RESUMEN

Glucose metabolism adapts to gestation, resulting in progressive physiological insulin resistance and increased insulin secretion to maintain maternal euglycemia and glucose availability for the developing fetus. These changes can impact mare fertility and maternal and neonatal health. This is the first comparison of body condition, regional adiposity, insulin and glucose dynamics, lipid metabolism, and cytokine production between lactating and non-lactating mares before, during pregnancy, and early postpartum. Twelve pregnancies from 9 broodmares, five nonlactating (NL) and seven lactating (L), were used. Evaluations were performed on the day of ovulation, at 55, 110, 165, 220, 275, and 330 days of gestation (D55, D110, D165, D220, D275, D330) and 21 days postpartum (21pp). Mares in the L group had lower basal insulin and glucose at the beginning of pregnancy, smaller area under the curve of insulin and glucose, and greater insulin sensitivity and glucose tolerance. Resistin was higher in D110 and D165 than in D0, D275, 330 and 21pp, while leptin was higher in D55, and in D110, at D110 it was equal to D0, D220, and D275, but higher than at D330 and D21pp. As for the groups, L presented lower body condition score (BCS), crest neck score (CNS), rump fat thickness (RUM), basal insulin, glucose area under the curve (AUCg), MIRG and higher RISQI, adiponectin and tumor necrosis factor (TNFα). There was no effect over time in non-esterified fatty acids (NEFA) concentrations between the L mares; in the NL, D275 presented higher concentrations than those of D0, D55, and D110, which in turn were equal to the other time points; there were higher concentrations in NL mares than L in samples D165 and D275. In conclusion, a different metabolic profile during pregnancy was detected, and NL mares were closer to the metabolic threshold for the occurrence of metabolic syndrome during pregnancy. Understanding the impacts of these differences on mare's health and their offspring's future is fundamental as most of our recipient mares for embryo transfer are non-lactating. Therefore, we suggest that further studies be performed to evaluate lactation's influence on mares' metabolic parameters.

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After parturition, a rapid transition occurs from the intrauterine to the extrauterine milieu, exposing neonates to physiological circumstances characterized by oxidative conditions that instigate the generation of reactive oxygen species. These free radicals play pivotal roles in physiological processes; however, an imbalance between their production and the removal of antioxidants can result in severe cellular damage. The main objective of this study was to compare the oxidative and antioxidant profiles in mule and horse neonates immediately post-parturition, as well as at subsequent time points (1, 6, 12, and 24 h, 7 and 30 days) during their extrauterine existence. The parameters assessed included the systemic concentrations of Thiobarbituric Acid Reactive Substances (TBARS) and carbonyl groups; the activities of the antioxidants superoxide dismutase (SOD) and glutathione peroxidase (GPx); and the levels of the total, indirect, and direct bilirubin. Our results showed no interaction effect between the neonatal groups and the assessed time points for the variables under investigation. Notably, the concentrations of TBARS, as a marker of lipid peroxidation, and bilirubin were consistently lower in the mules, whereas the glutathione peroxidase (GPx) activity exhibited higher levels in this group. The bilirubin levels were notably reduced in the mule neonates. The TBARS demonstrated a progressive decrease over the observation period in both groups, while the GPx activity remained relatively stable from birth to 7 days, with a substantial increase evident at the 30-day mark. Protein oxidation was not affected by the group and time, while for the SOD values, all times were statistically similar, except for the lower activity at T1h. Consequently, our findings lead us to the conclusion that neonatal mules and horses manifest distinct patterns of oxidative activity and antioxidant capacity during the initial month of their extrauterine existence, potentially indicative of different adaptation mechanisms to the extrauterine environment.

