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Oxidative stress is the result of an imbalance between free radicals and antioxidants. Under normal physiological conditions, free radicals are involved in reproductive events such as cell cycle activation, ovulation and luteolysis. However, when an overproduction of free radicals surpasses antioxidant capacity, oxidative damage, reproductive anomalies and diminished fertility occur. Supplementation with antioxidants prevents oxidative damage and can be incorporated into reproductive management to improve fertility in females. Selection of the preovulatory follicle, ovulation, fertilization, embryo development and formation of the corpus luteum occur during the periconceptional period. This is a dynamic period and the events are susceptible to oxidative stress damage. Therefore, the objective of this review is to discuss the effect of oxidative stress on reproductive events during the periconceptional period, as well as to address antioxidant supplementation during this period., Resumo O stress oxidativo é gerado por um desequilíbrio entre radicais livres e antioxidantes. Sob condições fisiológicas normais, os radicais livres participam de eventos reprodutivos, como ativação do ciclo estral, ovulação e luteólise. No entanto, quando é produzido em quantidades que excedem a capacidade antioxidante do organismo, produzem danos oxidativos e distúrbios reprodutivos que diminuem a fertilidade da fêmea. A suplementação com antioxidantes previne o dano oxidativo e sua incorporação em programas de gerenciamento reprodutivo pode ser uma opção para melhorar a fertilidade da fêmea. A seleção do folículo pré-ovulatório, ovulação, fecundação, desenvolvimento embrionário e formação do corpo lúteo ocorrem durante o período periconcepcional. Este é um período dinâmico e os eventos que ocorrem são suscetíveis ao dano por estresse oxidativo. Portanto, o objetivo dessa revisão é fornecer ao leitor conhecimento sobre o efeito do estresse oxidativo em eventos reprodutivos durante o período periconcepcional, e também discutir a suplementação com antioxidantes em ruminantes durante este período., Resumen El estrés oxidativo es generado por un desbalance entre radicales libres y antioxidantes. Bajo condiciones fisiológicas normales, los radicales libres participan en eventos reproductivos tales como activación del ciclo celular, ovulación y luteólisis. Sin embargo, cuando estos son producidos en cantidades que sobrepasan la capacidad antioxidante del organismo producen daño oxidativo y trastornos reproductivos que disminuyen la fertilidad de la hembra. La suplementación con antioxidantes previene el daño oxidativo y su incorporación a programas de manejo reproductivo puede ser una opción para mejorar la fertilidad de la hembra. La selección del folículo preovulatorio, ovulación, fecundación, desarrollo embrionario y formación del cuerpo lúteo ocurren durante el periodo periconcepcional. Este es un periodo dinámico y los eventos que ocurren en él son susceptibles a daño por estrés oxidativo. Por tanto, el objetivo de esta revisión es discutir el efecto del estrés oxidativo en los eventos reproductivos durante el periodo periconcepcional, así como la suplementación de antioxidantes en rumiantes durante este periodo.

