Surviving heat: Resilience of Nellore bulls to solar radiation exposure

We aimed to assess the physiological and biophysical responses of Nellore bulls exposed to solar radiation in semiarid conditions throughout the day. Sixteen Nellore bulls were examined in Tibau city, Northeast Brazil (5°52ʹ South, 37°20ʹ West, and 37 m above sea level) over four nonconsecutive days, with data collection taking place at one-hour intervals between 7:00 am and 5:00 pm. Four animals were analyzed each day and kept exposed to the sun for the duration of the study. The average age of the animals was three years, and their average body weight was 650±32 kg. The meteorological station measured air temperature (°C), relative humidity (%), solar radiation (W.m-2 ), and black globe temperatures (°C) every minute, while a digital anemometer thermohygrometer measured wind speed (m.s-1 ) at the same time. Respiratory rate (breaths.min-1 ), expired air temperature (°C), rectal temperature (°C), and body surface temperature (°C) were measured as physiological variables. Biophysical equations were used to estimate the sensible and latent heat transfer mechanisms (W.m-2 ). The air temperature ranged from 28.5 to 32.5°C, and direct solar radiation was between 21 and 891 W.m-². Between 11:00 am and 1:00 pm, the study observed heat gain through longwave radiation, which reached an average of 250 W.m-2 , with a significant increase (P < 0.05) in respiratory rate and body surface temperature during this time. Convection was significant in heat dissipation, particularly when the wind speed was increased from 11:00 am. However, latent heat loss mechanisms were more effective in losing excess body heat under total sun exposure, despite the positive effect of convection. The study findings showed that Nellore bulls maintained their body temperature within a narrow range even when exposed to high solar radiation, thus demonstrating the efficiency of physiological and biophysical mechanisms during times of greater thermal challenge.(AU)

Effects of heat-stress on oocyte number and quality and in vitro embryo production in Holstein heifers

Background: This study aimed to determine the effects of environmental temperature on the number and quality of oocytes and embryo production rates obtained by performing ovum pick up (OPU). Heat stress leads to long-term, short-term, visible, and invisible effects in dairy cows. Its effects on reproduction are evident in all stages, from oocyte development to birth. Disturbance in ovarian follicle development, follicular dominance deficiency, anoestrus, polyspermia, embryonic losses, decreased fetal growth, and abortion are some examples of responses to these effects. The aim of the present study was aimed to determine the effects of ambient temperature on oocyte quality and number and embryo production rates. Materials, Methods & Results: The animal material used in this study comprised 10 Holstein heifers. At the beginning of the study, the heifers were 13-15 months old. OPU was performed at different times of the year, and weather conditions were recorded. Grouping according to ambient temperature was done as < 10°C (group 1), 10-25°C (group 2), and > 25°C (group 3). The veterinary ultrasonography device and a set of compatible intravaginal OPU probe, catheter, and aspiration device were used for OPU application. All antral follicles with diameters of 2-8 mm in the ovaries were aspirated. The aspirated follicle fluids were examined under a stereo microscope, and the cumulus-oocyte complexes (COC) were collected and classified according to their structure. A, B, and C-quality oocytes were included in the in vitro embryo production process. After performing 69 OPUs on random days of the cycle, the number of oocytes per OPU was found to be 8.72, 6.32, and 6.85 in groups 1, 2, and 3, respectively (P < 0.05). The number of viable oocytes per OPU was 6.83, 4.64, and 4.65 in groups 1, 2, and 3, respectively (P < 0.05). The statistical difference between the first group and the other groups was significant for cleavage and blastocyst counts (P < 0.05). Discussion: All the negative effects of heat stress on animals resulted from the increased body temperature. Reproductive performance is adversely affected by high temperatures and humidity during periods of high ambient temperatures. Metabolic heat is released, and the heat load increases due to the metabolism of nutrients in cattle. Internal body temperature is regulated via the dissipation of metabolic heat to the environment. The amount of heat dissipated via conduction and convection depends on the unit body weight, surface area, skin and coat color, difference in temperature gradient of the animal and ambient temperature, and humidity. In the present study, it was determined that the blastocyst development rates of the oocytes obtained in the warm season (>25°C [group 3]) were lower than those of the other groups. It was concluded that this may be because the oocytes developed under chronic heat stress in the animals, and several cycles were required to enhance oocyte quality and developmental potential. Additional studies are needed to investigate the response of oocytes obtained with OPU to heat stress during embryonic developmental stages and to determine the sensitivity and effects of embryonic tissue damage according to developmental stages. Based on the results of the present study, it was concluded that performing OPU and in vitro embryo production (IVEP) when the ambient temperature is close to the thermoneutral limits may increase the blastocyst development rates.

