Heat loss efficiency and thermoregulation responses of Nellore cows

Abstract: Nellore cattle is well adapted to tropical environmental conditions with good thermoregulatory characteristics. However, knowledge related to body temperature regulation and acclimatization mechanisms are still scarce. This investigation aimed to understand the heat loss efficiency and thermoregulation responses of Nellore cows in tropical climate conditions. In this study was used 16 healthy purebred Nellore cows classified by heat loss in efficient and non-efficient using the vaginal temperature continuously monitored by data-loggers. The rectal, tail and ocular temperatures, sweating rate and respiratory frequency were also measured to understand the thermoregulatory responses and correlate to previous classification. In our findings, were noticed that according to heat loss classification the nonefficient cows showed greater amplitude of temperature variation. The body temperature increased from 12:00 PM to 19:00 PM with gradual decreased from 19:00 PM to 07:00 AM, reaching the peak in both groups at around 16:00 PM. In addition, the efficient cows presented higher sweating rate than non-efficient that presented higher rectal temperature, therefore the reduction of body temperature by improving evaporative mechanisms is a good trait of acclimatization to heat. No statistical difference was observed for the other physiological variables between groups. In conclusion, the methodology to classify the cows by heat loss using vaginal data loggers allowed us to distinguish Nellore cows according to their body temperature regulation, being feasible and reproducible. Furthermore, the efficiency to heat loss of this bred was mainly associated with sweating capacity

Termografia infravermelha da superfície ocular como indicador de estresse em suínos na fase de creche

Weaning is a critical phase in pigs’ life due to maternal separation and the introduction of a new diet. Infrared thermography measurement taken in the ocular region appears to be a reliable indicator of the stress condition of the pig. The aim of this study was to eva- luate the relationship between ocular surface temperature by infrared thermography and cortisol in piglets post weaning. Sixty-six piglets were evaluated once a week, during 7 weeks, in two periods of the day (7am and 15pm) and ocular surface temperature and dor- sal surface temperature were collected using a thermographic camera and a laser surface thermometer, respectively. Saliva was also collected to determine salivary cortisol. Statisti- cal analysis included fixed effects of week and period of the day and their interaction, and relationship between thermography, dorsal surface temperature and cortisol were done by Pearson’s correlations with 5% significance level. Salivary cortisol did not differ betwe- en periods, but it was higher in the first three weeks after weaning (P<0.05). During the first two weeks after weaning cortisol presented high and positive correlation (P<0.05) between ocular surface temperature (0.89) and dorsal surface temperature (0.80). The two superficial temperatures had a moderate and positive association (r=0.41; P<0.0001) during all experiment. This study highlights that the ocular surface temperature obtained through infrared thermography can be a superficial body temperature indicators, besides being a non-invasive and fast method of measurement. However, more research is needed to deepen the relationship between ocular surface temperature and cortisol during chronic stres

Cortisol fecal em ovinos: curva de excreção e estabilidade

Objetivou-se determinar a curva de excreção do cortisol fecal perante exposição a uma situação de estresse, correlacionando com concentrações de cortisol sanguíneo. Foram colhidas as fezes de seis fêmeas mestiças (Dorper x Santa Inês) durante 24 horas após a aplicação do hormônio adrenocorticotrófico (ACTH), além de colheitas de sangue realizadas antes da aplicação do ACTH (0,6 UI por kg PV, Porcine ACTH 1-24, Sigma, St. Louis, MO, USA), 60, 120 e 300 minutos depois. Os dados da curva de excreção foram analisados por ANOVA, bem como pela correlação entre os valores de cortisol sanguíneo, fecal e reatividade. Para avaliação das variáveis comportamentais foi realizada a transformação de escala dos dados para “arco-seno raiz de porcentagem”, procedendo-se à análise de variância com efeitos de dia (1, 2 e 3) com análise individual por animal. Os parâmetros de cortisol sanguíneo, frequência respiratória e temperatura retal foram analisados pelo teste t e correlação de Pearson. Todas as comparações de médias foram realizadas por teste F e teste t (PDIFF). A reatividade durante a colheita não exerceu efeito significativo sobre os valores de cortisol sanguíneo. Os valores de cortisol sanguíneo apresentaram médias maiores aos 60 minutos após a aplicação do ACTH e, após 300 minutos as ovelhas apresentaram níveis de cortisol considerados normais para ovinos sem estresse. Por outro lado, o pico de cortisol nas fezes foi verificado aproximadamente 10 a 12 horas após o pico de cortisol no sangue, não sendo verificadas diminuições significativas nas concentrações que indicassem o retorno aos níveis basais durante o período de 24 horas (P>0,05)

