Electrocardiographic Aspects of Singleton Pregnancy and Neonatal Period in American Miniature Horse Breed

Background: During pregnancy, cardiovascular adaptations occur in order to meet maternal demands and adequate support for fetal development, but they are still unclear in the equine species, especially in the American Miniature horse breed. The main hemodynamic changes that occur during pregnancy are increased heart rate, cardiac output, and blood volume. It is necessary to use the reference values for the miniature breeds, in addition to the age range and reproductive condition, so the objective of this study was to evaluate the effect of pregnancy on electrocardiographic (ECG) parameters in mares and also of age in newborns foals of American Miniature horse breed. Materials, Methods & Results: Ten American Miniature Horse mares, between 7 and 19 years old (12.14 ± 4.05 years), 116.85 ± 24.09 kg of body weight were used in the experiment. All these mares were pluriparous, with 5.9 ± 3.5 of births, minimum of 2, and maximum of 12 foaling times. They were maintained in common social group in an indoor house stable with straw bed, with access to an outdoor paddock for several h per day. Twice a day they were fed with hay. Mineral supplements and water were available ad libitum. The ECG were obtained in 10 pregnant mares and in 10 neonates. All females were examined at a representative time of each trimester of pregnancy, at 30, 210, 300 days before and 21 days after delivery. Neonates were examined on different times: first 24 h after delivery, weekly on the 7th, 14th, 21st, 28th and 35th days of age. The ECG parameters considered were the heart rate and rhythm, duration and intervals (P, PR, QRS, QT, T) and amplitude (P, R, S, T) of ECG waves. The mean of pregnancy duration was 319.4 ± 4.97 days. Heart Rate (HR) varied between 51 to 59 bpm during pregnancy and 56 bpm on the 21st day after delivery. Comparing the clinical parameters of pregnant mares, non-pregnant mares and foal a difference was found for HR, Respiration Rate (RR) and Temperature (P = 0.001). All ECG parameters of pregnant, non-pregnant and foal mares showed a significant difference (P = 0.0001), except for the amplitude of the P1, P2 and R waves, which was similar for the 3 groups. The mean values of HR and amplitude of the positive T wave were higher in foals when compared to pregnant and non-pregnant mares, which in turn did not differ from each other. The mean duration of the P wave, PR segment, QRS complex, QT segment and T wave were the same among mares and greater than in foals. Comparing pregnant and non-pregnant mares, there was a difference in only 3 parameters: duration of the QTc segment, amplitude of the S wave and negative T wave. The non-pregnant mares had a longer duration of the QTc segment and a greater amplitude of the negative T wave, while the foals had a greater amplitude of the S wave.Discussion: Although this study did not measure HR at delivery time, it is worth to consider the action of the parasympathetic autonomic nervous system close to delivery, which reduces the HR of mares. This is because at delivery, sympathetic-adrenal activation should be avoided since the increase in sympathetic tone can cause uterine atony via B2 receptors. For this reason, it has been shown that, during physiological birth, horses are under parasympathetic control, and stress response mechanisms are not activated. It was conclude that the morphometry of the waves, intervals and ECG complexes, during the evolution of the reproductive state, the electrocardiographic aspects were generally associated with heart rate (PR and QT intervals). As for neonates, there was a discrepancy among the most of ECG parameters when compared to the adult female, regardless of reproductive status, clarifying the importance of ECG patterns not only for the breed, but also for the age group

Estudo clínico e anatomopatológico da urolitíase em cordeiros confinados submetidos à dieta com diferentes concentrações de fósforo

A urolitíase obstrutiva é frequente na ovinocultura e possui etiologia multifatorial, porém o manejo nutricional inadequado é considerado o mais relevante para sua ocorrência. Os objetivos deste estudo foram verificar a influência de duas dietas com diferentes proporções e concentrações de cálcio (Ca) e fósforo (P) no desenvolvimento da urolitíase obstrutiva, e descrever os achados clínicos e anatomopatológicos do sistema urinário de ovinos. Utilizaram-se 30 cordeiros, machos, mestiços das raças Santa Inês e Ile de France, que foram aleatoriamente distribuídos em dois grupos: Grupo 1 (G1, n=15) – Ca:P de 1,9:1 e 0,42% de P; Grupo 2 (G2, n=15) – Ca:P de 1,5:1 e 0,65% de P. As dietas foram fornecidas por 90 dias consecutivos com feno de Coast-cross, farelo de soja, trigo e milho, e água ad libitum. Após o diagnóstico da doença, os cordeiros foram submetidos ao tratamento clínico e cirúrgico, quando necessário. A urolitíase foi detectada em 36,7% (11/30) dos cordeiros, sendo 26,7% assintomáticos e 10% (3/30) apresentaram obstrução uretral. Um cordeiro foi desobstruído após amputação do processo uretral e sondagem uretral; outro foi a óbito por ruptura vesical e uroperitôneo; outro foi sacrificado após uretrostomia perineal e cistostomia sem sucesso. Em ambos os grupos, as alterações histopatológicas renais mais frequentes foram congestão vascular, dilatação e degeneração tubular. A presença de proteínas na luz tubular foi mais pronunciada no G2. As dietas fornecidas, ricas em concentrado, embora com relação Ca:P adequadas, provocaram a calculogênese, o que comprovou que o excesso de minerais e pouca quantidade de volumoso podem causar a enfermidade no rebanho. Palavras-chave: cálculo, confinamento, fósforo, obstrução uretral, ovinos.

