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Objective: To measure the effect of zin injection, during an estrus synchronization protocol, on pregnancy rate in sheep from the “Valle de Mexicali”.Design/methodology/approach: The experimental units were 157 ewes, which wereallocated in five farms (UP): UP1 (n=19), UP2 (n=27) UP3 (n=20) UP4 (n=71) and UP5(n=21). In each farm, the ewes were randomly assigned to one of three treatments:control, z-100 and z-200. The ewes from control groups were subcutaneously injectedwith 4 mL of olive oil as placebo. The ewes from groups z-100 and z-200 weresubcutaneously injected with 100 and 200 mg of zinc oxide. The response variableswere the preovulatory diameter of the largest follicle and pregnancy rate.Results: The differences between experimental groups on diameter of the largestpreovulatory follicle and pregnancy rates were not significant different (p>0.05). Limitations of the study/implications: The ewe’s reproductive response to zincinjection might be affected by the animal mineral status, it is recommended to carry onsupplementation with base on mineral blood concentrations.Conclusion: The subcutaneous injection with 100 or 200 mg of zinc oxide did not affectthe size of the largest preovulatory follicle and pregnancy rate in ewes.

Ascorbic acid (vitamin C: VC) is an antioxidant that participates in the regulatory processes involved in the development of ovarian structures and fertility. However, supplementation of VC to dairy cattle to improve fertility has received little attention. However, reduced fertility in dairy cattle associated with high genetic merit for milk production and heat stress, which also diminish blood VC concentrations, suggest a potentially beneficial role for VC supplementation. The objectives of this review are to contribute to the current knowledge regarding the relationship between VC and fertility and to share many experiences that support the relevance of VC supplementation to improve dairy cattle reproductive performance.

Summary Background: recombinant bovine somatotropin (rbST) is used in bovine embryo donors to improve superovulatory response and embryo quality. Objectiv e: 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) 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. Keywords: conception rate, donor heifers, incidence of estrus, preovulatory follicle. Resumen 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 investigacion evaluo 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), diametro del foliculo preovulatorio de mayor tamano (dLFP), respuesta superovulatoria (SR), produccion de embriones y tasa de concepcion en vacas Holstein receptoras de embriones (PRR). Metodos : se llevaron a cabo dos programas de superestimulacion. En cada programa las novillas fueron asignadas a uno de dos tratamientos: 1) rbST-I, n = 5: las novillas recibieron una inyeccion de rbST el dia cero (dia de remocion del CIDR (dispositivo intravaginal liberador de progesterona); 2) rbST-II, n = 5: las novillas recibieron la primera inyeccion de rbST el dia -8 y la segunda el dia cero. Treinta y ocho vacas fueron utilizadas como receptoras. Cada receptora recibio un embrion proveniente de una donadora de uno de los dos tratamientos. Resultados : la aplicacion de una o dos inyecciones de rbST no afecto (p > 0,05) la PRR, dLFP, IE ni la SR. El numero de ovocitos fue mayor (p 0,05) entre las vaquillas del tratamiento rbST-I y rbST-II. Ademas, del 36,8% de donadoras de ambos tratamientos no se colecto ningun ovocito o embrion. Conclusion : la aplicacion de 500 mg de rbST los dias -8 y cero del protocolo de sincronizacion de la onda folicular no incremento la respuesta superovulatoria pero redujo significativamente el numero de ovocitos recolectados de vaquillas Holstein superovuladas. Palabras clave: foliculo preovulatorio, incidencia de celo, novillas donadoras, tasa de concepcion. Resumo Antecedentes : a somatotropina bovina recombinante (rbST) tem sido aplicada em vacas doadoras de embrioes com o objetivo de melhorar a resposta superovulatoria e a qualidade embrionaria. Objetivo : o presente trabalho avaliou o efeito da aplicacao de uma contra duas injecoes de 500 mg de rbST em novilhas de raca Holandesa doadoras de embrioes na incidencia do cio (IE), diâmetro do maior foliculo pre-ovulatorio (dLFP), resposta superovulatoria (SR), producao de embrioes e taxa de gestacao em vacas receptoras de raca Holandesa (PRR). Metodos : foram feitos dois programas de superestimulacao, em cada superstimulacao as novilhas foram distribuidas em um de dois tratamentos: 1) rbST-I, n = 5: as novilhas receberam uma injecao de rbST no dia zero (dia de remocao do CIDR -dispositivo intravaginal de liberacao controlada de progesterona). 2) rbST-II, n = 5: as novilhas receberam a primeira injecao de rbST no dia -8 e a segunda injecao no dia zero. Trinta e oito vacas foram utilizadas como receptoras e receberam um embriao proveniente de uma doadora de um dos dois tratamentos. Resultados : a aplicacao de uma ou duas injecoes de rbST nao afetou (p > 0,05) a PRR, dLFP, IE nem a SR. O numero de oocitos foi maior (p 0,05) entre as novilhas do tratamento rbST-I e rbST-II. Alem disso, do 36.8% das doadoras de ambos os tratamentos nao foi possivel coletar nenhum oocito ou embriao. Conclusoe s: A aplicacao de 500 mg de rbST o dia -8 e zero do protocolo de sincronizacao da onda folicular nao aumentou a resposta superovulatoria, mas diminuiu significativamente o numero de oocitos coletados de novilhas de raca Holandesa superovuladas. Palavras chave: foliculo pre-ovulatorio, incidencia do cio, novilhas doadoras, taxa de gestacao.

