Estrus synchronization (ES) is a valuable technology that can help beef cow-calf producers to overcome infertility caused by prolonged anestrus. Protocols for ES that use progesterone (P4) supplementation are of particular value to cows with prolonged postpartum anestrus as P4 triggers them to begin cycling and allows them to have fertility similar to that of cycling cows. Supplementation of P4 intravaginally with the use of a controlled internal drug release device (CIDR) improves cycle induction when compared to oral administration of P4. Vaginitis has been reported as a side effect to CIDR use in cattle, which raises concerns about its downstream effects on fertility. More specifically, the effects of CIDR use on the vaginal environment requires exploration, as no studies have explored the changes in vaginal microbiome in response to CIDR based ES protocols. In cattle, the vaginal microbiome has not been widely explored. On the contrary, the human vaginal microbiome is a well-defined environment, rich in bacteria from the genus Lactobacillus, which are responsible for promoting an environment of acidic pH. The dominance of Lactobacillus in the human vagina, however, fluctuates according to steroid hormone concentrations, and disruptions in the vaginal environment will cause depletion of Lactobacillus species, increase in vaginal pH and decreased fertility. Based on this data in humans, our objectives were to describe incidence of vaginitis caused by the CIDR in beef cows, as well as the vaginal microbiome changes in response to CIDR based protocols, and explore their relation to fertility. We found high incidences of vaginitis caused by CIDR use, yet CIDR-induced vaginitis did not negatively affect pregnancy outcomes. However, at CIDR withdrawal, there was decreased bacterial diversity, increased vaginal pH, increased bacterial abundance, and increased vaginal inflammation when compared to what was observed prior to CIDR insertion. Furthermore, abundance of bacteria, vaginal inflammation, and bacterial diversity, but not vaginal pH, were restored to normal values by the day of timed artificial insemination. This important finding suggests that although the vaginal microbiome was disrupted by the use of CIDR, the vaginal microbiome is resilient and capable of restoring its natural conditions without intervention. Finally, cows that ultimately became pregnant were found to have had increased bacterial diversity and decreased vaginal pH prior to protocol initiation, suggesting that the vaginal microbiome may play a role in individual cow fertility. In conclusion, our results indicate that for beef cows a more diverse vaginal microbiome with decreased vaginal pH presents greater resilience of the microbiome towards disruptions caused by an ES protocol, which is translated in greater pregnancy success. / Doctor of Philosophy / According to the Food and Agriculture Organization, the world population is expected to grow by 51% by the year of 2100. The efficiency of food production must therefore be optimized, given the finite availability of farmable land. In beef production, cow fertility is of great importance, since it will ultimately determine the number of animals available for slaughter. The main reproductive issue that cow-calf producers face is that after calving, cows will undergo a period known as postpartum anestrus, in which cows fail to ovulate. Artificial insemination (AI) can help to optimize beef production efficiency, since it allows for the dispersal of semen from valuable bulls to facilitate the genetic enhancement of herds. The use of estrus synchronization (ES) protocols allows for induction and synchronization of ovulation, which allows AI to be performed at the same time for large groups of cows. Progesterone is often used in ES protocols and is the hormone responsible for inducing cyclicity in postpartum cows. Progesterone can be administered either orally or intravaginally via the use of a controlled internal drug release (CIDR). While the CIDR seems to be more effective at inducing cyclicity of cattle compared to oral progesterone administration, vaginal inflammation as response to the CIDR has been reported in cattle. Little is known about the downstream effects of this inflammation on the normal vaginal microbiota and fertility in cattle. In humans, the vaginal microbiome is predominated by a single genus of bacteria (Lactobacillus), that has an essential role in producing lactic acid, which results in the human vagina being remarkably acidic. In humans, depletion of this bacteria, a condition called bacterial vaginosis (BV), allows for other types of bacteria to grow, which results in an increased vaginal pH and decreased fertility. The bovine vaginal microbiome composition and pH in response to the hormones administered during ES protocols and its relation to fertility have not been widely explored. Our objectives were to document the incidence of vaginitis caused by the CIDR in beef cows and evaluate its effects on the vaginal microbiome changes and fertility. We found high incidences of vaginitis caused by the CIDR, yet no effects of CIDR-induced vaginitis were seen on pregnancy success to the protocol. However, decreased bacterial diversity, followed by increases in vaginal pH, abundance of bacteria and vaginal inflammation are all detected at CIDR withdrawal when compared to before CIDR insertion. Furthermore, abundance of bacteria, vaginal inflammation, and bacterial diversity, but not vaginal pH, were restored to normal values by the day of timed AI, indicating that although the vaginal microbiome was disrupted using CIDR, the vaginal microbiome can restore to natural conditions, and indicate resilience of the vaginal microbiome. Finally, cows that became pregnant to the protocol presented increased bacterial diversity and decreased vaginal pH prior to the protocol. In conclusion, our results indicate that for beef cows a more diverse vaginal microbiome with decreased vaginal pH presents greater resilience of the microbiome towards disruptions caused by an ES protocol, which is translated in greater pregnancy success.