Total heat loss in broilers fed with different lipid sources

To meet the growing demand for poultry products, many producers have decided to increase the density of animals per square meter. This, coupled with global warming, creates a severe problem for the poultry industry, as it is common to observe birds moving away from the thermal comfort zone. Therefore, the objective of this study was to evaluate the effect of three lipid sources and three levels of inclusion in broiler diets on sensible heat loss. Three hundred twenty-four female broilers from the Ross 308 line were housed in cages in an open house and distributed into nine different treatments. The body surface temperature was observed with an infrared thermography camera. Heat loss was analyzed by radiation, and convection was calculated by equations at weeks three, four, and six of broiler life, considering the importance of measuring and analyzing the following variables: wind speed, bird weight, bird area, ambient temperature, and relative humidity, among others. The treatments had no significant effect on Qt; however, the inclusion of palm oil, chicken oil at 3%, and sacha inchi oil at 9% can be an alternative in broiler chicken feed since they tend to reduce Qt at day 42 of life.

Microwave and convective air on drying of araucaria angustifolia seeds / Utilização de micro-ondas e ar quente na secagem de sementes de araucaria angustifolia

Microwave drying has shorter processing times compared with convection drying, which results in high quality products and reduced energy consumption. The objective of this study is to evaluate the drying process of Araucaria angustifolia seeds using hot air at atmospheric pressure by applying microwaves (300 W and 500 W), and comparing them with the conventional drying process using hot air (80 °C). The drying time using hot air with microwaves at 500 W and 300 W was reduced by 83.33% and 73.89%, respectively, compared with conventional drying. The drying process occurred in the transient regime, with the predominance of a period of decreasing drying rate. The internal temperature of Araucaria seeds increased with the exposure time to the drying process, whereas the moisture content decreased. This tendency was greater for seeds subjected to electromagnetic fields, especially those exposed to higher power. The total phenolic compounds (TPCs) were lower by microwave drying when compared with conventional drying. The TPC loss was influenced by the internal temperature of the seed. Alternative methods to promote the increased retention of phenolic compounds during the drying process include decreasing the microwave power before the end of drying, combining traditional microwave-associated drying methods, and controlling the applied microwave power.

Comparados aos secadores por convecção, os secadores dielétricos têm tempos de secagem mais curtos, proporcionando produtos de melhor qualidade e consequentemente menor consumo de energia. O objetivo deste estudo foi avaliar os processos de secagem de sementes de Araucaria angustifolia usando ar quente à pressão atmosférica, aplicando micro-ondas (300 W e 500 W) e compará-los ao processo de secagem convencional com ar quente (80 ºC). O tempo de processo de secagem usando ar quente com micro-ondas foi reduzido em 83,33% na potência de 500 W e 73,89% a 300 W, quando comparado à secagem convencional. Os processos de secagem ocorreram no regime transiente, com predominância do período de taxa decrescente. Observou-se que os valores da temperatura interna aumentaram com o tempo de exposição do material ao processo, enquanto a umidade diminuiu. Essa tendência foi maior para sementes submetidas a campos eletromagnéticos, principalmente aquelas expostas a maior potência. Os compostos fenólicos totais foram menores na secagem por micro-ondas quando comparados à secagem convencional. A perda de compostos fenólicos foi influenciada pela temperatura no interior do produto. As alternativas para promover maior retenção de compostos fenólicos no processo de secagem seriam a diminuição da potência antes do final da secagem, a combinação dos métodos tradicionais de secagem associados às micro-ondas e o controle da potência a ser aplicada no micro-ondas.

Microwave and convective air on drying of araucaria angustifolia seeds / Utilização de micro-ondas e ar quente na secagem de sementes de araucaria angustifolia

Microwave drying has shorter processing times compared with convection drying, which results in high quality products and reduced energy consumption. The objective of this study is to evaluate the drying process of Araucaria angustifolia seeds using hot air at atmospheric pressure by applying microwaves (300 W and 500 W), and comparing them with the conventional drying process using hot air (80 °C). The drying time using hot air with microwaves at 500 W and 300 W was reduced by 83.33% and 73.89%, respectively, compared with conventional drying. The drying process occurred in the transient regime, with the predominance of a period of decreasing drying rate. The internal temperature of Araucaria seeds increased with the exposure time to the drying process, whereas the moisture content decreased. This tendency was greater for seeds subjected to electromagnetic fields, especially those exposed to higher power. The total phenolic compounds (TPCs) were lower by microwave drying when compared with conventional drying. The TPC loss was influenced by the internal temperature of the seed. Alternative methods to promote the increased retention of phenolic compounds during the drying process include decreasing the microwave power before the end of drying, combining traditional microwave-associated drying methods, and controlling the applied microwave power.(AU)