Body weight in different mammalian species influences reproductive potential. The aim of the present study was to determine the relationship of body weight at the time of semen collection with libido, seminal characteristics and number of semen doses for artificial insemination (AI) in New Zealand White mature fertile male rabbits. Data came from 728 semen collections of 14 rabbits, 15-months of age that were sexually experienced with proven semen quality and fertility. Semen collection was performed twice a week with two ejaculates at each collection time and lasted 14 weeks. A second ejaculation was collected at 1-2h after the first. Data from each male from first and second ejaculates from 1 day of semen collection throughout the trial were averaged (n=324) and partial correlation coefficients and regression equations were estimated to describe the relationship of male body weight to ejaculation reaction time and 12 semen and sperm characteristics. As body weight increased there was a linear (P0.05) increase in reaction time, abnormal sperm with an intact membrane and abnormal sperm with a damaged membrane and a linear (P0.05) decrease in semen volume, sperm concentration per ejaculate, normal sperm with an intact membrane, number of normal motile sperm with an intact membrane and suitable semen doses for AI. Body weight of the mature male rabbit at semen collection had some influence on libido, semen and sperm characteristics, with a general trend toward a lesser reproduction potential as body weight increases.

This study evaluated the effect of injecting vitamin C (VC) and E (VE) on size of the preovulatory follicle, volume of the corpus luteum, and pregnancy rates in Holstein cows under heat stress conditions (temperature humidity index > 74). Sixty-two cows were randomly assigned to one of four treatments: 1, control, n = 15: cows were not supplemented with vitamins; 2, VCG, n = 15: cows were simultaneously injected i.v. with 500 and s.c. with 2500 mg of VC before and after estrus; 3, VEG, n = 15: cows received an i.m. injection of 3000 IU of VE before estrus; 4, VCEG, n = 17: cows were injected with VC and VE in the same way and doses as in treatments 2 and 3. Treatment did not significantly affect any of the measured variables, despite a numerical increase in pregnancy rates in cows injected with vitamins (7.5 ± 7.3%, 9.6 ± 9.4%, 15.1 ± 10.0%, and 18.34 ± 9.9% for control, VCG, VEG, and VCEG, respectively). In conclusion, injections of vitamin C and E did not affect either the development of the preovulatory follicle and the corpus luteum or pregnancy rates in Holstein dairy cattle under heat stress conditions.

