similar conception rate. investigation Consequently n 17 8day 8 D D1 (TAI 25µg µg lecirelin im group 7, 7 , 7) 10, 10 10) h 0.17 017 0 85.7% 857 85 (85.7% 6/7 67 6 100% 100 (100% 10/10. 1010 10/10 . 10/10) Also p>0.05 p005 05 (p>0.05 treatments 384 PAI P AI 55.6% 556 55 54.3% 543 54 3 0.7 07 expected p<0.0001 p00001 0001 (p<0.0001 61.5% 615 61 5 33.0%, 330 33.0% 33 33.0%) summary recommended 0.1 01 85.7 (85.7 6/ (100 101 10/1 p>0.0 p00 (p>0.0 38 55.6 54.3 0. p<0.000 p0000 000 (p<0.000 61.5 33.0 85. (85. (10 10/ p>0. p0 (p>0. 55. 54. p<0.00 p000 00 (p<0.00 61. 33. (85 (1 p>0 (p>0 p<0.0 (p<0.0 (8 ( p> (p> p<0. (p<0. p<0 (p<0 p< (p<

ABSTRACT. The objective of this study was to evaluate the effect of palm kernel cake and ram effect on reproductive activity of postpartum and lactating ewes. Twenty multiparous ewes, five to eleven days postpartum, were separated into four different treatments: control, control-ram, palm and palm-ram. Body weight, difference in body weight recorded between days 0 and 42 of the experiment, diameter of the largest follicle at day zero of the study, number of ewes bearing a corpus luteum and pregnancy rate were measured in ewes. Average daily weight gain was measured in lambs. There was no effect (p ≥ 0.05) of palm kernel supplementation, ram stimulation, or their interactions on the weights of ewes and lambs. A greater number of ewes with corpus luteum (p < 0.05) were observed in ewes stimulated by rams than those not stimulated. The number of pregnant ewes was not affected by ram effect or palm kernel supplementation (p ≥ 0.05). In conclusion, the use of the ram effect increases the incidence of corpus luteum in postpartum and lactating ewes. In addition, palm kernel cake in the diet does not affect body weight of postpartum ewes and lambs. ABSTRACT treatments control controlram, controlram ram, control-ram palmram. palmram ram. palm-ram 4 experiment lambs p 0.05 005 05 stimulation 0.05. . conclusion addition 0.0 00 0.

Abstract We hypothesized that the hCG modulates the expression of IFNT-pathway and ISGs in bovine endometrium during early pregnancy. The aim of the current study is to evaluate the effect of hCG on IFNT-pathway signals and ISGs expression in endometrial cells. For this, 29 non-lactating cross-bread cows were used in the study and submitted to a 9-day fixed-time artificial insemination (FTAI) protocol. The day of the AI was considered Day 0 (D0), and five days (D5) after the FTAI, the cows were allocated into two groups: Control and hCG group, when a hCG group received a single dose of 2.500UI of hCG. On day 18 after FTAI (D18) cows were slaughtered and endometrial tissue samples were collected. There was no difference between the embryo recovery rate of the cows in C compared to the hCG. The hCG group increased the accessory corpus luteum formation rate. The hCG resulted in greater serum progesterone concentration in the hCG group compared to the C on Day 14. Only the expression of IFNAR2 and STAT1 were upregulated on pregnant cows of the hCG group compared to the C group. The pathway genes (JAK1, STAT2, and IRF9) were not regulated. The mRNA abundance of ISG15, MX1, MX2, and OAS1 was upregulated in pregnant cows for hCG group, compared to C group. The results show that the administration of hCG, 5 days after AI, in addition to increasing the serum progesterone, modulates the expression of IFNT-pathway and ISGs on bovine endometrium on Day 18 of pregnancy. IFNTpathway IFNT pregnancy cells this 2 nonlactating non lactating crossbread cross bread 9day 9 fixedtime fixed time (FTAI protocol D0, D0 D , (D0) D5 (D5 groups 2500UI UI 500UI 1 D18 (D18 collected 14 IFNAR STAT JAK1, JAK1 JAK (JAK1 STAT2 IRF9 IRF regulated ISG15 ISG MX1 MX MX2 OAS (D0 (D D1 (D1 (JAK ISG1