Comparados aos secadores por convecção, os secadores dielétricos têm tempos de secagem mais curtos, proporcionando produtos de melhor qualidade e consequentemente menor consumo de energia. O objetivo deste estudo foi avaliar os processos de secagem de sementes de Araucaria angustifolia usando ar quente à pressão atmosférica, aplicando micro-ondas (300 W e 500 W) e compará-los ao processo de secagem convencional com ar quente (80 ºC). O tempo de processo de secagem usando ar quente com micro-ondas foi reduzido em 83,33% na potência de 500 W e 73,89% a 300 W, quando comparado à secagem convencional. Os processos de secagem ocorreram no regime transiente, com predominância do período de taxa decrescente. Observou-se que os valores da temperatura interna aumentaram com o tempo de exposição do material ao processo, enquanto a umidade diminuiu. Essa tendência foi maior para sementes submetidas a campos eletromagnéticos, principalmente aquelas expostas a maior potência. Os compostos fenólicos totais foram menores na secagem por micro-ondas quando comparados à secagem convencional. A perda de compostos fenólicos foi influenciada pela temperatura no interior do produto. As alternativas para promover maior retenção de compostos fenólicos no processo de secagem seriam a diminuição da potência antes do final da secagem, a combinação dos métodos tradicionais de secagem associados às micro-ondas e o controle da potência a ser aplicada no micro-ondas.(AU)

Biophysical responses of Santa Inês and crossbred Santa Inês-Dorper (F1) ewes to a hot environment

This study aimed to evaluate the biophysical responses of Santa Inês ewes and crossbred Santa Inês-Dorper ewes in a hot environment. Physiological parameters were measured: rectal temperature, respiratory rate, coat surface temperature, skin surface temperature, and heart rate. Biophysical parameters were also calculated: heat exchanges by cutaneous convection and radiation, as well as heat storage and thermal conduction in fleece. Throughout the collection period, meteorological variables were similarly monitored. The statistical design was completely randomized in a factorial 2 x 2 (two genotypes and two shifts). According to meteorological variables, the afternoon shift introduced itself with greater heat stress compared with the morning shift. The effect of interaction between genotypes and shifts for respiratory rate, rectal temperature, skin surface temperature, and hair coat surface temperature showed that genotypes exhibit different physiological behavior under similar heat stress situations. Heart rate had the effect of two sources of variation. As for the biophysical parameters, radiation and conduction exchanges in fleece presenting with the shift effect. Heat storage was slightly higher in Santa Inês ewes than in their crossbred Santa Inês-Dorper ewes. It was therefore concluded that crossbred ewes use physiological mechanisms more vigorously to perform heat exchanges, similar to Santa Inês ewes, which have become more adapted to a hot environment. (AU)

Biophysical responses of Santa Inês and crossbred Santa Inês-Dorper (F1) ewes to a hot environment

This study aimed to evaluate the biophysical responses of Santa Inês ewes and crossbred Santa Inês-Dorper ewes in a hot environment. Physiological parameters were measured: rectal temperature, respiratory rate, coat surface temperature, skin surface temperature, and heart rate. Biophysical parameters were also calculated: heat exchanges by cutaneous convection and radiation, as well as heat storage and thermal conduction in fleece. Throughout the collection period, meteorological variables were similarly monitored. The statistical design was completely randomized in a factorial 2 x 2 (two genotypes and two shifts). According to meteorological variables, the afternoon shift introduced itself with greater heat stress compared with the morning shift. The effect of interaction between genotypes and shifts for respiratory rate, rectal temperature, skin surface temperature, and hair coat surface temperature showed that genotypes exhibit different physiological behavior under similar heat stress situations. Heart rate had the effect of two sources of variation. As for the biophysical parameters, radiation and conduction exchanges in fleece presenting with the shift effect. Heat storage was slightly higher in Santa Inês ewes than in their crossbred Santa Inês-Dorper ewes. It was therefore concluded that crossbred ewes use physiological mechanisms more vigorously to perform heat exchanges, similar to Santa Inês ewes, which have become more adapted to a hot environment.