Implicações fisiológicas, respostas celulares e desempenho lactacional de cabras Saanen em estresse térmico

The exposure to heat can adversely affect animal performance and productivity, particularly when associated with pregnancy. The comprehension of the physiological and cellular responses during heat stress assists the decisions to improve the productivity of goats in a tropical environment. In this context, this study evaluated the physiological and cellular responses of Saanen goats in acute and chronic stress conditions. Healthy Saanen goats were randomly assigned to heat stress treatment, short-term, under solar radiation and in the long-term, in climatic chamber. Data were analyzed using the Statistical Analysis System (SAS). The normality was confirmed using the Shapiro-Wilk test. In acute heat stress, solar radiation caused the increase of cortisol release, respiratory rate and reduced T3 and T4 to restore homeothermia. The expression of p53 (pro-apoptotic protein), Bcl-2 (anti-apoptotic protein), HSP60, HSP70 and HSP90 was higher in leukocyte cells for heat stressed goats. In chronic heat stress at the end of gestation, goats significantly mobilized the increase of respiratory rate to lose heat, with cortisol elevation on the 15 days previous to parturition (P < 0.05), which was even greater at day 15 postparturition. At the cellular level, HSP70 was the most expressed during and after heat challenge, with more transcripts at day 15 postparturition for the heat stressed goats. In mammary epithelial cells, there were an increase in apoptosis-related transcripts, p53 and Bax, for the group undergoing heat stress before parturition. The expression of HSP27 was higher before and after parturition for the same group when compared to the animals in thermal neutrality. During lactation, the stressed goats presented lower milk yield. The heat challenge increased the percentage of fat and decreased lactose. The somatic cell count was higher for stressed goats during all lactation. During lactation, the gene expression of prolactin receptor (PRLr) was lower for heat stress goats, which may explain the reduction in milk production at subsequent lactation. In conclusion, our findings suggest that respiratory rate and HSP70 are reliable biomarkers for assessing the thermal comfort and thermotolerance of Saanen goats under acute and chronic heat stress. In addition, chronic thermal stress at final gestation impaired milk production and milk composition from subsequent lactation.A exposição ao calor pode afetar negativamente o desempenho e a produtividade dos animais, particularmente quando associados à gestação. Compreender as relações entre as respostas fisiológicas e celulares, quando em estresse por calor, auxilia na tomada de decisões para melhorar a produtividade de caprinos em ambiente tropical. Neste contexto, este estudo avaliou as respostas fisiológicas e celulares de cabras Saanen em condição de estresse agudo e crônico. Cabras da raça Saanen saudáveis foram aleatoriamente expostas ao estresse por calor, de curto prazo sob radiação solar e a longo prazo em câmara climática. Os dados foram analizados utilizando o software estatístico \"Statistical Analysis System\" (SAS, 2008). A normalidade foi confirmada com o teste de Shapiro-Wilk. Em estresse agudo, a radiação solar promoveu o aumento da liberação de cortisol, elevou a frequência respiratória e reduziu T3 e T4, para reestabelecer a homeotermia. Observou-se nas células leucocitárias das cabras sob estresse, aumento da expressão da p53 (proteína pró-apoptótica), Bcl-2 (proteína anti-apoptótica), HSP60, HSP70 e HSP90. Sob estresse crônico no final da gestação, as cabras aumentaram a frequência respiratória para perder calor, com elevação do cortisol no dia 15 pré-parto (P <0,05), que foi ainda maior no dia 15 pós-parto. A nível celular, a HSP70 foi a mais expressa durante e após o desafio com calor, com mais transcritos no dia 15 pós-parto para as cabras sob estresse. Nas células epiteliais mamárias, houve aumento dos transcritos relacionados à apoptose, p53 e Bax, para o grupo sob estresse por calor antes do parto. A expressão da HSP27 foi maior antes e após o parto para o mesmo grupo quando comparado aos animais em termoneutralidade. Durante a lactação, as cabras sob estresse apresentaram menor produção de leite. O desafio de calor aumentou o percentual de gordura e diminuiu a lactose. A contagem de células somáticas foi maior para as cabras sob estresse durante toda a lactação. A expressão gênica do receptor de prolactina (PRLr) foi menor para as cabras sob estresse, 15 dias após o parto, o que pode explicar a redução na produção de leite na lactação subsequente. Em conclusão, nossos achados sugerem que a frequência respiratória e a HSP70 são biomarcadores confiáveis para avaliar o conforto térmico e a termotolerância de cabras Saanen sob estresse por calor agudo e crônico. Além disso, o estresse por calor crônico pré-parto prejudicou a produção e a composição do leite da lactação subsequente