RESUMEN

Establishment of pregnancy after embryo transfer is the ultimate goal of an embryo transfer program and increasing pregnancy rates and reducing pregnancy loss are mandatory. The utilization of treatments to improve conception rates in recipient mares has been the focus of several research groups over the last years and the results are controversial. Some studies using human chorionic gonadotrophin (hCG) found promising results. Our hypothesis was that hCG administration would cause an additional stimulation on luteal function, uterine and luteal vascularization and progesterone concentration, and the mares would have increased uterine and cervix tone. Therefore, in the present study the effects of hCG administration to induce ovulation, on day 0 (day of ovulation) or day 5 postovulation were evaluated on corpus luteum characteristics, reproductive tract vascularization, and serum progesterone concentration from ovulation until day 15 postovulation. Groups were: G1: (control) - no hCG; G2: 2500 IU of hCG to induce ovulation when a follicle greater than 35mm and uterine edema were detected; G3: 2500 IU hCG on day 0; G4: 2500 IU hCG on day 5 postovulation. Twelve mares were randomly assigned to each group, during consecutive cycles, in a Latin Square experimental design, in a total of 48 cycles. Doppler ultrasound evaluations were performed daily from day 0 until day 15 postovulation, including mesometrial vascularity, endometrial vascularity and corpus luteum vascularity. Blood samples were collected for serum progesterone concentration. Data was analyzed using the Proc Glimmix SAS Procedure for nonparametric variables and Proc Mixed for parametric parameters. There was no treatment effect for all variables studied (P > 0.05). Characteristics were only affected by day (P < 0.05). It can be concluded that hCG administration at the time points suggested in the current study did not alter the characteristics evaluated.

RESUMEN

Establishment of pregnancy after embryo transfer is the ultimate goal of an embryo transfer program and increasing pregnancy rates and reducing pregnancy loss are mandatory. The utilization of treatments to improve conception rates in recipient mares has been the focus of several research groups over the last years and the results are controversial. Some studies using human chorionic gonadotrophin (hCG) found promising results. Our hypothesis was that hCG administration would cause an additional stimulation on luteal function, uterine and luteal vascularization and progesterone concentration, and the mares would have increased uterine and cervix tone. Therefore, in the present study the effects of hCG administration to induce ovulation, on day 0 (day of ovulation) or day 5 postovulation were evaluated on corpus luteum characteristics, reproductive tract vascularization, and serum progesterone concentration from ovulation until day 15 postovulation. Groups were: G1: (control) - no hCG; G2: 2500 IU of hCG to induce ovulation when a follicle greater than 35mm and uterine edema were detected; G3: 2500 IU hCG on day 0; G4: 2500 IU hCG on day 5 postovulation. Twelve mares were randomly assigned to each group, during consecutive cycles, in a Latin Square experimental design, in a total of 48 cycles. Doppler ultrasound evaluations were performed daily from day 0 until day 15 postovulation, including mesometrial vascularity, endometrial vascularity and corpus luteum vascularity. Blood samples were collected for serum progesterone concentration. Data was analyzed using the Proc Glimmix SAS Procedure for nonparametric variables and Proc Mixed for parametric parameters. There was no treatment effect for all variables studied (P > 0.05). Characteristics were only affected by day (P < 0.05). It can be concluded that hCG administration at the time points suggested in the current study did not alter the characteristics evaluated.

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Apesar de pertencerem à mesma família Equidae, sabe-se que os asininos (Equus asinus, 2n:62) possuem características comportamentais e fisiológicas diferentes dos equinos (Equus caballus,2n:64). Além disso, os neonatos apresentam os parâmetros vitais em constante modificação ao longo dos eventos pós-natais. Desta forma, o conhecimento dos valores de referência, e a influência da idade nos parâmetros etológicos, clínicos e laboratoriais nas diferentes espécies é uma ferramenta fundamental para correta avaliação neonatal. Por essa razão, o objetivo desta revisão é abordar de forma comparativa os parâmetros de vitalidade e comportamentais dos neonatos asininos e equinos, bem como os parâmetros laboratoriais nos primeiros meses de vida.