Abstract Follicular dynamics in dairy sheep is poorly understood. This study assessed the follicular dynamics of dairy sheep within and out of the breeding season by observing the effect of two progesterone concentrations (60 and 120 mg) used in vaginal pessaries in pre-synchronization. The experiment was conducted in April/May and October/November using 40 healthy multiparous dairy ewes predominantly of the Lacaune breed, which underwent daily transrectal ultrasound examinations. The number of ovulations (1.35 vs 1.05), ovulatory follicle diameter (mm) (5.97 vs 5.05), length of the luteal phase (11 vs 9.14 days), and length of the estrous cycle (16.83 vs 16.6 days) were assessed within and out of the breeding season, respectively. The sheep out of the breeding season did not present a corpus luteum at the time of insertion of the vaginal pessary, characterizing anestrus. The ovulatory follicle had a larger diameter in the breeding season even with the shorter length of the follicular phase, suggesting higher viability and quality of the ovulated oocyte. The application of exogenous progesterone extends the luteal phase in the breeding season (11 vs 9.14 days). The anestrus observed out of season suggests the need for a higher progesterone concentration in reproductive protocols. Therefore, breeding protocols can be adapted for different seasons, suggesting the use of vaginal pessaries with a higher progesterone concentration (120 mg) out of the breeding season. The data allowed the characterization of follicular dynamics in dairy sheep, demonstrating their differences in each season based on the use of different progesterone doses in pre-synchronization. understood 60 (6 12 mg presynchronization. presynchronization pre synchronization. synchronization pre-synchronization AprilMay April May OctoberNovember October November 4 breed examinations 1.35 135 1 35 (1.3 1.05, 105 1.05 , 05 1.05) mm (mm 5.97 597 5 97 (5.9 5.05, 505 5.05 5.05) 11 (1 914 9 14 9.1 days, days 16.83 1683 16 83 (16.8 166 6 16. respectively pessary oocyte days. . Therefore seasons (12 ( 1.3 13 3 (1. 10 1.0 0 5.9 59 (5. 50 5.0 91 9. 16.8 168 8 (16. 1. 5. (5 (16

Resumo A dinâmica folicular em ovelhas leiteiras é pouco compreendida. Neste trabalho foi avaliado a dinâmica folicular de ovelhas leiteiras, dentro e fora da estação reprodutiva observando o efeito de duas concentrações de progesterona (60 e 120mg) utilizadas em pessários vaginais na pré-sincronização. O experimento foi realizado nos meses de abril/maio e outubro/novembro, utilizando 40 ovelhas multíparas leiteiras hígidas, predominantemente da raça Lacaune, que foram submetidas a exames ultrassonográficos diários por via transretal. Na estação reprodutiva foram avaliados o número de ovulações (1,35 vs 1,05), o diâmetro(mm) do folículo ovulatório (5,97 vs 5,05), a duração da fase lútea (11 vs 9,14 dias) e a duração do ciclo estral (16,83 vs 16,6 dias) dentro da estação em comparação com fora da estação reprodutiva respectivamente. Fora da estação as ovelhas não apresentaram corpo lúteo no momento da inserção do pessário vaginal, caracterizando anestro. Mesmo com menor duração da fase folicular, o folículo ovulatório apresentou maior diâmetro na estação reprodutiva, sugerindo maior viabilidade e qualidade do oócito ovulado. A aplicação de progesterona exógena amplia a fase lútea na estação reprodutiva (11 vs 9,14 dias). O anestro observado fora de época sugere a necessidade de maior concentração de progesterona nos protocolos reprodutivos. Desta forma, é possível adaptar protocolos reprodutivos para diferentes épocas, sugerindo o uso de pessários vaginais com maior concentração de progesterona (120 mg) fora da estação reprodutiva. Os dados obtidos permitiram caracterizar a dinâmica folicular em ovelhas leiteiras, demonstrando suas diferenças em cada estação a partir do uso de diferentes doses de progesterona na pré-sincronização compreendida 60 (6 120mg mg présincronização. présincronização pré sincronização. sincronização abrilmaio abril maio outubronovembro outubro novembro outubro/novembro 4 hígidas Lacaune transretal 1,35 135 1 35 (1,3 1,05, 105 1,05 , 05 1,05) diâmetromm mm diâmetro(mm 5,97 597 5 97 (5,9 5,05, 505 5,05 5,05) 11 (1 914 9 14 9,1 dias 16,83 1683 16 83 (16,8 166 6 16, respectivamente vaginal ovulado dias. . forma épocas 120 (12 ( 1,3 13 3 (1, 10 1,0 0 5,9 59 (5, 50 5,0 91 9, 16,8 168 8 (16, 12 1, 5, (5 (16