Heat shock response in PBMCs of Nellore cows after in vitro thermal stress

Abstract Adaptation is an important feature to be studied in animals when thinking about maintenance and raise of productivity. Although Nellore breed is widely disseminated in Brazil, the knowledge related to its thermotolerance in tropical climate conditions remains unknown. Hence, the aim of this study was to understand the Nellore breed cellular adaptation when exposed to heat shock in vitro, using peripheral blood mononuclear cells (PBMCs). The comprehension of the most expressed and sensible heat shock proteins in Bos taurus indicus may elucidate a molecular marker for genetic improvement related to thermotolerance. Previous to blood sampling, the physiological parameters of 16 cows were measured in order to classify them in efficient and non-efficient on heat loss. For this experiment, the blood was collected in three different heparin tubes by jugular venipuncture only in 10 cows, 5 efficient and 5 nonefficient, at morning. The molecular analyzes were performed in Physiology and Molecular Endocrinology Laboratory, Faculty of Veterinary Medicine and Animal Science, University of São Paulo. After sampling, each blood tube were placed in three different water bath devices calibrated for: 38°C, 40°C and 42°C for two consecutive hours. The PBMCs were separated, washed with hemolysis solution, the RNA extracted, the cDNA synthetized and performed the qPCR for the genes HSP60, HSP70 and HSP90. There was a maintenance on HSPs transcripts on 38°C and 40°C and a decrease on all HSPs transcripts at 42°C. Among all, the HSP70 was the most expressed at 38°C and 40°C, elucidating its protective importance. No difference was observed between gene expression and heat loss efficiency. In conclusion, the Nellore cell adaptability was confirmed by the maintenance of heat shock proteins 60, 70 and 90 kDa. The pathway for understanding responses involving thermotolerance is still long and requires more knowledge of cell signaling, either in vitro or in vivo conditions. Taken together, these informations may contribute in future keys for genetic selection of adapted animals

Application of a thermolysis capacity test for dry and lactating cows

The heat stress has negative effects on animal comfort and productivity. Genetic progress in milk production is related closely to an increase in metabolic heat increment, which makes cows more affected by heat stress. Individual thermotolerance can be an important tool in genetic selection. The study aimed to validate a new proposal for assessing the ability of heat loss after sun exposure in cows and its application in dry and lactating cows kept or not on thermal comfort condition. The test consists in three days of sun exposure for one hour followed by one hour rest in the shade to determine the individual thermolysis capacity (TC) by the variables rectal temperature, body surface temperature, internal tail base temperature, respiratory rate, plasma cortisol and IGF-I. In the new proposal these physiological variables were measured before sun exposure, after 50 min in the sun and after one hour in the shade (T0, T1 and T2 consecutively). The test in which this new test was adapted lacked T1.The three day test was applied with similar meteorological variables as black globe temperature of 48.1°C (1.32), air temperature of 31.7°C (0.92) and relative humidity of 39.5% (3.38). The differences between dry and lactating cows were measured in 28 animals divided into two experimental groups housed in free-stall with and without evaporative cooling system (mist and fans). The animals remained at the facility for seven months (from spring to summer) then after they were subjected to heat stress and the TC (10-[(T1-T0)-(T2-T1)]) was determined. There was no difference between the TC of dry and lactating cows (P>0.05), but respiratory rate and IGF-I were greater and body surface was lower in dry cows during sun exposure (P0.05). The thermolysis capacity test was validated and can be used for either dry or lactating cows. Milk production did not influence the thermoregulatory responses of Holstein cows, but when lactating and kept in cooling system they showed better thermolysis capacity index

Reactivity in ewes submitted to invasive and non-invasive techniques of samples collections