No description available.

No description available.

The objective of these experiments was to determine the effects of and/or interactions among estrous synchronization treatments, reproductive status, and stage of the estrous cycle on estrous response (ER), first service conception rates (CR), pregnancy rates (PR), and embryonic mortality (EM) after 25 d of gestation. Angus or Angus crossbred cattle (n=391) at two locations were assigned to receive either melengestrol acetate for 7 d (MGA-PGF; .5 mg/hd/d, n=136) or progesterone releasing intravaginal device for 7 d (PRID-PGF; n=139) or to serve as untreated controls (n=116). All animals in MGA and PRID treated groups coincidentally received 25 mg prostaglandin F₂α (PGF) on the final day of treatment. Real time, B-mode, ultrasound with a 7.5 mHz linear-array transducer was used to conduct three ovarian scans at 7-d intervals beginning 7 d prior to initiation of treatment. Jugular blood samples were collected at each scanning period. Serum was harvested and stored at 4°C until radioimmunoassayed for progesterone (P4). Serum P4 levels in conjunction with ovarian scans were used to determine cycling status and stage of the estrous cycle at initiation of treatment. Cattle treated with PRID-PGF exhibited a greater synchronized ER (P < .06) than MGA-treated cattle. Cycling animals had a greater ER than noncycling animals, regardless of treatment (P < .01). Anestrous postpartum cows and prepubertal heifers treated with PRID-PGF exhibited a greater ER (P < .05) within 7 d than either MGA-treated or untreated control animals. Conception rates of cattle treated with PRID-PGF beginning late (> Day 16) in the estrous cycle were improved over those of MGA-treated cattle (P < .13) at the same stage. Pregnancy rate at 21 d was higher in PRID-treated cattle than untreated controls (P < .01). Ultrasound scans for embryonic viability were conducted at 25, 45, and 65 d of gestation. Calving data was collected to characterize EM between 65 d and term. The majority of embryonic loss occurring after 25 d of pregnancy occurred before 45 d. Synchronization treatment had no effect on the extent of EM occurring after 25 d of gestation. Embryonic mortality occurring between d 45 and 65 (2%) and between d 65 and term (3%) when combined were similar in magnitude to EM occurring between 25 and 45 d of gestation (4.8%). In conclusion, PRID for 7 d combined with PGF was a superior synchronization treatment for the mixed group of cyclic and anestrous cattle. / Master of Science

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No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) JESSE TURCHIELO GRUNDEMANN.pdf: 787037 bytes, checksum: b8d2b3a0aafb3ac92a7ca1c97f74ec16 (MD5) Previous issue date: 2016-08-18 / Objetivou-se comparar o desempenho reprodutivo de novilhas, vacas solteiras e vacas com cria ao pé submetidas à ressincronização utilizando o protocolo hormonal de inseminação artificial com detecção de estro e em tempo fixo (IAETF). Foram utilizadas 382 fêmeas bovinas das raças Angus e Brangus, sendo 136 novilhas, 103 vacas solteiras e 143 vacas amamentando (entre 40 e 70 dias pós-parto). No dia 0, todos os animais receberam um dispositivo intravaginal contendo 1,2 g de progesterona (para sincronização de vacas adultas) ou reutilizado (para sincronização de novilhas e na ressincronização de novilhas e vacas adultas) e uma injeção intramuscular (IM) contendo 2 mg de benzoato de estradiol (BE). Na tarde do dia 6, os animais receberam injeção contendo (IM) 300 UI de gonadotrofina coriônica equina (eCG) e 0,15 mg de D-cloprostenol e os bezerros tabuleta nasal por 4 dias (até o dia 10). Na tarde do dia 7, os dispositivos vaginais foram removidos e o estro foi monitorado às 24 e 36 horas após a retirada dos dispositivos. Os animais em estro foram inseminados 12 horas mais tarde e o restante recebeu uma injeção (IM) contendo 0,01 