Abstract The study aimed to evaluate the effectiveness of combining two injectable progesterone (iP4) formulas for estrous synchronization in ewes and to compare it with traditional intravaginal progesterone devices. Additionally, the study assessed whether the inclusion of GnRH enhances the reproductive outcomes of the iP4 treatment. Two experiments were conducted. In the first experiment, 20 Santa Inês ewes were divided into two groups: one group received intravaginal progesterone devices, and the other received combined long-acting and short-acting iP4. In the second experiment, 30 Corriedale ewes were divided into two groups: one received the combined iP4 with GnRH, and the other without GnRH. Estrous, ovulation, follicular populations, and progesterone concentrations were monitored. The combined iP4 treatment induced an artificial luteal phase and produced reproductive responses similar to those obtained with intravaginal devices. In the first experiment, the iP4 treatment tended to result in more synchronized ovulation compared to the control (P=0.095). In the second experiment, adding GnRH enhanced the quality of the corpus luteum, as indicated by increased diameter and vascularization on Day 23 (P=0.047 and P=0.02, respectively). The combined administration of long-acting and short-acting iP4 effectively synchronized estrous in ewes and showed similar efficacy to traditional intravaginal devices. The inclusion of GnRH improved luteal quality, suggesting potential benefits for reproductive management in ewes. Further studies are needed to evaluate the fertility outcomes of these protocols under field conditions. iP (iP4 devices Additionally conducted experiment 2 groups longacting long acting shortacting short 3 Estrous populations monitored P=0.095. P0095 P P=0.095 . 0 095 (P=0.095) luteum P=0.047 P0047 047 (P=0.04 P002 02 P=0.02 respectively. respectively respectively) conditions (iP P009 P=0.09 09 (P=0.095 P=0.04 P004 04 (P=0.0 P00 P=0.0 (P=0.09 (P=0. P0 P=0. (P=0 P=0 (P= P= (P

Abstract The productivity of the beef and dairy industries depends directly on the reproductive efficiency and genetic gain of the herd, which are directly associated with the appropriate use of Assisted Reproductive Technologies (ARTs). The objective of this review is to show from a Brazilian perspective the evolution over the last 40 years of ARTs related to ovulation resynchronization programs and embryo transfer in cattle. Despite significant improvements and high fertility obtained in timed artificial insemination (TAI) protocols (Sales et al., 2024 - Part I), the improvement of the use of in vitro-produced embryos, development of resynchronization programs, and the advance in Doppler ultrasonography (Doppler-US) for reproductive assessments of bovine females were the ARTs that presented the greatest relevance on reproductive effectiveness in cattle. In the last seven years, the embryo transfer (ET) technology using in vitro-produced (IVP) embryos took over the conventional ET of in vivo produced embryos after donor’s superovulation. Also, procedures and pregnancy rates after ET of IVP embryos were improved in dairy and beef operations. The Doppler-US allows the identification of non-pregnant females at an early stage based on the evaluation of blood perfusion of the corpus luteum. Recent studies in beef and dairy cows indicate satisfactory accuracy when Doppler-US is used at 20-22 days after TAI. Consequently, super-early resynchronization programs have been developed and are being implemented in commercial programs, thereby facilitating earlier conception through the use of semen from superior bulls, providing genetic and economic improvements in herds. Likewise, the assessment of luteal function by Doppler-US allows the selection of embryo recipients with greater receptivity, and consequently may increase the effectiveness of timed ET programs. herd ARTs. . (ARTs) 4 cattle TAI (TAI Sales al al. 202 I, I , I) vitroproduced vitro DopplerUS US (Doppler-US (ET (IVP donors donor s superovulation Also operations nonpregnant non pregnant luteum 2022 20 22 20-2 Consequently superearly super bulls herds Likewise receptivity (ARTs 2 20-