Gene expression of heat shock proteins as molecular marker of thermotolerance in Nellore cows

Objetivou-se com este estudo compreender as dinâmicas das temperaturas corporais em fêmeas da raça Nelore, e relacionar os aspectos fisiológicos da termorregulação com as respostas celulares pela expressão de proteínas de choque térmico. O projeto foi desenvolvido no Laboratório de Biometeorologia e Etologia, da Faculdade de Zootecnia e Engenharia de Alimentos da Universidade de São Paulo, Pirassununga-SP. Foram utilizadas 20 vacas Nelore pluríparas, cíclicas, mantidas em sistema de pastejo. O período experimental precedeu a estação de monta de 2013 e terminou na inseminação artificial. Para classificar os animais quanto ao gerenciamento de calor foi monitorada a temperatura vaginal durante seis dias por meio de 16 data loggers (n=16). Com o intuito de melhor compreender o gerenciamento de calor, outras respostas fisiológicas, nomeadamente temperatura retal, caudal, ocular, frequência respiratória e taxa de sudação foram colhidas durante os quatro dias finais do monitoramento da temperatura vaginal. Para expressão gênica relativa colheram-se amostras de sangue (n=20). Foram realizados choques térmicos in vitro a 38ºC, 40ºC e 42ºC por duas horas. Após tratamento térmico obteve-se o pellet de leucócitos para posterior extração do RNA pelo método TRIzol. Foram escolhidas 10 vacas com os melhores resultados de concentração de RNA, 5 pertencentes ao grupo de vacas eficientes quanto ao gerenciamento de calor, e 5 não eficientes (n=10). A RT-PCR foi realizada com o kit SuperScript III. A reação polimerase em cadeia em tempo real (qPCR) ocorreu no aparelho StepOnePlus® Applied Biosystem utilizando como marcador fluorescente o SYBR® Green para os genes alvo validados HSPA1A, HSPD1, HSP90AA1, HIF1A e endógenos ACTB, RPL15 e PPIA. Os dados foram analisados por ANOVA, regressão e correlação do SAS 9.2. As vacas foram classificadas em eficientes e não eficientes por meio de coeficientes angulares, advindos da regressão das temperaturas vaginais durante períodos de ganho e perda de calor. As vacas eficientes apresentaram menores temperaturas retais 37,65ºC (P<0,01) e maior taxa de sudação 528,73 g. m-². h-¹ (P<0,06). A nível celular, o aumento programado in vitro da temperatura não aumentou quantidade de transcritos, promovendo manutenção à 38ºC e 40ºC e declínio à 42ºC. A ordem decrescente da abundância de transcritos foi HSPA1A, HSPD1 e HSP90AA1. Pode-se concluir que vacas Nelore com diferentes gerenciamentos de calor apresentam respostas termorregulatórias diferentes. A HSPA1A apresentou a maior abundância de transcritos sendo considerada como marcador molecular para termotolerância, por ser a mais sensível à temperatura e bem conservada. Não foi observado diferença nas expressões gênicas relativas das proteínas de choque térmico entre os animais classificados quanto ao gerenciamento de calor.The aim of this study was to understand the dynamics of body temperatures in Nellore females, and relate the physiological aspects of thermoregulation with cellular responses by the expression of heat shock proteins. The project was developed in Biometeorology and Ethology Laboratory, Faculty of Animal Science and Food Engineering, University of São Paulo, Pirassununga-SP. Were used 20 Nellore pluriparous cows, cyclical, kept in grazing system. The experimental period preceded the 2013\' breeding season and ended up in artificial insemination. To classify animals in relation to heat management the vaginal temperature was monitored for six days through 16 data loggers (n=16). In order to better understand the heat management, other physiological responses, including rectal, tail and eye temperatures, respiratory rate and sweating rate were taken during the final four days of vaginal temperature monitoring. For gene expression was harvested blood samples (n=20). in vitro heat shocks were performed at 38ºC, 40ºC and 42ºC during two hours. After the heat treatment was obtained the leukocyte pellet for later RNA extraction by TRIzol method. Ten cows were chosen with the best RNA concentration results, five belonging to the group of cows efficient on heat management and five inefficient (n = 10). RT-PCR was performed with SuperScript III kit. The real-time polymerase chain reaction (qPCR) occurred in StepOnePlus® Applied Biosystems instrument using the SYBR® Green as fluorescent marker to the target validated genes HSPA1A, HSPD1, HSP90AA1, HIF1A and the endogenous ACTB, RPL15 and PPIA. Data were analyzed using ANOVA, regression and correlation SAS 9.2. The cows were classified as efficient and inefficient through angular coefficients, derived from regression of vaginal temperatures for the gain and heat loss periods. Efficient cows had lower rectal temperature 37.65ºC (P<0.01), higher sweating rate 528.73 g. m ². h-¹ (P<0.06). At cellular level, the increase of in vitro programmed temperature has not increased the transcripts amount, promoting the maintenance at 38ºC and 40ºC and decline at 42ºC. The decreasing order of transcripts amount was HSPA1A, HSPD1 and HSP90AA1. It can be concluded that Nellore cows with different heat managements has different thermoregulatory responses. The HSPA1A showed the highest transcripts abundance being considered as a molecular marker for thermotolerance, for being more sensitive to temperature and better conserved. There was no difference in gene expression for heat shock proteins between animals classified by heat management