Agribusinesses of dairy cattle in the country are quite heterogeneous, which is why it is necessary to classify them for their analysis and adequate improvement. The objective of this study was to stratify family dairy producers in the Jalisco Highlands that used technological development advice and consulting by CHAPINGO-AGROPEC Star with the methodology proposed by FAO to identify differences in the productive characteristics of dairy agribusinesses within each stratum. The components of the grouping were: Schooling (ES), Equivalent Irrigation Surface (SER), Bovine Equivalent (BE) and Technological Level; the latter was broken down into Indexes of Genetic Quality (ICG), Dietary Management (IMA), Reproductive Management (IMR), Sanitary Management (IMS) and Infrastructure and Equipment (IIE) (all abbreviations for initials in Spanish). Two types of producers were identified: transition (88 %), and entrepreneurial (12 %). The transition producers had an average of 87 BE, basic education, and a SER of 12 ha; 67 % of them carried out artificial insemination (IA) in addition to mounting, and the diet offered to their cattle was quite diverse. The entrepreneurial producers had in average 190 BE, professional education and a SER of six ha, 100 % applied IA, and balanced meals was supplied to the livestock. The stratification of agribusinesses was appropriate and useful., Las agroempresas de bovinos lecheros en el país son muy heterogéneas, por lo que es necesario clasificarlas para su análisis y mejora adecuada. El objetivo del trabajo fue estratificar productores de lechería familiar de Los Altos de Jalisco que utilizaron el desarrollo tecnológico de asesoría y consultoría CHAPINGO-AGROPEC Star con la metodología propuesta por la FAO para identificar diferencias en las características productivas de agroempresas lecheras dentro de cada estrato. Los componentes de agrupación fueron: Escolaridad (ES), Superficie Equivalente de Riego (SER), Bovino Equivalente (BE) y Nivel Tecnológico; este último se desglosó en Índices de Calidad Genética (ICG), Manejo Alimenticio (IMA), Manejo Reproductivo (IMR), Manejo Sanitario (IMS) e Infraestructura y Equipo (IIE). Se identificaron dos tipos de productores: de transición (88 %) y empresariales (12 %). Los productores de transición tuvieron en promedio 87 BE, educación básica, y una SER de 12 ha; 67 % de ellos realizó inseminación artificial (IA) más monta, y la alimentación ofrecida a su ganado fue muy variada. Los empresariales tuvieron en promedio 190 BE, educación profesional y una SER de seis ha, 100 % aplicó IA, y se proporcionó alimento balanceado al ganado. La estratificación de las agroempresas fue apropiada y útil.

La reproducción de los bovinos lecheros se puede afectar por factores relacionados con el manejo. El objetivo del trabajo fue evaluar el comportamiento reproductivo en vacas lecheras de agroempresas con dos niveles tecnológicos (NT): transición y empresarial, que utilizan el desarrollo tecnológico de asesoría y consultoría CHAPINGO-AGROPEC Star®. Se analizó información de 17 agroempresas que incluyeron 2041 vacas y 5922 partos. Las variables fueron: edad al primer parto (EPP), servicios por concepción (SPC), días abiertos (DA), intervalo entre partos (IEP), intervalo al primer celo posparto (IPCP) e intervalo al primer servicio posparto (IPSP). Se consideró un modelo mixto que incluyó los efectos fijos de número (NP), año (AP) y época (EP) de parto, NT y agro-empresa (AE), y las interacciones dobles significativas entre estos efectos. Se obtuvieron diferencias significativas (p£0.05) en NT para los indicadores IPCP e IPSP; la interacción de NT por AP, además de tener efecto en estas dos variables, también influyó en EPP. El NT empresarial presentó IPCP y IPSP (63.8±6.2 y 75.7±5.5 d) menores que el NT de transición (90.8±2.7 y 91.1±2.3 d). El comportamiento reproductivo de las vacas en los dos NT fue similar debido a que no hubo diferencias significativas en EPP, SPC, DA e IEP