Produção de calor metabólico e transferência de calor sensível em codornas

O objetivo deste trabalho foi estudar o equilíbrio térmico de codornas comerciais adultas em fase de produção de ovos, considerando a produção de calor metabólico e os mecanismos de transferência de calor sensível entre as aves e o ambiente. A tese foi desenvolvida em dois experimentos: no experimento I, objetivou-se avaliar a produção de calor metabólico em codornas ao longo das 24 horas do dia (ciclo nictemeral) em conforto térmico. Para isso, foram utilizadas 40 codornas fêmeas, de duas subespécies japonesas (Coturnix coturnix japonica) e europeias (Coturnix coturnix coturnix). As aves foram avaliadas em duas fases, Fase I: entre 55 e 65 dias e Fase II: entre 110 e 120 dias de idade. Utilizou-se a metodologia da calorimetria indireta e uma ave de cada subespécie foi inserida em um trocador de calor e analisadas simultaneamente durante 24 horas. De forma síncrona, também foram analisadas as variáveis ambientais: temperatura do ar (ºC), concentração do ar atmosférico (dióxido de carbono e oxigênio %) e pressão parcial do vapor do ar (kPa). O calor metabólico (W m-2) das aves foi calculado considerando que 76% é proveniente do consumo de oxigênio e 23% é devido à produção de dióxido de carbono, além da ventilação (L s-1) e da superfície corporal das aves. Os dados foram analisados pelo método dos quadrados mínimos considerando os efeitos de subespécie (japonesa ou europeia), dia (1 a 20), horas do dia (meia noite às 23h00), e efeito da interação entre subespécie com o dia, e da subespécie com a hora do dia. Os resultados mostram que a todas as variáveis analisadas a produção de calor, o consumo de O2, a produção de CO2 e frequência respiratória, tiveram efeito significativo (P< 0,001). Os principais resultados encontrados da produção de calor metabólico de codornas em termoneutralidade mostrou diferença significativa entre as subespécies (P< 0,001). Quando estão com idade entre 55-65 dias, a fisiologia entre as subespécies é distinta, nesta idade as codornas europeias continuam o crescimento e ganho de massa corporal, além de coincidir com a produção de ovos, o que demanda que a produção de calor metabólico seja maior do que das japonesas. Porém, em período de pico de produção de ovos com idade entre 110-120 dias essa produção de calor continua diferente entre as subespécies (P< 0,001) sendo maior nas europeias 67,3 W m-2 do que nas japonesas 58,8 W m-2. Além disso, quanto a proporção do tamanho do ovo em relação ao tamanho da codorna, as japonesas produzem ovos que são 5,8% do seu peso vivo, enquanto as codornas europeias que produzem ovos com a proporção de 4,3% da sua massa corporal. Conclui-se que as codornas japonesas produzem menos calor metabólico para se manterem em produção, tornando-as mais eficientes para a produção de ovos, sendo que são ovos maiores em proporção ao tamanho do corpo da ave em comparação com as codornas europeias, que produzem maior quantidade de calor para a postura de um ovo por dia. Mostrou o quanto as codornas europeias são mais exigentes quando comparadas as codornas japonesas. Reforçando a necessidade de programas nutricionais e ambientais específicos para atender às demandas de cada subespécie e em diferentes exigências fisiológicas de acordo com a idade. No experimento II, objetivou-se avaliar a transferência de calor sensível em codornas japonesas, considerando os mecanismos de radiação de ondas longas e convecção, criadas em galpão convencional sem controle ambiental. Para isso, foram analisadas as variáveis meteorológicas: a temperatura do ar (TAR, ºC), a umidade relativa do ar (UR, %) e a temperatura do globo negro (TGN, ºC); e as variáveis fisiológicas: a temperatura cloacal (TC, ºC) e superficial (TS, ºC) das codornas. A temperatura superficial foi aferida por uma câmera termográfica em 50 codornas japonesas adultas, machos e fêmeas, com 270 dias de idade, durante 10 dias, nos horários das 08h00 e às 15h00. Os dados foram analisados pelo método dos quadrados mínimos e foram analisados os efeitos de gênero (macho e fêmea), período (manhã e tarde) e regiões do corpo (cabeça, corpo e pés). A temperatura da superfície das codornas apresentou alta correlação com a temperatura do ar, com a temperatura radiante e com a radiação de ondas longas. Todos esses fatores influenciaram a transferência de calor e o fluxo de calor sensível total foi de 64,02 W m-2. A transferência de calor sensível nos animais é totalmente dependente da temperatura ambiente. A temperatura operativa pela manhã foi de 22,48°C, que permitiu maior gradiente de temperatura entre o ar e a superfície da codorna, portanto, ocorreu maior transferência de calor 82,19 W m-2 das aves para o ambiente. À tarde a transferência foi menor 45,70 W m-2, porque neste momento a temperatura operativa foi maior 30,84 ° C. A comparação entre os gêneros mostrou que a transferência de calor foi maior nas fêmeas 67,37 W m-2 do que nos machos 60,53 W m-2. A cabeça mostra-se como importante janela térmica com capacidade de dissipar 78,24 W m-2, enquanto o corpo + pés de 56,80 W m-2 nas codornas. A dissipação de calor nas aves, por mecanismos de radiação de ondas longas e convecção foram eficientes em transferir calor para o meio ambiente, quando a temperatura operativa foi inferior a 28 ° C. Ao ultrapassar esta temperatura as codornas não conseguem dissipar calor para o ambiente e quando a temperatura operativa atinge 30°C torna-se nulo e o mecanismo de transferência de calor deixa de ser dissipação e passa a ser um mecanismo de ganho de calor, tornando mais um fator causador de estresse térmico. De maneira geral, conclui-se que tanto a estimativa da produção de calor metabólico quanto a determinação da transferência de calor sensível foram essenciais para a determinação do equilíbrio térmico de codornas e podem ser utilizados como ferramenta para os programas de ambiência específicos para codornas criadas em regiões tropicais ou em condições climáticas semelhantes.