Although they belong to the same family Equidae, it is known that the donkeys (Equus asinus, 2n:62) have different behavioral and physiological characteristics from the equine (Equus caballus, 2n:64). In addition, newborns present vital parameters in constant modification throughout the postnatal events. Therefore, the knowledge of reference values and the influence of age on postnatal behavior, clinical and laboratory parameters in the different species is a fundamental tool for correct neonatal evaluation. Thus, the objective of this review is to compare the vitality and behavioral parameters of the donkey and equine neonates, as well as the laboratory parameters during the first months of life.

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O metabolismo de glicose se adapta à gestação e lactação em várias espécies, incluindo os equinos. Essa adaptação envolve tanto o desenvolvimento progressivo fisiológico de resistência à insulina no tecido alvo, quanto o aumento na secreção de insulina pelas células β pancreáticas. A resistência a insulina, hiperinsulinemia e obesidade ou aumento da adiposidade regional são os três componentes principais da Síndrome Metabólica Equina. Ela pode levar à laminite, subfertilidade em éguas e garanhões, maior risco de distocias e aumento da chance de doenças ortopédicas e deformidades angulares em potros. Em humanos, as adaptações hematobioquímicas da gestação são conhecidas e os valores de referência em exames laboratoriais são diferentes entre mulheres gestantes e não gestantes. Em equinos ainda não existem estes valores para diagnóstico de resistência à insulina e/ou Diabetes Mellitus Gestacional em éguas prenhes. Desta forma, o objetivo desse trabalho é traçar um paralelo entre o descrito em mulheres gestantes e equinos.

Glucose metabolism adapts to gestation and lactation in several species, including horses. This adaptation involves the progressive physiological development of insulin resistance in target tissues and the increase in insulin secretion by pancreatic β cells. Insulin resistance and hyperinsulinemia together with obesity or increased regional adiposity are the three main components of Equine Metabolic Syndrome (EMS). EMS causes alterations in several systems of the body, leading to laminitis, fertility problems in mares and stallions, increased risk of dystocia and chance of orthopedic diseases and angular deformities in foals from affected mares. In humans, it is well known that due to the hematobiochemical adaptations of pregnancy, the reference values in laboratory tests are different between pregnant and non-pregnant women. Currently in equine, there are no reference values to diagnose insulin resistance and / or Gestational Diabetes Mellitus (GDM). Therefore, the objective of this review is to establish a parallel between what has been described in pregnant women and mares.

Asunto(s)

RESUMEN

O metabolismo de glicose se adapta à gestação e lactação em várias espécies, incluindo os equinos. Essa adaptação envolve tanto o desenvolvimento progressivo fisiológico de resistência à insulina no tecido alvo, quanto o aumento na secreção de insulina pelas células β pancreáticas. A resistência a insulina, hiperinsulinemia e obesidade ou aumento da adiposidade regional são os três componentes principais da Síndrome Metabólica Equina. Ela pode levar à laminite, subfertilidade em éguas e garanhões, maior risco de distocias e aumento da chance de doenças ortopédicas e deformidades angulares em potros. Em humanos, as adaptações hematobioquímicas da gestação são conhecidas e os valores de referência em exames laboratoriais são diferentes entre mulheres gestantes e não gestantes. Em equinos ainda não existem estes valores para diagnóstico de resistência à insulina e/ou Diabetes Mellitus Gestacional em éguas prenhes. Desta forma, o objetivo desse trabalho é traçar um paralelo entre o descrito em mulheres gestantes e equinos.(AU)

Glucose metabolism adapts to gestation and lactation in several species, including horses. This adaptation involves the progressive physiological development of insulin resistance in target tissues and the increase in insulin secretion by pancreatic β cells. Insulin resistance and hyperinsulinemia together with obesity or increased regional adiposity are the three main components of Equine Metabolic Syndrome (EMS). EMS causes alterations in several systems of the body, leading to laminitis, fertility problems in mares and stallions, increased risk of dystocia and chance of orthopedic diseases and angular deformities in foals from affected mares. In humans, it is well known that due to the hematobiochemical adaptations of pregnancy, the reference values in laboratory tests are different between pregnant and non-pregnant women. Currently in equine, there are no reference values to diagnose insulin resistance and / or Gestational Diabetes Mellitus (GDM). Therefore, the objective of this review is to establish a parallel between what has been described in pregnant women and mares.(AU)

