Abstract This study aimed to evaluate the effect of synchronization with prostaglandin F2α in Baixadeiro mares during the rainy and dry seasons. Fourteen mares were synchronized by administering two doses of 1 mL prostaglandin PGF 2α and monitored by rectal palpation and ultrasound for the assessment of follicular development and uterine echotexture. Of this total, nine mares allowed the collection of blood, in which the blood was collected by venipuncture of the jugular vein to determine progesterone (P4) by ELISA. Mares showed no differences (P > 0.05) in weight, body score condition (BSC), tone, uterine edema, frequency of ovulation, synchronization interval, estrus, and the total number of follicles between periods. However, there was a difference in large increased follicle diameter (P < 0.05) during the dry season. The average concentrations of P4 in mares differed (P < 0.05) between the pre- and post-ovulatory phases for both seasons and after ovulation, with higher concentrations in the rainy season. Furthermore, statistical differences in daily light (P < 0.05) were observed between the dry and rainy periods. Thus, we conclude that mares from the genetic grouping Baixadeiro showed no reproductive seasonality, though there was a difference in luminosity between the rainy and dry seasons. The treatment with two doses of PGF 2α was effective in synchronizing the mares, promoting the return of estrus in the dry and rainy periods. The mares remaining cyclically active throughout the year provided there were appropriate forage availability and quality levels to allow for normal values of body weight and condition.

RESUMO: As desordens no equilíbrio ácido base são comuns em equinos após exercício intenso. Exercícios de alta intensidade e curta duração ocasionam frequentemente acidose metabólica. Entender as alterações neste equilíbrio é essencial para instituir programas de treinamentos que visam melhorar o condicionamento físico dos equinos atletas, minimizando alterações na homeostasia. O estudo avaliou o efeito do treinamento de três tambores sobre o equilíbrio ácido base em equinos. A avaliação foi realizada nos seguintes tempos: T0 - imediatamente antes do início do treinamento; T1 - imediatamente após o fim do segundo percurso de treinamento; T2 - uma hora após o fim do segundo percurso. Em T1, ocorreu diminuição (P<0,05) nos valores do pH, HCO3 -, pCO2, cBase, tCO2 e diferença de íons fortes, enquanto o lactato e o ânion gap aumentaram (P<0,05). Conclui-se que o treinamento de três tambores causou acidose metabólica passageira nos equinos, sendo que a hiperlactatemia ainda permaneceu manifestada após uma hora de descanso.

ABSTRACT: In horses, acid-base balance disorders are common after intense exercise, with metabolic acidosis being the most common after high intensity and short duration exercise. Understanding the processes that cause them is fundamental for procedures, which aimed to improve the physical fitness of horses for athletic purposes, with fewer changes in homeostasis. The present study assessed the effect of barrel racing on acid base balance in Quarter Horse, at the following times: T0 - immediately before training; T1 - immediately after the end of the second course; T2 - one hour after the end of the second course. In T1, there was decrease (P<0.05) in the pH, HCO3 -, pCO2, cBase, tCO2 and strong ion difference concentrations, while the plasma lactate and anion gap increased (P<0.05). It was concluded that barrel racing training caused transient metabolic acidosis in the horses, and hyperlactatemia was still present after an hour of rest.

RESUMO Objetivou-se avaliar os efeitos da melatonina na produção in vitro de embriões bovinos. O experimento foi conduzido no Laboratório de Reprodução Animal da Universidade Estadual do Maranhão. Os complexos cumulus-oócitos (CCOs) foram distribuídos entre os tratamentos 0, 10-1, 10-3 e 10-5 µmol/L de melatonina. A avaliação foi dividida em dois experimentos, onde o primeiro avaliou o efeito dessas diferentes concentrações de melatonina (tratamentos) sobre a taxa de maturação dos CCOs e o segundo, o efeito desses tratamentos com melatonina sobre a produção in vitro de embriões bovinos. Os resultados no primeiro experimento demonstraram não haver diferença significativa na taxa de maturação in vitro dos CCOs cultivados no tratamento com melatonina. No entanto, o tratamento com melatonina no segundo experimento, as taxas de clivagens, mórulas e blastocistos, o grupo 10-5 µM foi estatisticamente superior (52,9%, 52,9% e 35,3%, respectivamente) e o grupo 10-1 µM inferior (19,5%, 19,5% e 7,8%, respectivamente) aos outros grupos. O grupo controle (sem melatonina) e o grupo 10-3 µM obtiveram resultados semelhantes. Concluiu-se que a suplementação da melatonina no meio de maturação in vitro não evidenciou melhoras na taxa de maturação dos oócitos, porém na produção in vitro de embriões em diferentes concentrações, o grupo 10-5 µM apresentou melhores resultados mesmo não havendo melhorias nas variáveis (P<0,05).

ABSTRACT We aimed to assess the effects of melatonin in the in vitro production of bovine embryos. Our experiment was conducted at the Laboratório de Reprodução Animal of the Universidade Estadual do Maranhão. The cumulus-oocyte complexes (COCs) were distributed among treatments at concentrations of 0, 10-1, 10-3 and 10-5 µMol/L melatonin. Our experiment was further divided into two: the first was to assess the effect of different concentrations of melatonin (treatments) on the maturation rate of COCs, and the second was to assess the effects of melatonin treatments on the in vitro production of bovine embryos. The results from the first experiment demonstrated no significant difference between the in vitro maturation rate of the cultivated COCs in treatments with melatonin. In the second experiment, however, melatonin treatments yielded statistically higher cleavage, morula and blastocyst rates in the 10-5 µM group (52.9%, 52.9%, and 35.3%, respectively), and lower rates in the 10-1 µM group (19.5%, 19.5% and 7.8%, respectively), compared to the others. The control group (no melatonin) and the 10-3 µM group showed similar results. We concluded that supplementation of melatonin in the in vitro maturation medium resulted in no improvement in the oocyte maturation rate, but in the in vitro production of embryos at different concentrations, the 10-5 µM group displayed better results, but with no improvement in the variables (P < 0.05).