The aim of this work was to study the thermal equilibrium of commercial quails in laying phase, considering the metabolic heat production and sensible heat flow between the birds and the environment. The thesis was developed in two experiments: in experiment I, the metabolic heat production in quails throughout the 24 h of the day (nictemeral cycle) in thermal comfort was evaluated. Forty female quails were used, being 20 Japanese quails (Coturnix coturnix japonica) and 20 European quails (Coturnix coturnix coturnix). The quails were evaluated in two phases: between 55 and 65 days of age and between 110 and 120 days of age. The indirect calorimetry method was used and two birds were of the each treatment analyzed simultaneously in a heat exchanger for 24 h. The environmental variables were analyzed synchronously: air temperature (ºC), atmospheric gas concentrations (carbon dioxide and oxygen %) and air partial vapor pressure (kPa). The metabolic heat production was calculated (W m2 ) considering that 76% of it is due to the oxygen consumption and 23% is due to the carbon dioxide production, in addition to ventilation (L s-1) and body surface area of the birds. The data were analyzed by the least squares method and the effects of subspecies (Japanese or European), days (1 to 20), schedules (midnight to 11:00 pm), and the interaction effect between subspecies and days, and of subspecies and schedules were analyzed. The results showed that all variables analyzed, heat production, O2 consumption, CO2 production and respiratory rate, had a significant effect (P < 0.0001). These data show that Japanese quails need less metabolic heat (58.8 W m2 ) to keep them in production, making them more efficient for egg production compared to European quails, which produce more heat (67.3 W m-2) to lay an egg per day (P < 0.0001). In relation to egg size as a proportion to body size, Japanese quails produce eggs that correspond to 5.8% of their body weight, and larger than the eggs of European quais, which produce eggs with only 4.3% of their body mass. In conclusion, the metabolic heat production in Japanese quails is lower than in European quails at thermoneutrality. When they are between 55 and 65 days old the physiology of the subspecies is different, at this age the European quails continue the growth and body mass gain, besides coinciding with the egg production, which demands that the metabolic heat production is higher than the Japanese quails. However, in the peak period of egg production with age between 110 and 120 days this rate becomes equivalent, demonstrating the high capacity of Japanese quails to produce eggs, which reinforces the need for specific nutritional and environmental programs to meet the demands of each subspecy's and for different physiological requirements according to age. The results showed that the Japanese quails are more demanding compared to European quails. In experiment II, the aim was to evaluate the sensible heat transfer in Japanese quails, considering longwave radiation and convection flows, raised in a conventional shed without environmental control. the meteorological variables - air temperature (TAR, ºC), relative humidity (RH, %) and black globe temperature (TGN, ºC); and the physiological variables - cloacal temperature (TC, ºC) and surface temperature (TS, ºC) of the quais were analyzed. The surface temperature was measured by a thermographic camera in 50 adult male and female Japanese quails, 270 days old, during 10 days, at 08:00 am and 03:00 pm. The data were analyzed by the least squares method and the effects of gender (male and female), period (morning and afternoon) and body regions (head, body and feet) were evaluated. The surface temperature of the quails was highly correlated with air temperature, mean radiant temperature and long wave radiation. All these factors influenced heat transfer. The total sensible heat flow was 64.02 W m2, the operative temperature in the morning was 22.48°C, allowing a higher gradient between the air and the quail surface, therefore a higher transfer of 82.19 W m2. In the afternoon the transfer was lower 45.70 W m2 because the operative temperature was higher 30.84°C. The comparison between genders showed that the transfer was higher in females 67.37 W m2 compared to males 60.53 W m-2. The head showed to be an important thermal window with 78.24 W m2, while the body + feet was only 56.80 W m2 in quails. Sensible heat transfer in Japanese quails is totally dependent on ambient temperature. When the operating temperature was below 28°C long wave radiation and convection flows were efficient to dissipate heat to the environment, when exceeding this temperature the quails could not dissipate heat to the environment, when it reached 30°C it became null and the mechanism becomes a way of heat gain, being one more factor to cause thermal stress. In general we conclude that both the estimation of metabolic heat production and the determination of sensible heat transfer were essential to can be used as a tool for quail ambience programs in Brazil.