Temperatura de superfície corporal em vacas leiteiras mestiças em condições climáticas do Triângulo Mineiro/Brasil

O artigo não apresenta resumo em português

Temperatura de superfície corporal em vacas leiteiras mestiças em condições climáticas do Triângulo Mineiro/Brasil

O artigo não apresenta resumo em português

Rectal temperature and conception of inseminated crossbred dairy cows

In tropical and subtropical regions animals suffer pronounced heat stress effect on reproductive function, being one of the most noticeable effects the reduction of conception rate. When evaluating animals heat stress, rectal temperature measurement is important tool because indicates heat release mechanisms became insufficient to maintain homeothermy. This study aimed to evaluate body temperature at fixed time artificial insemination of crossbred dairy cows and their conception at 30 days pregnacy. Experiment was performed from April 26, 2010 to January 28, 2012 at Estação Experimental Glória of Universidade Federal de Uberlândia, at Triângulo Mineiro, Brazil. One hundred-twelve crossbred dairy cows and heifers were used. At the moment of insemination, animals were housed in shaded pen and body temperature was collect using clinical thermometer introduced in rectal mucosa. Environmental variables collect were air temperature, maximum temperature, minimum temperature and relative humidity. Data were analyzed in two different periods: from April to September (mild weather-MW) and from October to March (hot weather-HW). The statistical model included the effect of category, period, pregnancy diagnosis and their interactions, comparing means by Tukey’s test, with a significance level of 5%. Means and standard deviations of air temperature, maximum temperature, minimum temperature and relative humidity for MW and HW, were respectively, 23.85 ± 3.44°C and 23.15 ± 2.07°C; 29.16 ± 1.79°C and 29.84 ± 3.40°C; 16.20 ± 3.00°C and 21.06 ± 2.28°C; 82.72 ± 8.49% and 94.54 ± 4.66%. Rectal temperatures are presented on Table 1. Thermal environment of both weathers set up thermal comfort condition. Rectal temperature detected was within normal limits and it did not vary with pregnancy stage or weather condition, but was higher on heifers on mild weather probably because more reactivity behavior

Effect of Acute and Cumulative Stress on Gene Expression in Mammary Tissue and Their Interactions with Physiological Responses and Milk Yield in Saanen Goats

This study addresses the hypothesis that different acute stressors can cumulatively decrease milk yield. In fact, in a time of global warming, the impact of environmental stress and farm management practices on milk production remains unclear. In this context, our objective was to investigate the effect of acute and cumulative stress on gene expression in mammary tissue and their interactions with physiological responses and milk yield in Saanen goats. Thirty lactating goats were subjected to two treatments: (1) control (CT), in which goats were maintained following a habitual routine under comfort conditions; (2) stress (ST), in which the goats were subjected to different types of environmental stress: heat stress, adrenocorticotropic hormone administration, hoof care management, and exposure to rain. These stressors were performed sequentially, with one stress per day on four consecutive lactation days, to evaluate their effect on milk quality and milk yield. Our results showed that compared to CT goats, cumulative stress increased the gene expression of glucocorticoid receptor (GR), interferon-gamma (IFN-γ), superoxide dismutase (SOD), and catalase (CAT) in mammary tissue, which are indicators of cortisol action, inflammatory response, and antioxidant enzymes. Furthermore, the acute challenges imposed on ST goats changed their rectal temperature and respiratory frequency and increased cortisol, glucose, cholesterol, triglycerides, and high-density lipoprotein release in plasma when compared to CT goats. Although these physiological and metabolic responses restore homeostasis, ST goats showed lower milk yield and higher somatic cell count in milk than CT goats. In conclusion, the results confirmed our initial hypothesis that different acute stressors cumulatively decrease the milk yield in Saanen goats