Asunto(s)

RESUMEN

Apesar de pertencerem à mesma família Equidae, sabe-se que os asininos (Equus asinus, 2n:62) possuem características comportamentais e fisiológicas diferentes dos equinos (Equus caballus,2n:64). Além disso, os neonatos apresentam os parâmetros vitais em constante modificação ao longo dos eventos pós-natais. Desta forma, o conhecimento dos valores de referência, e a influência da idade nos parâmetros etológicos, clínicos e laboratoriais nas diferentes espécies é uma ferramenta fundamental para correta avaliação neonatal. Por essa razão, o objetivo desta revisão é abordar de forma comparativa os parâmetros de vitalidade e comportamentais dos neonatos asininos e equinos, bem como os parâmetros laboratoriais nos primeiros meses de vida.(AU)

Although they belong to the same family Equidae, it is known that the donkeys (Equus asinus, 2n:62) have different behavioral and physiological characteristics from the equine (Equus caballus, 2n:64). In addition, newborns present vital parameters in constant modification throughout the postnatal events. Therefore, the knowledge of reference values and the influence of age on postnatal behavior, clinical and laboratory parameters in the different species is a fundamental tool for correct neonatal evaluation. Thus, the objective of this review is to compare the vitality and behavioral parameters of the donkey and equine neonates, as well as the laboratory parameters during the first months of life.(AU)

Asunto(s)

RESUMEN

Establishment of pregnancy after embryo transfer is the ultimate goal of an embryo transfer program and increasing pregnancy rates and reducing pregnancy loss are mandatory. The utilization of treatments to improve conception rates in recipient mares has been the focus of several research groups over the last years and the results are controversial. Some studies using human chorionic gonadotrophin (hCG) found promising results. Our hypothesis was that hCG administration would cause an additional stimulation on luteal function, uterine and luteal vascularization and progesterone concentration, and the mares would have increased uterine and cervix tone. Therefore, in the present study the effects of hCG administration to induce ovulation, on day 0 (day of ovulation) or day 5 postovulation were evaluated on corpus luteum characteristics, reproductive tract vascularization, and serum progesterone concentration from ovulation until day 15 postovulation. Groups were: G1: (control) - no hCG; G2: 2500 IU of hCG to induce ovulation when a follicle greater than 35mm and uterine edema were detected; G3: 2500 IU hCG on day 0; G4: 2500 IU hCG on day 5 postovulation. Twelve mares were randomly assigned to each group, during consecutive cycles, in a Latin Square experimental design, in a total of 48 cycles. Doppler ultrasound evaluations were performed daily from day 0 until day 15 postovulation, including mesometrial vascularity, endometrial vascularity and corpus luteum vascularity. Blood samples were collected for serum progesterone concentration. Data was analyzed using the Proc Glimmix SAS Procedure for nonparametric variables and Proc Mixed for parametric parameters. There was no treatment effect for all variables studied (P > 0.05). Characteristics were only affected by day (P < 0.05). It can be concluded that hCG administration at the time points suggested in the current study did not alter the characteristics evaluated.(AU)