Ingestive behavior and thermoregulatory responses of equine in grazing activities / Comportamento ingestivo e respostas termorregulatórias de equinos em atividades de pastejo

The objective of this article was to evaluate the main physiological responses, as well as the main patterns of ingestive behavior and physiological parameters of equines in activities grazing. Animal behavior is influenced by several factors, such as, climate, temperature, power supply, etc., thus becoming indispensable good management practices, for the animal can play to their best possible performance. The loss of heat in equines that give several ways (conduction, convection, radiation, evaporation), this occurs so that the animal can enter in their zone of thermal comfort (37.5ºC to 38.5ºC).(AU)

O objetivo deste artigo foi avaliar as principais respostas fisiológicas, bem como os principais padrões de comportamento ingestivo e parâmetros fisiológicos de equinos em atividades de pastejo. O comportamento animal recebe influência de diversos fatores, tais como, clima, temperatura, alimentação, etc., tornando-se assim indispensáveis boas práticas de manejo, para que o animal possa expressar o seu melhor desempenho possível. A perda de calor nos equinos se dar de várias maneiras (Condução, convecção, radiação, evaporação), isto ocorre para que o animal possa entrar na sua zona de conforto térmico (37,5°C a 38,5°C).(AU)

Ingestive behavior and thermoregulatory responses of equine in grazing activities / Comportamento ingestivo e respostas termorregulatórias de equinos em atividades de pastejo

The objective of this article was to evaluate the main physiological responses, as well as the main patterns of ingestive behavior and physiological parameters of equines in activities grazing. Animal behavior is influenced by several factors, such as, climate, temperature, power supply, etc., thus becoming indispensable good management practices, for the animal can play to their best possible performance. The loss of heat in equines that give several ways (conduction, convection, radiation, evaporation), this occurs so that the animal can enter in their zone of thermal comfort (37.5ºC to 38.5ºC).

O objetivo deste artigo foi avaliar as principais respostas fisiológicas, bem como os principais padrões de comportamento ingestivo e parâmetros fisiológicos de equinos em atividades de pastejo. O comportamento animal recebe influência de diversos fatores, tais como, clima, temperatura, alimentação, etc., tornando-se assim indispensáveis boas práticas de manejo, para que o animal possa expressar o seu melhor desempenho possível. A perda de calor nos equinos se dar de várias maneiras (Condução, convecção, radiação, evaporação), isto ocorre para que o animal possa entrar na sua zona de conforto térmico (37,5°C a 38,5°C).

TERMORREGULAÇÃO DA ABELHA MAMANGAVA DE GRANDE PORTE XYLOCOPA FRONTALIS NOS NEOTRÓPICOS DIANTE DAS MUDANÇAS CLIMÁTICAS

Há evidências de que as mudanças climáticas, particularmente o aquecimento global, possam alterar as condições ecológicas ideais para a sobrevivência de muitas espécies de polinizadores, especialmente as abelhas de pequeno porte que residem em ambientes temperados. No entanto, pouco se sabe como a elevação da temperatura média ambiente poderia afetar a sobrevivência de abelhas de grande porte nas regiões tropicais do planeta. No presente trabalho, investigamos o processo de termorregulação da abelha mamangava de grande porte Xylocopa frontalis, nidificando livremente em ninhos racionais que permitem a medição direta de sua temperatura corporal, ao desempenhar as diversas atividades necessárias à sua sobrevivência e reprodução em um ambiente tropical. Os resultados demonstraram que essa espécie usa estratégias de termorregulação, como a perda de calor por convecção, o resfriamento evaporativo por desidratação do néctar, e evitam forragear nos horários mais quentes do dia, para evitar o superaquecimento e prosperar na área estudada. No entanto, pode-se concluir que as áreas onde essas abelhas vivem estão no limiar das condições ecológicas necessárias à sobrevivência dessas abelhas, e mudanças climáticas futuras, dentre elas principalmente a elevação das temperaturas ambientais, podem representar um sério risco para a sobrevivência de X. frontalis e para outras espécies tropicais semelhantes.

There is evidence that climate change, particularly global warming, can alter the ideal ecological conditions for the survival of many pollinator species, especially small bees that reside in temperate environments. However, little is known how the rise in the average ambient temperature could affect the survival of large bees in tropical regions of the planet. In the present work, we investigated the thermoregulation process of the large carpenter bee Xylocopa frontalis nesting freely in rational nests that allow the direct measurement of its body temperature while performing the various activities necessary for its survival and reproduction in a tropical environment. The results showed that this species uses thermoregulation strategies such as heat loss by convection, evaporative cooling by dehydrating the nectar, and avoid foraging during the hottest times of the day, to avoid overheating and thrive in the studied area. However, it can be concluded that the areas where these bees live are on the threshold of the ecological conditions necessary for the survival of these bees and future climate changes, among them mainly the rise in environmental temperatures, can represent a serious risk for the survival of X. frontalis and other similar tropical species.