Background: recombinant bovine somatotropin (rbST) is used in bovine embryo donors to improve superovulatory response and embryo quality. Objective: this study evaluated the effect of applying one versus two injections of 500 mg of rbST to donor Holstein heifers on estrus incidence (IE), diameter of the largest preovulatory follicle (dLPF), superovulation response (SR), embryo yield, and pregnancy rate in recipient Holstein cows (PRR). Methods: two superstimulation programs were conducted. Heifers were assigned to one of two treatments: 1) rbST-I, n = 5: heifers received one injection of rbST on day 0 (day of CIDR (controlled internal drug release) removal); 2) rbST-II, n = 5: heifers received the first rbST injection on day -8 and the second one on day 0. Thirty-eight cows were used as recipients and were assigned to receive one embryo from one of the two treatments. Results: there was no effect of treatment (p˃0.05) on PRR, dLPF, IE, and SR. The number of oocytes increased (p˂0.05) in the rbST-I treatment (1.3 ± 0.4 vs 0.2 ± 0.2), but there was no difference in the number (p˃0.05) of degenerated (1.0 ± 0.5 vs 4.5 ± 3.0) or transferable (1.0 ± 0.5 vs 1.4 ± 0.7) embryos between heifers in the rbST-I and rbST-II treatments, respectively. Moreover, no oocytes or embryos were recovered from 36.8% of donor heifers in either treatment. Conclusion: the application of 500 mg of rbST on days -8 and 0 of the follicular wave synchronization program did not increase the superovulatory response but significantly reduced the number of oocytes recovered from superovulated Holstein heifers., Antecedentes: a somatotropina bovina recombinante (rbST) tem sido aplicada em vacas doadoras de embriões com o objetivo de melhorar a resposta superovulatória e a qualidade embrionária. Objetivo: o presente trabalho avaliou o efeito da aplicação de uma contra duas injeções de 500 mg de rbST em novilhas de raça Holandesa doadoras de embriões na incidência do cio (IE), diâmetro do maior folículo pré-ovulatorio (dLFP), resposta superovulatória (SR), produção de embriões e taxa de gestação em vacas receptoras de raça Holandesa (PRR). Métodos: foram feitos dois programas de superestimulação, em cada superstimulação as novilhas foram distribuídas em um de dois tratamentos: 1) rbST-I, n = 5: as novilhas receberam uma injeção de rbST no dia zero (dia de remoção do CIDR -dispositivo intravaginal de liberação controlada de progesterona). 2) rbST-II, n = 5: as novilhas receberam a primeira injeção de rbST no dia -8 e a segunda injeção no dia zero. Trinta e oito vacas foram utilizadas como receptoras e receberam um embrião proveniente de uma doadora de um dos dois tratamentos. Resultados: a aplicação de uma ou duas injeções de rbST não afetou (p˃0,05) a PRR, dLFP, IE nem a SR. O número de oócitos foi maior (p˂0,05) no tratamento rbST-I (1,3 ± 0,4 vs 0,2 ± 0,2), o número de embriões não-viáveis (1,0 ± 0,5 vs 4,5 ± 3,0) ou viáveis (1,0 ± 0,5 vs 1,4 ± 0,7) não foram diferentes (p˃0,05) entre as novilhas do tratamento rbST-I e rbST-II. Além disso, do 36.8% das doadoras de ambos os tratamentos não foi possível coletar nenhum oócito ou embrião. Conclusões: A aplicação de 500 mg de rbST o dia -8 e zero do protocolo de sincronização da onda folicular não aumentou a resposta superovulatória, mas diminuiu significativamente o número de oócitos coletados de novilhas de raça Holandesa superovuladas., Antecedentes: la somatotropina bovina recombinante (rbST) ha sido aplicada en vacas donadoras de embriones con el objetivo de mejorar la respuesta superovulatoria y la calidad embrionaria. Objetivo: este trabajo de investigación evaluó el efecto de aplicar una versus dos inyecciones de 500 mg de rbST a novillas Holstein donadoras de embriones sobre la incidencia de celo (IE), diámetro del folículo preovulatorio de mayor tamaño (dLFP), respuesta superovulatoria (SR), producción de embriones y tasa de concepción en vacas Holstein receptoras de embriones (PRR). Métodos: se llevaron a cabo dos programas de superestimulación. En cada programa las novillas fueron asignadas a uno de dos tratamientos: 1) rbST-I, n = 5: las novillas recibieron una inyección de rbST el día cero (día de remoción del CIDR (dispositivo intravaginal liberador de progesterona); 2) rbST-II, n = 5: las novillas recibieron la primera inyección de rbST el día -8 y la segunda el día cero. Treinta y ocho vacas fueron utilizadas como receptoras. Cada receptora recibió un embrión proveniente de una donadora de uno de los dos tratamientos. Resultados: la aplicación de una o dos inyecciones de rbST no afectó (p˃0,05) la PRR, dLFP, IE ni la SR. El número de ovocitos fue mayor (p˂0,05) en el tratamiento rbST-I (1,3 ± 0,4 vs 0,2 ± 0,2), el número de embriones degenerados (1,0 ± 0,5 vs 4,5 ± 3,0) o transferibles (1.0 ± 0,5 vs 1,4 ± 0,7) no fue diferente (p˃0,05) entre las vaquillas del tratamiento rbST-I y rbST-II. Además, del 36,8% de donadoras de ambos tratamientos no se colectó ningún ovocito o embrión. Conclusión: la aplicación de 500 mg de rbST los días -8 y cero del protocolo de sincronización de la onda folicular no incrementó la respuesta superovulatoria pero redujo significativamente el número de ovocitos recolectados de vaquillas Holstein superovuladas.