mg de Acetato de Buserelina às 48 horas após a retirada dos dispositivos e foram inseminados em tempo fixo (IATF) 12 a 16 horas após a injeção (dia 10). Na sincronização, o percentual de estro diferiu (P < 0,05) entre as três categorias (63,1%, 52.9% e 24,4% para vacas solteiras, novilhas e vacas amamentando, respectivamente). Já na ressincronização, apenas as vacas amamentando demonstraram menor (P < 0,05) percentual de cio (25,0%) quando comparadas às novilhas (82,0%) e vacas solteiras (72,7%). Na primeira IA, as novilhas apresentaram maior (P < 0,05) percentual de prenhez (71,3%) que as vacas amamentando (58,0%), mas 6 ambas as categorias não diferiram (P > 0,05) em relação às vacas solteiras (67,9%). Já na ressincronização, o percentual de prenhez das três categorias não diferiu (P > 0,05) entre si (51,2%; 51,5% e 60,0% para novilhas, vacas solteiras e vacas amamentando, respectivamente). Os percentuais de prenhez cumulativos das duas IAETFs (86,0%; 84,4% e 83,2% para novilhas, vacas solteiras e amamentando, respectivamente) e do final da estação reprodutiva após repasse com touros (94,1%; 91,2% e 87,4% para novilhas, vacas solteiras e amamentando, respectivamente) não diferiram (P > 0,05) entre as três categorias. Conclui-se que novilhas, vacas solteiras e vacas amamentando apresentam desempenho reprodutivo semelhante quando submetidas à ressincronização com IAETF, bem como após o repasse com touros. / The aim of this study was to compare the reproductive performance of heifers, nonlactating and lactating beef cows submitted to fixed time and estrus detection artificial insemination hormonal protocol (FTEAI). A total of 382 bovine females divided in 136 heifers, 103 nonlactating and 143 lactating cows (between 40 and 70 days postpartum) were used. On day 0 all animals received an intravaginal device containing 1.2g of progesterone (used on adult cows) or reutilized (used on heifers synchronization and on heifers and adult cows resynchronization) and an injection (IM) containing 2 mg of estradiol benzoate (EB). In the afternoon of day 6, animals received an injection (IM) containing 300 IU of equine chorionic gonadotropin (eCG) and 0.15 mg of D-cloprostenol and calves a no se tablet for 4 days (until day 10). In the afternoon of day 7, intravaginal devices were removed and estrus was monitored at 24 and 36 h after device removal. Animals detected in estrus were artidicial insemination (AI) 12 h later and the remaining received an injection (IM) containing 0.01mg of Busereline Acetate at 48 h after device removal and were submitted to timed artificial insemination (TAI) 12 to 16 h after the injection (Day 10). In the synchronization, estrus rate differ (P < 0.05) among the three categories (63.1%, 52.9% and 24.4% to nonlactating cows, heifers, and lactating cows, respectively). Where as in resynchronization, only lactating cows showed lower (P < 0.05) estrus rate (25.0%) when compared for heifers (82.0%) and nonlactating cows (72.7%). In the synchronization heifers showed higher (P < 0.05) pregnancy rate (71.3%) than lactating cows (58.0%), but both categories did not differ (P > 0.05) in relation to nonlactating cows (67.9%). In resynchronization, pregnancy rate of three 8 categories did not differ betwem (P > 0.05) each other (51.2%, 51.5% and 60.0% for heifers, nonlactating cows and lactating cows, respectively). The cumulative pregnancy rates from two FTEAI (86.0%, 84.4% and 83.2% for heifers, nonlactating and lactating cows, respectively) and from final reproductive season after breeding with bulls (94.1%, 91.2% and 87.4% to heifers, nonlactating and lactating cows, respectively) did not differ (P > 0.05) among the categories. In conclusion, heifers, nonlactating and lactating cows show similar reproductive performance at the end of breeding season when submitted to resynchronization using FTEAI, as well as after a short-term breeding with bulls.