Abstract This review elucidates the physiological and endocrinological processes intrinsic to puberty and ovulation induction protocols in Bos indicus and Bos taurus beef heifers. Puberty is a complex physiological event involving gonadotropic and metabolic changes that lead to sexual maturity, first ovulation, and regular reproductive cycles, enabling females to reproduce. Exposure to progesterone-based hormonal protocols, with or without additional hormones, can reduce the age at first ovulation and improve sexual maturity through stimuli in the hypothalamus-pituitary-gonadal (HPG) axis and uterine development. However, inducing puberty differs from inducing ovulation, as it does not ensure the heifer will continue cycling or be ready to establish and maintain pregnancy after hormonal exposure. Regardless of the pharmacological basis, studies consistently report that beef heifers that had a corpus luteum (CL) prior to the timed-artificial insemination (TAI) protocol, have greater expression of estrus in response to synchronization and greater pregnancy per AI compared to heifers without a CL. The combination of P4 and E2 significantly impacts uterine development, increasing reproductive efficiency. Exposure to P4 causes a positive effect on inducing ovulation. However, studies indicate that the addition of E2 esters at the time of P4 device removal increases the ovulation rate. In general, the studies showed that fertility varied according to the type of the ovulation induction protocol used, but with inconsistent results. Although ovulation induction protocols are strategic tools to accelerate sexual maturity, a holistic view of the entire system is extremely important, combining integration with genetics and nutrition to enhance the reproductive outcomes of beef heifers. Future research is needed to understand and refine these protocols, driving the efficiency of beef cattle production systems. cycles reproduce progesteronebased progesterone based hormones hypothalamuspituitarygonadal hypothalamus pituitary gonadal HPG (HPG development However exposure basis CL (CL timedartificial timed artificial TAI (TAI P E rate general used results important systems

Abstract Pregnancy losses negatively affect the cattle industry, impacting economic indices and consequently the entire production chain. Early embryonic failure has been an important challenge in the embryo industry because proper identification of embryo death at the beginning of gestation is difficult. This review aimed to provide a better understanding on reproductive failure and the relationship between early embryonic loss and different reproductive biotechniques. This review also considers insights and possible strategies for reducing early embryonic loss. The strategies addressed are as follows: i) great impact of rigorous embryo evaluation on reducing embryo losses; ii) selection of recipients at the time of transfer, taking into account health and nutritional status, and classification of the corpus luteum using ultrasound, either in area or vascularization; and iii) paternal effect as one of the factors that contribute to pregnancy losses, with a focus on embryo transfer. chain difficult biotechniques follows i ii transfer status ultrasound vascularization iii

Resumo O objetivo do estudo foi validar a metodologia da imunoquimioluminescência (CLIA) através da imunoabsorção enzimática (ELISA), determinando a concentração sérica de progesterona em vacas de leite e de corte, durante o ciclo estral. Foram empregadas 30 vacas multíparas não-prenhes (12 da raça Holandesa Preta e Branca e 18 Nelore). Vacas com corpo luteo foram escolhidas com vistas à sincronização do estro e da ovulação, mediante aplicação de 500 mcg de cloprostenol (im). Após a aplicação do luteolitico, os animais foram diariamente submetidos a exames de ultrasssonagrafia (US) ovariana para verificação da ovulação (=dia 01 do ciclo), bem como eram colhidas 02 amostras de sangue para a determinação da P4 pela CLIA e ELISA. As amostras eram centrifugadas para a obtenção do soro, e congeladas a -20 graus para posterior dosagem. Os valores de ELISA e CLIA foram comparados entre si mediante teste t pareado, regressão, ANOVA e coefficiente de determinação (R2), visando a verificação da sensibilidade e correspondência linear. A concentração de P4 originou perfis similares entre as duas metodologias; os perfis de P4 foram mais elevados em bovinos de corte, que nos de leite. A correspondência entre as metodologias resultou em elevado quociente de R2 nos perfis de P4. Concluiu-se que a CLIA pode ser empregada nas determinações hormonais da P4 serica bovina; a CLIA mostrou elevada correspondência linear com os valores da ELISA; a CLIA pode auxiliar as biotecnicas da reprodução nas determinações hormonais. (CLIA ELISA, , (ELISA) corte estral 3 nãoprenhes não prenhes 12 (1 1 Nelore. Nelore . Nelore) 50 im. im (im) luteolitico US (US =dia dia 0 ciclo, ciclo) P soro 20 -2 dosagem pareado regressão R2, R (R2) Concluiuse Concluiu se bovina (ELISA ( 5 (im 2 - (R2 (R