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RESUMEN

Follicular development and deviation processes during the postpartum period are not completely known in horses. Thus, we aimed to study the characteristics of follicular dynamics and ovarian vascular perfusion during the postpartum period in mares that demonstrated estrous behavior and had early (<10 days) or late (≥10 days) postpartum ovulation. Ten mares were scanned daily by transrectal ultrasonography from the first day postpartum (d1) to the sixteenth day after the first postpartum ovulation (D0 = ovulation). The animals were split in the early (n = 3) and late (n = 7) ovulation groups (average interval between parturition and ovulation: 8.0 ± 0.0 and 14.7 ± 1.2 days, respectively). For the follicular growth, no difference (P > 0.1) was detected between the groups when the data were normalized for the days preceding the first postpartum ovulation (from D-7 to D-1). However, when the data were normalized to days postpartum, the dominant follicle was larger (P < 0.05) in the early-ovulated group in all days during this period (d1 to d7). The number of follicles >25 mm diameter was greater (P < 0.05) in the early-ovulated group during the first 3 days postpartum, and the late-ovulated mares showed greater number of follicles with 20-25 mm during d4 to d7. For blood flow characteristics, no difference (P > 0.1) was detected between groups in vascular perfusion of the dominant follicle or in the ovarian pedicle ipsilateral to the largest follicle. Similarly, no difference (P > 0.1) was detected in progesterone concentrations, corpus luteum (CL) area and vascular perfusion of the CL. Pregnancy rate did not differ (P > 0.1) between the early (3/3; 100%) and late (5/7; 71.4%) groups. Therefore, the characteristics of the follicle growth on the preceding days of ovulation were similar between the early- and late-ovulated mares and were consistent with the follicular dynamics expected in non-pregnant and non-lactating mares. However, when the data were analyzed for the days relative to parturition, greater follicle development was present in mares that ovulate earlier during the postpartum period (<10 days). The results suggest that important events may occur before parturition, resulting in early follicle development, mainly in those mares that show estrus and ovulate within 10 days postpartum.

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Uma placenta normal e eficiente que desempenhe suas funções é um pré-requisito indispensável paraque a gestação seja conduzida com sucesso, permitindo o desenvolvimento e maturação fetal e resultando nonascimento de um produto sadio e com desenvolvimento adequado. Assim, um conjunto de avaliações queforneçam dados sobre as características maternas, eficiência placentária e monitoramento da gestação são deextrema importância para a criação e o mercado equestre. Têm sido demonstrada uma relação entra ascaracterísticas macro e microscópicas da placenta e viabilidade de potros ao nascimento. Dessa forma, oconhecimento das mudanças na estrutura e função placentária que são influenciadas pelo porte, idade e paridadematerna, e por sua vez, possam refletir no desenvolvimento e crescimento do feto, são de grande importânciapara uma melhor seleção e manejo das matrizes e/ou receptoras, que serão responsáveis por gestar um potro.

A normal and efficient placenta that fulfills its functions is an essential prerequisite in order to have aterm pregnancy, allowing fetal development and maturation resulting in the birth of a healthy, well developedfoal. Therefore, several evaluations that provide information on maternal characteristics, placental efficiencyand pregnancy monitoring are of extreme importance for equine breeding industry. A relationship betweenmacro and microscopic placental characteristics and foals’ viability at birth has been detected. Thus, theknowledge of the changes of structure and placental function that are influenced by size, age and maternalparity which can reflect in development and growth of the fetus are of major importance for a better selectionand management of broodmares and/or recipients that will carry a foal to term.

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Muitos são os hormônios envolvidos no período de gestação da égua, sendo um evento muito complexodo que um simples predomínio progesterônico como muitos acreditam. Da mesma forma, o processo do parto,não é atribuído a um gatilho hormonal isolado, mas sim uma cascata de alterações endócrinas que atuam em umasequência ordenada. Estes hormônios circulantes na égua gestante, são produzidos por precursores fetais,metabolizados na placenta e com principal ação no útero materno. Embora a maioria dos hormônios envolvidosna gestação e parto sejam comuns entre as espécies de mamíferos, alguns aspectos da secreção degonadotrofinas, progesterona e esteroides pela unidade feto-placentária são exclusivos na égua. Assim, oconceito de cooperação interdependente entre placenta, feto e endométrio torna-se fundamental nessa espécie,primando a manutenção da gestação, desenvolvimento fetal e desencadeamento do parto.