A espécie equina apresenta algumas peculiaridades em relação às demais espécies por apresentar baixa taxa de fertilidade. É importante que a égua conceba logo após o parto para que possa gerar um produto por ano. Na fêmea equina, o primeiro cio pós-parto geralmente acontece 5 a 15 dias após o nascimento do produto. No Brasil, a prática da utilização do cio do potro não é frequente, existindo ainda entre os veterinários, a adoção de diferentes protocolos. Além disso, no Sul do Brasil encontramos grandes criatórios de cavalos Puro Sangue De Corrida (PSC) e de cavalos Crioulos, o que diferencia ainda mais as técnicas adotadas pelos profissionais. O presente estudo visa analisar a fertilidade do primeiro e do segundo cio pós-parto e a incidência de perdas gestacionais, em éguas da raça Crioula e PSC. O trabalho foi realizado em dois criatórios de equinos da raça PSC e em dois criatórios de equinos da raça crioula localizados na região sul do Estado do Rio Grande do Sul, durante a temporada reprodutiva de 2015. Ao todo, foram avaliadas 209 éguas paridas com idade entre 5 e 26 anos, sendo destas 105 PSC e 104 da raça Crioula. Estas foram distribuídas em dois grupos conforme a raça e subdivididas conforme a idade, com menos de 12 anos e com mais de 12 anos. O controle folicular foi realizado através de palpação retal e ultrassonografia e foram utilizados diferentes garanhões com fertilidade provada. O diagnóstico de gestação era realizado com 14 dias após a ovulação e a prenhez foi reavaliada até 60 dias para avaliar supostas perdas gestacionais A análise do Teste de Qui- Quadrado foi utilizada para avaliar a taxa de prenhez em cada grupo. Na primeira análise do trabalho as raças foram separadas e os resultados do primeiro e do segundo cio foram comparados, não foi identificada diferença estatística entre o primeiro e o segundo cio nas duas raças e além disso, as perdas gestacionais foram similares. Em uma segunda análise, foi comparado o uso do cio do potro considerando as faixas etárias dentro de cada raça. O resultado da taxa de prenhez da raça PSC foi de 61,54% de prenhez em éguas com menos de 12 anos e 50% em éguas com 12 anos ou mais, que não identificou diferença. Já nas éguas Crioulas a diferença foi maior, sendo que as éguas com menos de 12 anos apresentaram 96,55% de taxa de prenhez e as éguas com 12 anos ou mais a taxa de prenhez foi de 39,13% que identificou diferença. As mesmas análises foram feitas para o segundo cio após o parto, na raça PSC, não identificou diferença nos resultados de éguas mais jovens e mais velhas. Já nas éguas Crioulas foi identificado diferença É importante destacar, que as éguas Crioulas não foram submetidas à vulvoplastias e nem à lavagens uterinas, já as éguas da raca PSC foram submetidas quando necessário. Em conclusão, o fator idade é importante considerar e especialmente avaliar os cuidados necessários, uma vez que o aumento da idade está associado com a redução da competência reprodutiva; o cio do potro apresenta fertilidade semelhante aos demais cios e traz como vantagem garantir a produção de um produto por ano, visando a produção de animais bem-nascidos. / The equine species presents some peculiarities in relation to the other species due to the low fertility rate. It is important that the mare conceives soon after delivery so that she can generate one product per year. In the equine female, the first postpartum estrus usually occurs 5 to 15 days after the birth of the product. In Brazil, the practice of using foal cio is not frequent, and there are still different protocols among veterinarians. In addition, in southern Brazil we find large breeders of purebred racing horses (PSC) and criollo horses, which further differentiates the techniques adopted by professionals. The present study aims to analyze the fertility of the first and second postpartum estrus and the incidence of gestational losses in Crioula and PSC mares.The work was carried out in two breeders of PSC horses and two Crioulo horses breeders located in the southern region of the State of Rio Grande do Sul, during a breeding season of 2015. Altogether, 209 mares born with age between 5 and 26 years, being these 105 PSC and 104 of the breed Crioula. These were divided into two groups according to race and subdivided according to age, less than 12 years and over 12 years. Follicular control was performed through rectal palpation and ultrasonography and used different stallions with proven fertility. The diagnosis of gestation was performed 14 days after an ovulation and a preparation for reassessment up to 60 days to evaluate alleged gestational losses An analysis of the Quadrilateral Test was used to evaluate the pregnancy rate in each group. In the first analysis of the work as breeds were separated and the results of the first and second estrus were compared, no statistical difference was identified between the first and second estrus in both breeds and furthermore as gestational losses. In a second analysis, the use of foal heat was considered among age groups within each race. The result of the PSC pregnancy rate was 61.54% pregnant in mares aged less than 12 years and 50% in mares aged 12 years or more, which did not identify differences. In Mares Crioulas the difference was greater, and as mares with less than 12 years presented 96.55% of pregnancy rate and as mares with 12 years or more the pregnancy rate was 39.13%, which identified a difference. As a summary is made, make sure that there is no identification, it is not identified in the results of younger and older mares. Already in the mares Creoles was identified difference. It is important to emphasize that, as Crioulas mares were not subjected to vulvoplasty or uterine lavage, they were already submitted as needed. In conclusion, the age factor is important to consider and especially to evaluate the necessary care, since the increase of the age is associated with a reduction of the reproductive competence; the horse's foal presents fertility and production of products per year, aiming at a production of well-born animals.