Abstract This study aimed to validate the methodology of immunochemiluminescence (CLIA) using an enzyme-linked immunosorbent assay (ELISA) to determine serum progesterone (P4) concentrations in non-pregnant multiparous dairy (12 Holstein cows) and beef (18 Nellore cows) cows during the estrous cycle. Cows with corpus luteum were chosen for estrus and ovulation synchronization by administering 500 mcg of cloprostenol. After luteolytic application, the animals were subjected to ovarian ultrasonography (US) daily to verify ovulation (day zero of the cycle) and two blood samples were collected for P4 determination using CLIA and ELISA. Samples were centrifuged to obtain serum and frozen at -20 °C for later measurement. ELISA and CLIA values were compared using the paired t-test, regression, analysis of variance, and coefficient of determination (R2) to verify sensitivity and linear correspondence. The P4 concentration determined by both methodologies showed a similar profile; the P4 profiles were higher in beef cattle than in dairy cattle. The correspondence between the methodologies resulted in a high quotient for R2 the P4 profiles. It was concluded that CLIA can be used for hormonal determinations of bovine serum P4. CLIA showed a high linear correspondence with ELISA values and can thus aid reproductive biotechnologies for hormone determination. (CLIA enzymelinked enzyme linked (ELISA P (P4 nonpregnant non pregnant 12 (1 18 cycle 50 cloprostenol application US (US day 20 -2 C measurement ttest, ttest t test, test t-test regression variance R (R2 profile (P 1 ( 5 2 - (R

Abstract The aim was to examine the exogenous supply of progesterone, and the influence of the corpus luteum (CL) at the beginning of the estrus synchronization protocols in sheep, for 6 and 11 days, on reproductive variables. The sheep were presynchronized to obtain a premature or functional CL at the beginning of the synchronization period to be evaluated. Estrus presentation was lower in short treatments; This triggered a difference (p < 0.05) in pregnancy rate between short and conventional treatments. On the day of estrus, steroid concentration was different: progesterone was higher in short treatments; while estradiol was lower in the short treatment with CL. The presence of a premature or functional CL at the initiation of the treatments commonly used to synchronize estrus does not modify the expression of the reproductive variables; Nevertheless, in short treatments the expression is affected. It is important to use ultrasonography to corroborate what happened at the ovarian level.

Resumen El objetivo fue evaluar el aporte exógeno de progesterona, y la influencia del cuerpo lúteo (CL) al iniciar protocolos de sincronización de estros en ovejas, por 6 y 11 días, sobre las variables reproductivas. Las ovejas fueron presincronizadas para obtener un CL inmaduro o funcional al iniciar el periodo de sincronización a evaluar. La presentación de estros fue baja en tratamientos cortos; esto desencadenó discrepancias (p < 0.05) en porcentaje de gestación de tratamientos de 6 días y los tradicionales de 11 días. El día del estro la concentración de esteroides fue diferente, progesterona fue mayor en tratamientos cortos; mientras que estradiol fue menor en el tratamiento corto con CL. La presencia de un CL inmaduro o funcional al iniciar tratamientos para sincronizar estro convencionales no modifica la expresión de las variables reproductivas; sin embargo, en tratamientos cortos la expresión se ve afectada. Es importante el uso de ultrasonografía para corroborar lo que pasa a nivel ovárico.