The first-time experience of a procedure or with a person should be as positive as possible. If a procedure is very aversive or painful at first contact, it can be difficult to persuade the animal to return to the local where this occurred. For this reason it is important to develop a strategy in experimental and routine activities, taking into account that sheep has often reactive temperament. This study aims to evaluate the possible decreased of the reactivity in sheep across the prior presentation of invasive and non-invasive techniques for collecting saliva and blood samples for cortisol analysis and transepidermal water loss through the use of Vapometer®. Saliva was collected using Sallivetes® and blood was taken from the jugular vein in heparinized tubes, placed on ice, and then centrifuged at 4 °C and 3,000 for 15 min. The tubes containing serum were stored at −20 °C until CORT and IGF-I determination using an enzyme immunoassay kit (Diagnostic Systems Laboratory, Webster, TX). The collection of transepidermal water loss (TEWL) was performed using a Vapometer ® (Dolphin, Finland) device. In the three techniques the ewes were always contained by the same person for the time necessary to collect the variable. To take saliva samples the animals were contained during 2 minutes, for blood samples during 1 minute and for TEWL during 30 seconds. The test consists of six data collections performed with increasing intervals between days, checking the possible adaptation of the animal management factors. The first interval was 2 days and after 3 days, then after 4 days, and the next was 7 days and again 7 days, totaling 24 days of experiment. Before sampling saliva, blood or TEWL the reactivity of the ewes was analyzed by a composite score scale when animals were inside the chute. The composite score (CS) is a combination of the scores of: entrance (1 to 4), respiratory rate (1 to 4), vocalization (0 or 1), movement (1 to 4) and flight speed (1 to 4). After the chute a score of containment (1 to 4) was attributed by the same person, which had contained the animal. The experimental unit was each animal and the average of the observations in each sheep was used for the statistical analysis. The observed data of transepidermal water loss, salivary cortisol and serum cortisol were subjected to analysis of variance, with the days and the groups as fixed effect. In case of significant results (P<0.05) it was adopted Tukey-Kramer Test as the procedure for multiple comparisons. Cortisol decreased for saliva and blood groups during the experiment days (P<0.05), showing habituation of the animals to the management. In the same way, TEWL had the highest mean value on day 1, and decreased afterwards (P<0.05). The score of containment was lower for the TEWL group compared to the other two groups (P<0.05), however the higher value was observed on day 5, seven days after a sampling (P<0.05). The score of containment of saliva and blood groups decrease in day 2, but return to increase in the next sampling day (P<0.05). The CS was higher for saliva group (P<0.05). On day 5 CS increased for blood group, but decreased for TEWL (P<0.05). The invasive techniques (saliva and blood) increased the reactivity of sheep before and after retention. Sheep are reactive animals therefore need a more gentle handling during the experiment with invasive samples

Reactivity of Nelore cows during reproductive management

The Nelore breed is recognized as rustic and well adapted to parasites and high temperatures, and these features composes a good part of the Zebu genetic group. However, they are considered more reactive than other breeds and for this reason they require more time to be managed, putting at risk the safety of employees, the animals themselves and also compromise installations. In order to solve problems such as short duration and high nocturnal occurrence of oestrus many properties choose to perform artificial insemination during the breeding season. At this time, there is an intensification of human-animal interaction in short periods and at different times. When animals are more reactive on handling and are exposed to an uncomfortable thermal environment the stress rises causing impacts on reproduction and production. Stress is comprehended by a set of behavioral and physiological changes when in threatening or uncomfortable situations caused by stressors (physical environment, social or management practices). Some farms have already made the selection for temperament, using different methods of evaluation in accordance with the conditions of creation and infrastructure available at the property. Thus, the aim of this research was to evaluate the reactivity of Nelore cows in different managements that occur in the breeding season. Was evaluated 20 multiparous Nelore cows from October 2013 to March 2014, during the spring and summer seasons with air temperature averages ranging from 22.7 ± 4.9°C to 25.2 ± 4.7°C, in the Campus’ beef cattle sector of the Universidade de São Paulo in Pirassununga. Reactivity was evaluated using scores of escape velocity or output speed using subjective scores: 1 - does not leave the chute, needs to be touched; 2 - walking out the chute; 3 - exits the chute at average speed; 4 – exists the chute quickly. So, as higher is the score as higher is the stress. The scores were given immediately after the animals exists the chute from the managements of sync (M1), artificial insemination (M2), pregnancy diagnosis at 30 days (M3), pregnancy diagnosis at 60 days (M4), pregnancy diagnosis at 90 days (M5). The data of the escape score was analyzed using analysis of variance, using the GLM procedure of SAS and means were compared using the Tukey test at 5%. It was noted that, there was no differences on the average of escape score (2.34) at the managements M1, M2, M3 and M4. However, in management M5 the average was 1.79 differing from the other managements (P<0.05). In this way, at the last management, there was a reduction of 23.50% in escape score. So, we conclude that with the increase in frequency of human-animal interactions during the reproductive managements, there is a decrease in the escape score and consequently the stress, contributing to the agility on each management, security of employees, lower physical trauma on animals and damages to facilities