Abstract not available

Transrectal ovarian ultrasonography and hormone measurements were used to study ovarian antral follicular dynamics and development of luteal structures during the middle portion of the breeding season in non-prolific cross-bred Western white-faced ewes and prolific Finn sheep. Studies were also done on ovarian activity in Western white-faced ewes during the transition to seasonal anoestrus and at the onset of the breeding season. Lastly, two experiments were carried out to examine ovulatory responses and subsequent luteal function in Western white-faced ewes treated with luteolysin (PgF 2á) and progestogen (medroxyprogesterone acetate-MAP) during the luteal phase of the oestrous cycle and after ovulation induction with gonadotrophin-releasing hormone (GnRH) in mid-anoestrus. The results of the present experiments showed that the growth of ovine antral follicles reaching ovulatory sizes of >=5 mm in diameter occurred in a wave-like pattern throughout the oestrous cycle in both breeds of sheep under study. There were typically 3 or 4 waves of follicle production throughout the 17-day interovulatory period. Ovarian follicular emergence, or beginning of growth from the pool of 3-mm follicles, appeared to be primarily controlled by changes in circulating concentrations of follicle-stimulating hormone (FSH). In cyclic ewes, the largest ovarian follicles acquired the ability to secrete oestradiol from the day of emergence and a peak of oestradiol secretion occurred about the time they reached their maximum diameter. The high ovulation rate in prolific Finn sheep appeared to be achieved mainly by the ovulation of follicles emerging in the last two waves of the interovulatory interval. Interestingly, prolific Finn ewes produced more but smaller corpora lutea (CL) and had lower serum concentrations of progesterone during the luteal phase of the oestrous cycle as compared to non-prolific Western white-faced ewes. During the transition into seasonal anoestrus in Western white-faced ewes, FSH secretion resembled that during the breeding season but the pattern of emergence of sequential follicular waves was dissociated from FSH and oestradiol secretion. Prior to the first ovulation of the breeding season, there was a distinct elevation in circulating concentrations of progesterone produced by luteinized unovulated follicles and/or interstitial tissue of unknown origin. This increase in serum levels of progesterone, heralding the resumption of ovulatory cycles, did not alter the rhythmic pattern FSH secretion or follicular wave emergence. Treatment of non-prolific Western white-faced ewes with PgF2á and MAP applied late in the oestrous cycle changed follicular dynamics and increased ovulation rate to resemble that in prolific Finn sheep. Effects of MAP on the recruitment and growth of ovulatory follicles in Western white-faced ewes did not have a clear gonadotrophic dependancy, suggesting a possible local regulation of ovarian activity by progestins in ewes. Following the induction of ovulation with GnRH in anoestrous Western white-faced ewes, an array of ovarian responses were detected with ultrasonography, including failure of ovulation of large antral follicles, normal (fall-lifespan) and short-lived CL post-ovulation, and luteinized cystic-like follicles. The normal luteinization of ovulated follicles appeared to be related to the amplitude of episodic elevations in daily serum FSH concentrations before induction of ovulation and characteristics of the preovulatory LH surge.