Abstract Transrectal ultrasonography is a technology used in cattle reproductive management as a means of gestation diagnosis and estrous cycle monitoring. Likewise, it has application in the management, diagnosis and treatment of both reproductive processes and in reproductive biotechnology programs. The objective of the work was to carry out a bibliographic review on the reproductive processes in cows and the ultrasonography use. A bibliographic review was carried out including publications from 2022 and previous years. Criteria that support the development achieved in the use of ultrasound were considered, based on the logical analysis of the consulted bibliography. The keywords used were ultrasonography, ultrasound, cattle, bovine reproduction, transrectal palpation, estrous cycle, follicular dynamics, ovarian function, Doppler, corpus luteum functionality, early pregnancy diagnosis, embryonic death. Transrectal ultrasonography has increased our knowledge and understanding of bovine reproductive physiology. Technological advances have allowed its use in the reproductive management of cattle to increase. Ultrasonography is a revolutionary advance in research that has influenced the efficiency of cow reproductive management.

Resumen La ultrasonografía transrectal es una tecnología utilizada en el manejo reproductivo de los bovinos como medio del diagnóstico de gestación y de seguimiento del ciclo estral. Asimismo, tiene aplicación en el manejo, diagnóstico y tratamiento tanto de procesos reproductivos como en programas de biotecnología reproductiva. El objetivo del trabajo fue realizar una revisión bibliográfica sobre los procesos reproductivos en vacas y el uso de la ultrasonografía. Se realizó una revisión bibliográfica incluyendo publicaciones del 2022 y años previos. Se consideraron criterios que sustentan el desarrollo alcanzado en el uso de ultrasonido, basados en el análisis lógico de la bibliografía consultada. Las palabras clave utilizadas fueron ultrasonografía, ecografía, bovinos, reproducción bovina, palpación transrectal, ciclo estral, dinámica folicular, función ovárica, Doppler, funcionalidad del cuerpo lúteo, diagnóstico precoz de la preñez, muerte embrionaria. La ultrasonografía transrectal ha aumentado nuestro conocimiento y comprensión de la fisiología de la reproducción del bovino. Los avances tecnológicos han permitido que su empleo en el manejo reproductivo del ganado bovino se incremente. La ultrasonografía es un avance revolucionario en la investigación que ha influenciado la eficiencia en el manejo reproductivo de la vaca.

Abstract 27. The objective of this study was to evaluate the effect of two doses of equine chorionic gonadotropin (eCG) in a J-Synch protocol, using 107 cows with calves at foot, Holstein, Brown Swiss, and their crosses, with a body condition (CC) of 2.5 (scale 1-5), and a silvopastoral system. The trial consisted of two treatments (T): T1 = 1 dose of eCG (n=52) and T2 = 2 doses of eCG (n=55). On day 0, an intravaginal device (BID) containing 0.5 g progesterone (P4) and 2 mg estradiol benzoate (BE) was administered. On day 6, the DIB was removed and 500 μg Cloprostenol (PGF2α) + 400 IU of eCG was administered. The base of the tail was painted, to determine estrus manifestation. Unpainted animals were inseminated at 60 h and painted animals at 72 h, + 100 µg of (GnRH). At T1 treatment, the size of the corpus luteum (CL) was measured on days 14 and 30 after insemination, and blood samples were taken. At T2 treatment, a second dose of 400 IU of eCG was administered on day 14, and CL size was measured, as well as on day 30, and blood samples were taken. The pregnancy diagnosis was made 40 days after the IATF, by ultrasonography. The highest pregnancy rate was observed in T2 (58.2%), and in cows in estrus (56.6%). No statistical differences were observed between treatments (p=0.7). Serum P4 concentrations were not different. Similarly, the diameter of the CL at days 14 and 30 post IATF did not differ (p>0.05). However, the size of the CL at days 14 and 30, is clearly related (p<0.001). In conclusion, a second dose of eCG on day 14 in the J - Synch protocol had no effect on pregnancy but a tendency to improve performance in Ecuadorian Amazonian cows.