Three trials using 6-7 month-old Romney ewe lambs and adult ewes were conducted to evaluate the feasibility of implementing a juvenile MOET scheme. Older lambs were used to evaluate ways of improving the ovulation rates in 3 additional trials, one of them involved Booroola-cross lambs. Studies were also carried out to develop and evaluate a technique for splitting sheep embryos, and these were transferred to recipient ewes. In the three trials involving superovulation and transfer a range of gonadotrophin treatments were used. The more highly purified preparations (FSH-P, Ovagen) gave lower responses compared with PMSG (1.78, 1.06 vs 4.18 respectively in Trial 3, P<0.01). Ovulation rate of ewe lambs relative to adult ewes in the 3 trials were respectively 1.20 vs 2.00 (P<0.01), 4.18 vs 6.35 and 1.61 vs 3.15. Overall, administration of GnRH did not significantly increase the ovulation rates, although lambs treated with PMSG + GnRH tended to give higher responses. Egg recovery was higher in most cases in adults than in lambs (91% vs 55%, P<0.01; 72% vs 47%. P<0.01; 34% vs 43%, for trials 1, 2 and 3 respectively). Fertilization rate in trial 1 was lower in lambs than in adults (50% vs 82%, P<0.05) but not different in trials 3 and 5, probably due to the use of intrauterine insemination. Ovulation rate was not improved by treating lambs at 8-9 months of age or by administering PMSG 2 or 4 days before sponge removal. Ovulation rates following gonadotrophin stimulation were higher in androstenedione-immunized ewe lambs than in non-immunized ewe lambs (2.22 vs 1.59. P<0.05). Booroola-cross lambs treated at 6-7 months of age gave considerably higher ovulation rates compared to those recorded in Romney lambs from another experiment conducted at the same time (3.79 vs 1.61). Lower embryo survival and incidence of twins were found for demi-embryos generated from 9-10 month-old lambs compared to those obtained from 24 months or older animals. Higher pregnancy rate and demi-embr

A study was carried out to develop an embryo transfer programme under farm conditions. For this embryos were collected from donor ewes 5-6 days after single-sire mating by rams of the same crossbreed as the ewes. Then the embryos were transplanted soon after collection or after they had been initially frozen and later on thawed before their transfer. To enable this study to be carried out, one hundred and sixty-one Booroola-Merino x Perendale ewes aged between 3 and 6 years and of 34-69 kg live weight were examined. These animals were classified as either carriers (F+) or non-carriers (++) of the fecundity gene on the basis of the number of ovulations recorded at laparoscopy carried out a few days after progestagen sponge treatment to induce oestrus synchronisation, and in a few cases on the basis of previous lambing data. The aims of the study therefore were also to identify ewe carriers or non-carriers of the fecundity gene, and to evaluate their ovulatory response to several doses of Pregnant Mare Serum Gonadotrophin (Tl=O, T2=350, T3=700 and T4=1050 i.u. of PMSG) given during the embryo transfer programme. On the basis of the criteria used to classify F+ and ++ ewes, 76 ewes were considered as carriers and 85 as non-carriers of the fecundity gene. Immediately after progestagen synchronisation treatment the incidence of oestrus and the distribution of onset of oestrus was similar in both groups of ewes, and also following PMSG treatment given in the succeeding cycle. Ovulation rate after the progestagen sponge treatment was significantly affected by genotype and age of the ewes, but it was not associated with the live weight of the ewes. The least-squares means for number of ovulations in F+ and ++ ewes and in 3 and 4-6 years old animals were 3.02, 1.73, 2.14 and 2.45 respectively. Higher sensitivity to PMSG treatment was observed from the right ovary than from the left ovary (3.40 v. 2.82 ovulations respectively). No significant effect of dose of PMSG was found