A espécie equina apresenta algumas peculiaridades em relação às demais espécies por apresentar baixa taxa de fertilidade. É importante que a égua conceba logo após o parto para que possa gerar um produto por ano. Na fêmea equina, o primeiro cio pós-parto geralmente acontece 5 a 15 dias após o nascimento do produto. No Brasil, a prática da utilização do cio do potro não é frequente, existindo ainda entre os veterinários, a adoção de diferentes protocolos. Além disso, no Sul do Brasil encontramos grandes criatórios de cavalos Puro Sangue De Corrida (PSC) e de cavalos Crioulos, o que diferencia ainda mais as técnicas adotadas pelos profissionais. O presente estudo visa analisar a fertilidade do primeiro e do segundo cio pós-parto e a incidência de perdas gestacionais, em éguas da raça Crioula e PSC. O trabalho foi realizado em dois criatórios de equinos da raça PSC e em dois criatórios de equinos da raça crioula localizados na região sul do Estado do Rio Grande do Sul, durante a temporada reprodutiva de 2015. Ao todo, foram avaliadas 209 éguas paridas com idade entre 5 e 26 anos, sendo destas 105 PSC e 104 da raça Crioula. Estas foram distribuídas em dois grupos conforme a raça e subdivididas conforme a idade, com menos de 12 anos e com mais de 12 anos. O controle folicular foi realizado através de palpação retal e ultrassonografia e foram utilizados diferentes garanhões com fertilidade provada. O diagnóstico de gestação era realizado com 14 dias após a ovulação e a prenhez foi reavaliada até 60 dias para avaliar supostas perdas gestacionais A análise do Teste de Qui- Quadrado foi utilizada para avaliar a taxa de prenhez em cada grupo. Na primeira análise do trabalho as raças foram separadas e os resultados do primeiro e do segundo cio foram comparados, não foi identificada diferença estatística entre o primeiro e o segundo cio nas duas raças e além disso, as perdas gestacionais foram similares. Em uma segunda análise, foi comparado o uso do cio do potro considerando as faixas etárias dentro de cada raça. O resultado da taxa de prenhez da raça PSC foi de 61,54% de prenhez em éguas com menos de 12 anos e 50% em éguas com 12 anos ou mais, que não identificou diferença. Já nas éguas Crioulas a diferença foi maior, sendo que as éguas com menos de 12 anos apresentaram 96,55% de taxa de prenhez e as éguas com 12 anos ou mais a taxa de prenhez foi de 39,13% que identificou diferença. As mesmas análises foram feitas para o segundo cio após o parto, na raça PSC, não identificou diferença nos resultados de éguas mais jovens e mais velhas. Já nas éguas Crioulas foi identificado diferença É importante destacar, que as éguas Crioulas não foram submetidas à vulvoplastias e nem à lavagens uterinas, já as éguas da raca PSC foram submetidas quando necessário. Em conclusão, o fator idade é importante considerar e especialmente avaliar os cuidados necessários, uma vez que o aumento da idade está associado com a redução da competência reprodutiva; o cio do potro apresenta fertilidade semelhante aos demais cios e traz como vantagem garantir a produção de um produto por ano, visando a produção de animais bem-nascidos. / The equine species presents some peculiarities in relation to the other species due to the low fertility rate. It is important that the mare conceives soon after delivery so that she can generate one product per year. In the equine female, the first postpartum estrus usually occurs 5 to 15 days after the birth of the product. In Brazil, the practice of using foal cio is not frequent, and there are still different protocols among veterinarians. In addition, in southern Brazil we find large breeders of purebred racing horses (PSC) and criollo horses, which further differentiates the techniques adopted by professionals. The present study aims to analyze the fertility of the first and second postpartum estrus and the incidence of gestational losses in Crioula and PSC mares.The work was carried out in two breeders of PSC horses and two Crioulo horses breeders located in the southern region of the State of Rio Grande do Sul, during a breeding season of 2015. Altogether, 209 mares born with age between 5 and 26 years, being these 105 PSC and 104 of the breed Crioula. These were divided into two groups according to race and subdivided according to age, less than 12 years and over 12 years. Follicular control was performed through rectal palpation and ultrasonography and used different stallions with proven fertility. The diagnosis of gestation was performed 14 days after an ovulation and a preparation for reassessment up to 60 days to evaluate alleged gestational losses An analysis of the Quadrilateral Test was used to evaluate the pregnancy rate in each group. In the first analysis of the work as breeds were separated and the results of the first and second estrus were compared, no statistical difference was identified between the first and second estrus in both breeds and furthermore as gestational losses. In a second analysis, the use of foal heat was considered among age groups within each race. The result of the PSC pregnancy rate was 61.54% pregnant in mares aged less than 12 years and 50% in mares aged 12 years or more, which did not identify differences. In Mares Crioulas the difference was greater, and as mares with less than 12 years presented 96.55% of pregnancy rate and as mares with 12 years or more the pregnancy rate was 39.13%, which identified a difference. As a summary is made, make sure that there is no identification, it is not identified in the results of younger and older mares. Already in the mares Creoles was identified difference. It is important to emphasize that, as Crioulas mares were not subjected to vulvoplasty or uterine lavage, they were already submitted as needed. In conclusion, the age factor is important to consider and especially to evaluate the necessary care, since the increase of the age is associated with a reduction of the reproductive competence; the horse's foal presents fertility and production of products per year, aiming at a production of well-born animals.