Resumen 23. El objetivo de este estudio fue evaluar el efecto de dos dosis de gonadotropina coriónica equina (eCG) en el protocolo J-Synch, utilizando 107 vacas con cría al pie, de razas Holstein, Pardo Suizo y sus cruzas, con una condición corporal (CC) de 2,5 (escala 1-5), y un sistema silvo-pastoril. El estudio consistió de dos tratamientos (T): T1 = 1 dosis de eCG (n=52), y T2 = 2 dosis de eCG (n=55). El Día 0 se aplicó un dispositivo intravaginal (DIB) con 0,5 g de progesterona (P4) y 2 mg de benzoato de estradiol (BE). Al día 6, se retiró el DIB y se administraron 500 μg de Cloprostenol (PGF2α) + 400 UI de eCG. Se pintó la base de la cola, para determinar manifestación de estro, inseminando animales despintados a las 60 horas y pintados a las 72 horas, + 100 µg de (GnRH). En el T1 se midió el tamaño de cuerpo lúteo (CL) en los días 14 y 30 después de la inseminación y se tomaron muestras de sangre. En el T2, se administró una segunda dosis de 400 UI de (eCG) al día 14, y se midió el tamaño de CL, al igual en día 30, y se tomaron muestras de sangre. El diagnóstico de gestación se realizó a los 40 días después de la IATF, mediante ultrasonografía. La mayor tasa de preñez fue en el T2 (58,2%), y en vacas en estro (56,6%), sin evidenciar diferencias relevantes (p=0,7). Las concentraciones séricas de P4, no difieren. Asimismo, el diámetro del CL de los días 14 y 30 post IATF (p>0,05). Sin embargo, la magnitud del CL en los días 14 y 30, están claramente relacionados (p<0,001). En conclusión, una segunda dosis de eCG al día 14 en el protocolo J-Synch, no tuvo influencia sobre la preñez, pero si una tendencia a desempeñarse mejor en vacas de la Amazonía Ecuatoriana.

Resumen La transferencia de embriones (TE) es considerada actualmente como una herramienta biotecnológica con gran importancia para multiplicar y obtener individuos con potencialidades productivas y alto mérito genético. El objetivo de este estudio fue determinar la influencia de factores como ITH, tamaño del CL, estado de desarrollo del embrión y peso sobre la tasa de preñez mediante transferencia de embriones por fertilización in vitro en novillas multirraciales. Se seleccionaron 840 novillas como receptoras, con edades promedio de 3 años, un peso de 346.5 ± 33.4 kg de peso vivo, a las cuales se les aplicó un protocolo de sincronización para TE, previo registro del estadio del embrión, seguimiento ecográfico y se realizó el monitoreo de variables medioambientales. La información se analizó mediante un modelo de regresión logística para determinar la correlación entre las variables independientes sobre la variable dicotómica de respuesta tasa de preñez. Se determinó la influencia del tamaño del cuerpo lúteo (CL) dado las diferencias significativas (P<0.05) en los tamaños de CL1 y CL2. También, se encontró diferencias (P<0.05) con los estadios de BL y BX. En contraste, no se encontró diferencias estadísticas (P>0.05) en las demás variables. El presente estudio evidenció el impacto del tamaño del CL y el desarrollo del embrión en el éxito de la técnica de TE.

Abstract Embryo transfer (ET) is currently considered a biotechnological tool with great importance to multiply and obtain individuals with productive potential and high genetic merit. The objective of this study was to determine the influence of factors such as THI, CL size, embryo development status and weight on the rate of pregnancy by embryo transfer by in vitro fertilization in multibreed heifers. Eight hundred forty heifers were selected as recipients, with an average age of 3 years, a weight of 346.5 ± 33.4 kg of live weight, to which a synchronization protocol for ET was applied, after recording the stage of the embryo, ultrasound monitoring and the environmental variables were monitored. The information was analyzed using a logistic regression model to determine the correlation between the independent variables and the dichotomous response variable pregnancy rate. The influence of corpus luteum (CL) size was determined given the significant differences (P<0.05) in the sizes of CL1 and CL2. Differences (P<0.05) were also found with the stages of BL and BX. In contrast, no statistical differences (P>0.05) were found in the other variables. The present study showed the impact of CL size and embryo development on the success of the ET technique.