The sprouted wheat (SW) contains the 6-methoxy-2-benzoxazolinone (6-MBOA), a phenol compound that stimulates reproduction in certain small wild herbivorous mammals. The objective of the present study was to evaluate the effect of short-term supplemental dietary SW on libido, semen and sperm characteristics of rabbit bucks. Five-month old New Zealand White pubertal rabbits (n=18) were randomly allocated to one of two treatments: supplementation or not (control) supplemented with SW. The experimental design was completely random with nine replications, experimental unit was one buck. Semen collection for each male was conducted once a week with two ejaculations during 20 weeks. The SW was given during four consecutive days prior to each semen collection. Analysis of variance was under a mixed model: treatment, ejaculate number and season were fixed and rabbit random effects. There was no effect of treatment (P>0.05) on reaction time, gel presence, volume, pH, sperm motility, sperm number per ml and sperm number per ejaculate. The percentage of normal alive spermatozoa was 13.5% greater in SW-supplemented bucks than in the control and the percentage of abnormal alive spermatozoa was 44.1% greater in the control than in the SW-supplemented bucks. The morphology of dead spermatozoa, integrity of acrosome, number of normal alive motile sperm and semen doses per ejaculate were not influenced (P>0.05) by SW supplementation. The proportion of presence of gel and semen volume in the first ejaculate was greater than the second ejaculate (+140% and +56.4%). However, the semen quality in the latter was greater (P=0.0001) than the former in terms of an increase in motility (+29.7%). Reproductive traits were more desirable (P

Female exposure of males could be a low-cost biostimulation option that benefits AI in commercial rabbit operations by improving buck rabbits reproductive performance. The objective of the study was to evaluate exposure of buck rabbits to females as a biostimulation option to improve reproductive potential. Treatments were: exposure (biostimulated) or not (control) of bucks to does. Bucks were New Zealand White, 15-month-old, sexually experienced and fertile. Experimental design was completely random with nine replications, experimental unit was one buck. Doe exposure was permanent using replacement pubertal does housed in an adjacent wire-mesh cage and changed for new ones every other week. Semen collection lasted 14 weeks (late winter and early spring) twice a week with two ejaculates at each collection. Analyses of variance were under a mixed model: treatments, ejaculate number and season were fixed and rabbit random effects and buck weight at each collection as covariable. Biostimulated bucks showed greater (P0.05) reproductive potential due to: 7% lesser reaction time (greater libido); and increased semen volume (40%), sperm motility (29%), sperm per ejaculate (31%), normal alive motile sperm (65%) and number of semen doses (64%). Semen characteristics differed by season in control bucks but not in doe exposed bucks (treatment × ejaculate number, P0.05). Reproductive potential in spring was greater (P0.05) than in winter in both treatments. Doe exposure is a biostimulation method that improves sexual drive and sperm production and quality of buck rabbits.

A study was conducted to evaluate the effect of short-term relocation and male exposure on receptivity rate, kindling rate and total born per litter in lactating does under an artificial insemination (AI) programme. Thirty-two, 2-month-old New Zealand White rabbits were randomly allocated to one of four treatments: (1) relocation and male exposure; (2) relocation without male exposure; (3) no relocation with male exposure; (4) no relocation without male exposure (control). Relocation and male exposure were done 8-10 h before the time of service. First insemination was when does reached 3200 g body weight and does were bred 4-13 days after parturition across parities during a 6 month reproduction period. Of all breeding records, 125 inseminations and 91 kindlings were from nursing does. The mean interval from parturition to insemination for nursing does was 10.3 days. Relocation of lactating does resulted in greater (P0.01) receptivity rate at service (74.8%) as compared with no relocation (55%). Receptivity rate was not influenced by male exposure. However, the interaction of relocationxmale exposure tended to be significant (P=0.07). Receptivity rate in relocated does exposed to males was 62.8 and 86.7% without exposure while in non-relocated does male exposure showed no effect. Kindling rate was not influenced by relocation or male exposure. The mean total born per litter in relocated and non-relocated does was 8.05 +/- 0.33 and 7.39 +/- 0.36, respectively, but no significant difference was observed. There was no effect of male exposure on total born per litter (7.85 +/- 0.34 versus 7.59 +/- 0.34 without male exposure). However, interaction of relocationxmale exposure on this variable was significant (P=0.009). Male exposure in relocated does decreased the size of the litter (7.52 +/- 0.46 versus 8.58 +/- 0.47 without male exposure) whereas mean values in non-relocated does increased when they were exposed to males (8.18 +/- 0.52 versus 6.60 +/- 0.49). Short-term relocation improved receptivity rate and reproduction in lactating does under an artificial insemination programme. Preliminary results indicated that male exposure in non-relocated does improves the total born per litter at a similar level than relocated does without male exposure. Relocation combined with male exposure decreased receptivity rate and total born per litter as compared with relocated does without male exposure, but the reproductive performance in the former was greater as compared with those does where no relocation occurred without male exposure.