A morfologia e a fisiologia ovariana nos equinos têm sido motivo de estudo devido a seu córtex e medula invertidos em comparação às das outras espécies mamíferas e seu ciclo reprodutivo fotoperíodo-dependente e à existência de uma fossa de ovulação. Estes aspectos levam ao profissional do campo da reprodução equina a se interessar em aprofundar cada vez mais no desenvolvimento de pesquisas que possam auxiliar oferecendo métodos e técnicas que ajudem no trabalho de campo. Uma das melhores técnicas utilizadas para o estudo da atividade ovariana têm sido as imagens ultrassonográficas nos seus diferentes modos de operação. Uma das estruturas ovarianas que se pode avaliar e acompanhar com o ultrassom é o Corpo Lúteo (CL), sendo ele vital pela produção de Progesterona (P4), hormônio encarregado da preparação do endométrio para oferecer um ambiente ao embrião. É relatada uma relação positiva entre quantidade de células lúteas e produção de P4. O objetivo deste estudo foi testar uma metodologia que permitisse avaliar a densidade celular por meio da histologia e determinar se existe relação com o numero de pixéis lúteos numa imagem de ultrassom e assim ter um dado confiável para tomar decisões. Foram coletados 29 ovários de éguas crioulas em diferentes fases do diestro, analisados todos dentro de um único grupo. As amostras foram passadas pelo ultrassom para obter a imagem ultrasonográfica salva diretamente do ultrassom. Posteriormente, os CLs foram dessecados para fazer laminas corada pela Hematoxilina Eosina. Os resultados mostraram que entre as variáveis existe correlação inversa de R=-0.61. O coeficiente de determinação achado foi de aproximadamente R2=40% com uma probabilidade P=0.04%. Os resultados indicam que, existem variações no numero de pixéis lúteos que podem explicar em grande percentagem os valores totais do numero de células presentes no tecido lúteo. / The ovarian morphology and physiology in horses has been the subject of study due to its reversed cortex and medulla in comparison to other mammalian species, the existance of an ovulation fossa and for its photoperiod-dependent reproductive cycle. These aspects lead to the field practitioner specialist on equine to develop research that may help at fieldwork. One of the best techniques for the study of ovarian activity has been the ultrassonographic images in its different modes of operation. The corpus luteum (CL) is one of the ovarian structures that can be assessed and followed by ultrasound, being vital for the production of progesterone (P4), hormone which prepares the endometrium to provide a good environment for embryo development. A positive relationship between amount of luteal cells and P4 production has been reported before. The aim of this study was to test a methodology that would assess cell density by histology and determine whether there is a correlation between the number of ultrasound image pixels and the luteal cells concentration and thus have a really trusted ultrasound data which might help veterinarians to make decisions. Twenty nine ovaries from criollo mares were collected at different stages of diestrus, and all analyzed within a unique group. Samples were assessed by ultrasound to obtain the ultrasonographic image. After that, the CLs were dried to make microscopy slides stained with hematoxylin-eosin. The results showed that an inverse correlation (r = -0.61) exists between the variables studied. The determination coefficient found was approximately R2 = 40% with a probability of P = 0.04%. The results indicate that there are variations in the number of pixels that can explain differences in the numbers of luteal cells in the corpus luteum tissue.