Body surface temperature in crossbred dairy cows on Triângulo Mineiro/Brazil climatic conditions / Temperatura de superfície corporal em vacas leiteiras mestiças em condições climáticas do Triângulo Mineiro/Brasil

Cattle, when in heat stress, deflect energy to increase dissipation to environment, compromising productivity. Thus, in dairy production system it is important to maintain thermal comfort to ensure homeothermy and full performance. One of the physiological measures to evaluate thermal comfort of domestic animals is hair coat surface temperature. Knowing this temperature allows the understanding whether animal performs thermal exchanges by convection through the activation of heat dissipation latent mechanisms. This study aimed to evaluate body surface temperature in crossbred dairy cows on Triângulo Mineiro climatic conditions. This was carried out at Estação Experimental Glória of Universidade Federal de Uberlândia using 53 lactating crossbred cows. Cows were housed in shaded pen for artificial insemination and after it was performed body surface temperature mensurements. Temperature was measured from body surface at four different regions: forehead, withers, groin and hock using an Instruterm infrared thermometer model TI-890. The statistical model used the region to test the effect of surface temperature comparing means by Tukeys test, with a significance level of 5%. Means and standard deviations of ambient temperature, maximum temperature, minimum temperature and relative humidity were respectively 23.96 ± 2.57C; 29.43 ± 2.50C; 17.54 ± 2.38C; and 67.18 ± 15.39%. Temper

O artigo não apresenta resumo em português.

Respiratory heat loss in Morada Nova sheep in Brazilian semi-arid regions / Perda de calor respiratório em ovinos Morada Nova no semiárido brasileiro

This study aimed to evaluate the respiratory heat loss in sheep from the equations developed for this species and its relations with meteorological variables in semi-arid regions. The respiratory heat loss (sensible and latent) was estimated through the equations in the literature for four 12-month-old male Morada Nova sheep, kept in an installation with shading of ceramic tiles and a 3-meter-high ceiling. The following environmental variables were measured: air temperature (TA), wind speed (U), relative humidity (RH) and partial vapor pressure (PP{tA}). The physiological variables measured: rectal temperature (TR) and respiratory rate (RR). Statistical analysis was performed based on regression using PROC REG procedure in SAS. The latent respiratory heat loss showed a linear and positive correlation with ambient temperature. However, the respiratory convection showed a linear and negative correlation, but with incipient values. Therefore, the latent heat loss is more important than the sensible one in the respiratory system to maintain thermoregulation of sheep in a semi-arid region of Brazil.(AU)

Este estudo teve como objetivo avaliar a perda decalor respiratório em ovinos através de equaçõesdesenvolvidas para a espécie e suas relações com as variáveismeteorológicas em região semiárida. A perda de calorrespiratório (sensível e latente) foi estimada através deequações encontradas na literatura para quatro ovinos da raçaMorada Nova com 12 meses de idade, mantidos em umainstalação com sombreamento fornecido por telhas cerâmicase pé-direito igual a 3 metros de altura. As seguintes variáveisambientais foram aferidas: temperatura do ar (TA),velocidade do vento (U), umidade relativa (UR) e da pressãoparcial de vapor (PP {tA}). As variáveis fisiológicas aferidasforam: temperatura retal (TR) e frequência respiratória (FR).A análise estatística foi realizada com base em equações deregressão utilizando o pacote PROC REG do SAS. A perdade calor latente respiratório apresentou uma relação linear epositiva com a temperatura ambiente. No entanto, aconvecção respiratória apresentou uma relação linear enegativa, mas com os valores baixos. Assim, a perda de calorlatente é mais importante do que a sensível no sistemarespiratório para manter a termorregulação de ovinos MoradaNova na região semiárida do Brasil.(AU)

Respiratory heat loss in Morada Nova sheep in Brazilian semi-arid regions / Perda de calor respiratório em ovinos Morada Nova no semiárido brasileiro

This study aimed to evaluate the respiratory heat loss in sheep from the equations developed for this species and its relations with meteorological variables in semi-arid regions. The respiratory heat loss (sensible and latent) was estimated through the equations in the literature for four 12-month-old male Morada Nova sheep, kept in an installation with shading of ceramic tiles and a 3-meter-high ceiling. The following environmental variables were measured: air temperature (TA), wind speed (U), relative humidity (RH) and partial vapor pressure (PP{tA}). The physiological variables measured: rectal temperature (TR) and respiratory rate (RR). Statistical analysis was performed based on regression using PROC REG procedure in SAS. The latent respiratory heat loss showed a linear and positive correlation with ambient temperature. However, the respiratory convection showed a linear and negative correlation, but with incipient values. Therefore, the latent heat loss is more important than the sensible one in the respiratory system to maintain thermoregulation of sheep in a semi-arid region of Brazil.