Several hormones are involved throughout pregnancy and it is a lot more complex than theprogesterone predominance as believed. Likewise, the process of parturition is not an event attributed to anisolated hormonal trigger but a cascade of endocrinological alterations that act in a coordinated sequence.These circulating hormones in the pregnant mare are produced by fetal precursors, metabolized by the placentaand act mainly in maternal uterus. Although most hormones involved in pregnancy and parturition are commonamong mammalian species, some aspects of fetoplacental secretion of gonadotrophins, progesterone andsteroids are unique in the mare. Thus, the concept of interrelationship between placenta, fetus and endometriumis fundamental in this species, aiming pregnancy maintenance, fetal development and triggering of parturition.

Asunto(s)

RESUMEN

Uma placenta normal e eficiente que desempenhe suas funções é um pré-requisito indispensável paraque a gestação seja conduzida com sucesso, permitindo o desenvolvimento e maturação fetal e resultando nonascimento de um produto sadio e com desenvolvimento adequado. Assim, um conjunto de avaliações queforneçam dados sobre as características maternas, eficiência placentária e monitoramento da gestação são deextrema importância para a criação e o mercado equestre. Têm sido demonstrada uma relação entra ascaracterísticas macro e microscópicas da placenta e viabilidade de potros ao nascimento. Dessa forma, oconhecimento das mudanças na estrutura e função placentária que são influenciadas pelo porte, idade e paridadematerna, e por sua vez, possam refletir no desenvolvimento e crescimento do feto, são de grande importânciapara uma melhor seleção e manejo das matrizes e/ou receptoras, que serão responsáveis por gestar um potro.(AU)

A normal and efficient placenta that fulfills its functions is an essential prerequisite in order to have aterm pregnancy, allowing fetal development and maturation resulting in the birth of a healthy, well developedfoal. Therefore, several evaluations that provide information on maternal characteristics, placental efficiencyand pregnancy monitoring are of extreme importance for equine breeding industry. A relationship betweenmacro and microscopic placental characteristics and foals viability at birth has been detected. Thus, theknowledge of the changes of structure and placental function that are influenced by size, age and maternalparity which can reflect in development and growth of the fetus are of major importance for a better selectionand management of broodmares and/or recipients that will carry a foal to term.(AU)

Asunto(s)

RESUMEN

Muitos são os hormônios envolvidos no período de gestação da égua, sendo um evento muito complexodo que um simples predomínio progesterônico como muitos acreditam. Da mesma forma, o processo do parto,não é atribuído a um gatilho hormonal isolado, mas sim uma cascata de alterações endócrinas que atuam em umasequência ordenada. Estes hormônios circulantes na égua gestante, são produzidos por precursores fetais,metabolizados na placenta e com principal ação no útero materno. Embora a maioria dos hormônios envolvidosna gestação e parto sejam comuns entre as espécies de mamíferos, alguns aspectos da secreção degonadotrofinas, progesterona e esteroides pela unidade feto-placentária são exclusivos na égua. Assim, oconceito de cooperação interdependente entre placenta, feto e endométrio torna-se fundamental nessa espécie,primando a manutenção da gestação, desenvolvimento fetal e desencadeamento do parto.(AU)

Several hormones are involved throughout pregnancy and it is a lot more complex than theprogesterone predominance as believed. Likewise, the process of parturition is not an event attributed to anisolated hormonal trigger but a cascade of endocrinological alterations that act in a coordinated sequence.These circulating hormones in the pregnant mare are produced by fetal precursors, metabolized by the placentaand act mainly in maternal uterus. Although most hormones involved in pregnancy and parturition are commonamong mammalian species, some aspects of fetoplacental secretion of gonadotrophins, progesterone andsteroids are unique in the mare. Thus, the concept of interrelationship between placenta, fetus and endometriumis fundamental in this species, aiming pregnancy maintenance, fetal development and triggering of parturition.(AU)