ABSTRACT. Litter size is one of the crucial factors in livestock production and is of high economic value, which is affected by ovulation rate, hormones, and growth factors. Growth factors play a multifaceted role in reproductive physiology. This review aims to investigate the association of bone morphogenetic protein 15 (BMP15) and growth differentiation factor 9 (GDF9) with litter size in livestock. The transforming growth factor β (TGF- β) superfamily includes more than 34 members; GDF9 and BMP15 are among the most significant factors for regulating fertility and litter size in most livestock species. Ovarian follicles release BMP15 and GDF9 that are involved in the maturation of primary follicles into the basal form, proliferation of granulosa and theca cells, steroidogenesis, ovulation, and formation of the corpus luteum. Besides, these factors are highly expressed in oocytes and are necessary for female fertility and multiple ovulation in several livestock species. Animals with two inactive copies of these factors are sterile, while those with one inactive copy are fertile. Thus, the present review provides valuable information on the association of BMP15 and GDF9 with litter size in livestock that can be used as biological markers of multiple ovulation or for improving fertility in livestock. ABSTRACT value rate hormones physiology 1 BMP (BMP15 GDF (GDF9 TGF (TGF 3 members BMP1 species form cells steroidogenesis luteum Besides sterile fertile Thus (BMP1 (GDF (BMP

Abstract Ovarian torsion can be defined as the bending of the ovaries on the supporting ligament, disrupting both venous and arterial blood circulation. Insufficient blood flow causes ovarian tissue hypoxia and leads to ischemia. This study aimed to investigate whether tocilizumab has a protective effect on ischemia-reperfusion injury due to ovarian torsion in rats. Eighteen female Wistar albino rats were divided into three equal groups (Sham (SG), ischemia-reperfusion (OIR), and ischemia-reperfusion+tocilizumab (OIRT)). Degeneration, necrosis, vascular dilatation/congestion, interstitial edema, hemorrhage, and polymorphonuclear lymphocyte (PMNL) infiltration scores were significantly different between the groups (p=0.001 for all parameters). Moreover, the OIRT group had a significant improvement in these criteria compared to the OIR group (p<0.05). Additionally, there was a considerable difference between OIRT and OIR groups in the number of primordial, developing, and atretic follicles groups (p<0.05), while there was no difference in the number of corpus luteum (p=0.052). Stress markers or cytokines, such as MDA, tGSH, NF-κB, TNF-α, IL-1β, and IL-6, were significantly different between groups (p<0.05). Furthermore, a significant improvement was found in the measured variables when the OIRT group was compared with the OIR group (p<0.05). Tocilizumab may be an alternative option for treating ischemia-reperfusion injury due to ovarian torsion. ligament circulation ischemia ischemiareperfusion reperfusion Sham SG, SG , (SG) OIR, (OIR) ischemiareperfusion+tocilizumab ischemiareperfusiontocilizumab reperfusion+tocilizumab OIRT. . (OIRT)) Degeneration necrosis dilatationcongestion dilatation congestion dilatation/congestion edema hemorrhage PMNL (PMNL p=0.001 p0001 p 0 001 (p=0.00 parameters. parameters parameters) Moreover p<0.05. p005 p<0.05 05 (p<0.05) Additionally primordial developing p<0.05, p=0.052. p0052 p=0.052 052 (p=0.052) cytokines MDA tGSH NFκB, NFκB NF κB, κB NF-κB TNFα, TNFα TNF α, α TNF-α IL1β, IL1β ILβ IL 1β, 1β β IL-1β IL6, IL6 6, 6 IL-6 Furthermore (SG (OIR reperfusiontocilizumab (OIRT) p=0.00 p000 00 (p=0.0 p00 p<0.0 (p<0.05 p=0.05 (p=0.052 IL- (OIRT p=0.0 (p=0. p0 p<0. (p<0.0 (p=0.05 p=0. (p=0 p<0 (p<0. p=0 (p= p< (p<0 p= (p (p<