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

The Effect of Different Formulations of Praziquantel in Reducing Worms in the Prepatent Period of Schistosomiasis in Murine Models

Schistosomiasis is a widely distributed parasitic disease and one of the most important neglected tropical diseases globally, for which Praziquantel® (PZQ) is the only available treatment. In this context, tests with new PZQ formulations become relevant for disease control. This study evaluated the effects of PZQ treatment in the prepatent phase of schistosomiasis using two formulations: nanoencapsulated (PZQ-NANO) and active pharmaceutical ingredient (PZQ-API). Five experimental groups were established, for which the following serological parameters were evaluated: ALT, AST, ALP, and TP. Animals treated with PZQ-API at 15 and 30 days post-infection showed decreased eggs per gram of feces (EPG) compared to untreated infected animals. The same animals showed reductions of 63.6 and 65.1%, respectively, at 60 days post-infection. Animals treated with PZQ-NANO experienced no significant changes in EPG at any time of observation. Animals treated with either PZQ-API or PZQ-NANO had higher ALT and AST levels in the patent period (60 and 90 days post-infection). Treatment with PZQ, either API or NANO, at 15 days post-infection reduced AST, ALT, and TP levels. It is concluded that prepatent treatment with PZQ-API can reduce the parasite load of infected animals and that treatment at 15 days post-infection can prevent increased serum levels of ALT, AST, and TP.Fil: Paulino, Érica Tex. Fundación Oswaldo Cruz; BrasilFil: Ribeiro de Lima, Monique. Fundación Oswaldo Cruz; BrasilFil: Viçosa, Alessandra Lifsitch. Fundación Oswaldo Cruz; BrasilFil: Hooper da Silva, Cleber. Fundación Oswaldo Cruz; BrasilFil: Salomon, Claudio Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Real, Daniel Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Leonardi, Darío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Mello Silva, Clélia Christina. Fundación Oswaldo Cruz; BrasilFil: Almeida de Moraes Neto, Antonio Henrique. Fundación Oswaldo Cruz; Brasi

Abrupt weaning type combined to stress during late pregnancy in sheep present economic losses on carcass and low testicular development in lambs

This study investigates the combined effect of the progressive or abrupt weaning after the stress during middle and late pregnancy on performance and development of lambs. Twenty-four male lambs were used, born from 18 Santa Ines ewes that were divided into three experimental groups. Pregnant ewes were submitted to the application of Lipolysaccharides E. coli (LPS) during the 70 th day of pregnancy (Ig; n=12) or at the 120 th day (Fg; n=8). Animals were kept as control (Cg; n=14). Lambs born in a 6 day interval were subjected to two types of weaning (Pw: progressive weaning; Aw: abrupt weaning at 45 days of age). Lamb data, including testicular development, yield carcass and economic cost were analyzed. Means were compared by F test and Student's t test (P0.05). The highest yields in gross margin was observed for the Cg group and the lowest for Fg (P0.05). On lambs’ testicular weight, Cg average value was higher than Fg (P0.05). The combined effect of LPS challenge as a simulated disease process during late pregnancy and abrupt weaning change the testicular weight and the yield carcass, resulting in economic losses