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O estresse oxidativo é prejudicial a diversas características espermáticas, como motilidade e integridade das membranas plasmática, acrossomal e mitocondrial, podendo levar a redução da fertilidade, inclusive no sêmen refrigerado. Poucos estudos foram realizados utilizando-se a melatonina com o intuito de melhorar as características espermáticas em equinos. O mioinositol e o ácido ferúlico, por sua vez, nunca foram utilizados nessa espécie. O presente trabalho teve como objetivo avaliar a influência desses compostos nas características do sêmen equino refrigerado. Para isso, foram utilizadas quatro ejaculados, de quatro animais conhecidamente férteis, com idade entre 4 e 8 anos. Após a coleta, o sêmen foi distribuído entre os quatro tratamentos, sendo eles, melatonina, ácido ferúlico, mioinositol e controle, utilizando-se diluidor á base de leite desnatado, na concentração de 25 milhões de espermatozoides por mL. As amostras foram refrigeradas à 5°C, sob uma curva de refrigeração de 0,09°C/min e avaliadas com 0, 4 e 8 horas de refrigeração, quanto às características de motilidade (CASA), integridade das membranas plasmática, acrossomal e o potencial de membrana mitocondrial (utilizando-se as sondas fluorescentes PI, H342, FITC-PSA e JC-1, por microscopia de epifluorescência), e quantificação da produção de espécies reativas de oxigênio (utilizando-se a sonda fluorescente DCFH-DA, por fluorímetria). Os dados obtidos foram analisados pelo programa SAS, versão 9.3 (SAS, 2011). [...] A fluorescência emitida, relativa à quantidade de espécies reativas de oxigênio presentes na amostra não foi alterada pelos tratamentos, em nenhum dos tempos. Com isso conclui-se que a adição de melatonina e ácido ferúlico aumenta a porcentagem de células com alto potencial de mitocôndria, sugerindo a adição desses compostos ao diluidor visando maior manutenção da viabilidade por até 8 horas de refrigeração.

Oxidative stress is detrimental to several sperm characteristics such as motility, plasma, acrosomal and mitochondrial membrane integrity, and can lead to reduced fertility, also in cooled semen. Few studies were performed using melatonin intending an improvement in equine sperm characteristics. Para isso, foram utilizadas quatro ejaculados, de quatro animais conhecidamente férteis, com idade entre 4 e 8 anos. Myoinositol and ferulic acid, in turn, were never used in this species. The objective of the present study was to evaluate the influence of these compounds in equine cooled semen characteristics. Four collections from four stallions of known fertility aged between 4 and 8 years old were used. After collection, semen was distributed in one of the four treatments, melatonin, ferulic acid, myoinositol and control. A skim milk based extender was used and semen was diluted to a final concentration of 25 million sperm per mL. Samples were cooled at 5°C, at a cooling rate of 0.09°C/min and evaluated at 0, 4 and 8 hoours of cooling. CHaracteristics anlyzed were motility (CASA), plasma and acrosomal membrane integrity mytochondrial membrane potential (using florescente probes PI, H342, FITC-PSA e JC-1, using epifluorescence microscopy), and reactive oxygen species production quantification (using DCFH-DA fluorescente probe, by fluorimetry. [...] Percentage of cells with intact acrosomal membrane (IAM) was higher in melatonin treated group (99.69± 0.07) than all the other groups (99.41 ± 0.09; 99.33 ± 0.09; 99.39 ± 0.09; myoinositol, ferulic acid and control, respectively). Concerning reactive oxygen species in the sample, emitted fluorescence was not altered by treatments at any moment evaluated. It can be concluded that the addition of melatonin and ferulic acid the percentage of high mitochondrial potential cells, suggesting a beneficial utilization of these coumpounds in the extender for a greater maintenance of viability up to 8 hours of cooling.

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