The sprouted wheat contains great amounts of 6-methoxybenzoxazolinone (6-MBOA) a phenol compound that stimulates reproduction in certain small wild herbivorous mammals. The objective of the present study was to evaluate the effect of dietary sprouted wheat as supplement on reproduction in artificially inseminated doe rabbits. Two-month-old New Zealand White doe rabbits (n = 48) were randomly allocated to one of two treatments: (1) pelleted diet plus sprouted wheat for 6 consecutive days prior to service, (2) pelleted diet only (control). First insemination occurred when does reach 3200g body weight and bred 6 days after parturition across 6 months period during summer and autumn. Records from 41 does completing the experiment accounted for 192 inseminations and 142 kindlings equivalent to 4.6 +/- 0.15 and 3.5 +/- 0.15 litters per doe, respectively. Mean daily intake of sprouted wheat on wet and dry matter bases were 196.1 +/- 7.5 and 75.4 +/- 2.9g, respectively. The number of young born produced per doe during the trail was significantly (P = 0.02) greater in does fed sprouted wheat (28.1 +/- 1.2 versus 23.6 +/ -1.3 control). Does fed sprouted wheat had 0.65 +/- 0.06 receptivity rate at AI over 28 per cent greater (P = 0.001) than does in the control treatment. Sexual receptivity was not influenced by physiological status of does and season (P0.05). Diet and season had no effect (P0.05) on kindling rate. However, physiological status had an effect (P = 0.002) on this variable. Kindling rates for nulliparous, lactating and non-lactating does were 0.95 +/- 0.08, 0.63 +/- 0.04 and 0.78 +/ -0.11, respectively. Sexually receptive does had a greater (P = 0.0001) kindling rate (0.95 +/- 0.05) than non-receptive females (0.63 +/-0.05). Does fed sprouted wheat produced larger (P = 0.02) litters than those in the control group: 7.7 +/- 0.30 and 6.8 +/- 0.32, respectively. There was an effect of season (P = 0.04) on the size of the litter at birth. Largest litters were born during autumn (7.9 +/- 0.37) than during summer (6.6 +/- 0.41). Receptive does had more (P = 0.002) young in the litter (7.9 +/- 0.28) than non-receptive (6.6 +/- 0.35). Feeding sprouted wheat as a source of biological 6-MBOA enhanced sexual receptivity and prolificacy in artificially inseminated doe rabbits bred in summer and autumn.

[EN] A total of 713 inseminations and 431 kindling records were used for statistical analysis to determine the fixed effects of season, sexual receptivity and physiological status on kindling rates (KR) and total born per litter (TB). Rabbits were reared in México under a moderate climate located at 2240 m above sea leve! with an average yearly temperature of 15ºC. Eighty four New Zealand White rabbits two months of age were reared in a 64-cage replacement system and bred throughout a one-year reproduction cycle. Does kept in 32 cages were inseminated regularly 4-8 days after parturition while does maintained in the other 32 cages were under a 9-13 days reproductive rhythm. Season had no influence on reproductive performance (P>0.05). Kindling rates for spring, summer, autumn and winter were 0.67, 0.67, 0.66, and 0.65 respectively, with TB values of 8.35 ± 0.26, 8.06 ± 0.25, 8.03 ± 0.27 and 7.86 ± 0.40 respectively. Does that were sexually receptive at insemination had significantly (P, [FR] Une analyse statistique, portan! sur les données enregistrées de 713 inséminations et 431 mises bas, a été effectuée pour déterminer l'effet fixe de la saison, de la réceptivité sexuelle et du stade physiologique sur le taux de mise bas (KR) et le nombre total de lapereaux par portée (TB). Ces lapins ont été élevés au Mexique, sous un clima! modéré a 2240m d'altitude avec une température moyenne annuelle de 15ºC. Quatre-vingtquatre lapines NZW sélectionnées a l'age de 2 mois ont été élevés pendan! un cycle de reproduction d'un an dans un ensemble de 64 cages avec remplacement des sujets morts ou réformés. Les lapines, logées dans 32 des cages, ont été réguliérement inséminées 4-8 jours aprés la mise bas, tandis que celles des 32 autres cages l'ont été 9-13 jours aprés la mise bas. La saison n'a pas eu d'influence sur les performances de reproduction (P>0.05). Le taux de mise bas au printemps, en été, a l'automne et en hiver a été de 0,67 ; 0,67 ; 0,66 et 0,65 respectivement avec des nombres de lapereaux nés de (TB) 8,35 ± 0,26 ; 8,06 ± 0,25 ; 8,08 ± 0,27 et 7,86 ± 0,40 respectivement. Les femelles sexuellement réceptives a l'insémination ont eu un taux de mise bas significativement (P

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. Key words: embryo, fertility, free radicals, oocytes, ovulation, oxidative stress. Resumen El estres oxidativo es generado por un desbalance entre radicales libres y antioxidantes. Bajo condiciones fisiologicas normales, los radicales libres participan en eventos reproductivos tales como activacion del ciclo celular, ovulacion y luteolisis. Sin embargo, cuando estos son producidos en cantidades que sobrepasan la capacidad antioxidante del organismo producen dano oxidativo y trastornos reproductivos que disminuyen la fertilidad de la hembra. La suplementacion con antioxidantes previene el dano oxidativo y su incorporacion a programas de manejo reproductivo puede ser una opcion para mejorar la fertilidad de la hembra. La seleccion del foliculo preovulatorio, ovulacion, fecundacion, desarrollo embrionario y formacion del cuerpo luteo ocurren durante el periodo periconcepcional. Este es un periodo dinamico y los eventos que ocurren en el son susceptibles a dano por estres oxidativo. Por tanto, el objetivo de esta revision es discutir el efecto del estres oxidativo en los eventos reproductivos durante el periodo periconcepcional, asi como la suplementacion de antioxidantes en rumiantes durante este periodo. Palabras clave: embrion, estres oxidativo, fertilidad, ovocito, ovulacion, radicales libres. Resumo O stress oxidativo e gerado por um desequilibrio entre radicais livres e antioxidantes. Sob condicoes fisiologicas normais, os radicais livres participam de eventos reprodutivos, como ativacao do ciclo estral, ovulacao e luteolise. No entanto, quando e produzido em quantidades que excedem a capacidade antioxidante do organismo, produzem danos oxidativos e disturbios reprodutivos que diminuem a fertilidade da femea. A suplementacao com antioxidantes previne o dano oxidativo e sua incorporacao em programas de gerenciamento reprodutivo pode ser uma opcao para melhorar a fertilidade da femea. A selecao do foliculo pre-ovulatorio, ovulacao, fecundacao, desenvolvimento embrionario e formacao do corpo luteo ocorrem durante o periodo periconcepcional. Este e um periodo dinâmico e os eventos que ocorrem sao suscetiveis ao dano por estresse oxidativo. Portanto, o objetivo dessa revisao e fornecer ao leitor conhecimento sobre o efeito do estresse oxidativo em eventos reprodutivos durante o periodo periconcepcional, e tambem discutir a suplementacao com antioxidantes em ruminantes durante este periodo. Palavras-chave: embriao, estresse oxidativo, fertilidade, ovocito, ovulacao, radicais livres.