Este estudo teve como objetivo avaliar a perda decalor respiratório em ovinos através de equaçõesdesenvolvidas para a espécie e suas relações com as variáveismeteorológicas em região semiárida. A perda de calorrespiratório (sensível e latente) foi estimada através deequações encontradas na literatura para quatro ovinos da raçaMorada Nova com 12 meses de idade, mantidos em umainstalação com sombreamento fornecido por telhas cerâmicase pé-direito igual a 3 metros de altura. As seguintes variáveisambientais foram aferidas: temperatura do ar (TA),velocidade do vento (U), umidade relativa (UR) e da pressãoparcial de vapor (PP {tA}). As variáveis fisiológicas aferidasforam: temperatura retal (TR) e frequência respiratória (FR).A análise estatística foi realizada com base em equações deregressão utilizando o pacote PROC REG do SAS. A perdade calor latente respiratório apresentou uma relação linear epositiva com a temperatura ambiente. No entanto, aconvecção respiratória apresentou uma relação linear enegativa, mas com os valores baixos. Assim, a perda de calorlatente é mais importante do que a sensível no sistemarespiratório para manter a termorregulação de ovinos MoradaNova na região semiárida do Brasil.

Pattern of rectal temperature in sheep affected by foot rot / Pattern of rectal temperature in sheep affected by foot rot

Background: Circadian rhythms are biological rhythms generated by an organism or group of organisms that have an intrinsic period of 24 h. Among the many variables that exhibit circadian rhythmicity, body temperature has received considerable attention. The circadian rhythm of body temperature is a well-documented physiological phenomen. Also, it has been shown that changes in heat loss via convection and radiation are primarily caused by variations in skin blood flow, with consequent changes in skin temperature. For this reason, foot temperature assumes a great importance both as indicator of equine laminitis and foot-and-mouth disease in sheep. Particularly, the foot rot, term loosely used to describe lameness associated with the bovine foot, is characterized by acute inflammation of the skin and adjacent soft tissue of the interdigital cleft or space in which the modifications of temperature assume a great importance. In fact, the regulation of body temperature is an essential component of the process of fever, which plays an important role in an organisms response to infection and disease, and its manipulation is a standard procedure in various surgical and therapeutic procedures. In this regards, the aim of this study was to evaluate the pattern of rectal temperature (RT) both in healthy Comisana sheep and in Comisana sheep affected by foot rot.Materials, Methods & Re

Background: Circadian rhythms are biological rhythms generated by an organism or group of organisms that have an intrinsic period of 24 h. Among the many variables that exhibit circadian rhythmicity, body temperature has received considerable attention. The circadian rhythm of body temperature is a well-documented physiological phenomen. Also, it has been shown that changes in heat loss via convection and radiation are primarily caused by variations in skin blood flow, with consequent changes in skin temperature. For this reason, foot temperature assumes a great importance both as indicator of equine laminitis and foot-and-mouth disease in sheep. Particularly, the foot rot, term loosely used to describe lameness associated with the bovine foot, is characterized by acute inflammation of the skin and adjacent soft tissue of the interdigital cleft or space in which the modifications of temperature assume a great importance. In fact, the regulation of body temperature is an essential component of the process of fever, which plays an important role in an organisms response to infection and disease, and its manipulation is a standard procedure in various surgical and therapeutic procedures. In this regards, the aim of this study was to evaluate the pattern of rectal temperature (RT) both in healthy Comisana sheep and in Comisana sheep affected by foot rot.Materials, Methods & Re

Test models for estimating radiation balance in different scales for Jaboticabal, SP / Teste de modelos para estimativa de balanço de radiação em diferentes escalas para a região de Jaboticabal, SP

The net radiation (Rn) in agroecosystems is the amount of energy that is available in the environment to heating processes of living organisms, air and soil; perspiration of animals and plants; photosynthesis and water evaporation. The Rn defines the type of climate and weather conditions prevailing in a region affecting the availability and thermal water, the fundamental understanding of genotype-environment, which ultimately determine the productivity of the agricultural system. Rn usually is used in models of weather and climate studies. The sustainability and economic viability of zootechnical activity is dependent on the positive interaction between animal and environment. Environmental factors such as water, shading, thermal exchanges sensible heat (conduction, convection and radiation skin) and latent heat losses (evaporation and transpiration), conditioned by Rn, must be managed to provide the best results. The present study was conducted to develop and test models for accurate and precise radiation balance on the scales daily, monthly and seasonal ten-day for Jaboticabal - SP, due to the importance of estimates of net radiation for agricultural activities. We used daily meteorological data from weather station located in Jaboticabal, SP (coordinates: 21 14"05 "South, 48 17"09" West, 615m altitude) at Universidade Estadual Paulista "Júlio Mesquita Filho" - FCAV/UNES

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DETERMINAÇÃO DE ÁREA, VOLUME E MASSA EM ANIMAIS DE INTERESSE ZOOTÉCNICO

A fim de utilizar a modelagem tridimensional (3D) para estimar área, volume e massa, bem como avaliar o impacto dos desvios envolvidos nas equações empíricas disponíveis na literatura, em animais, foram utilizados seis ovinos Corriedale tosqueados com massa entre 10 e 105 kg e cinco bovinos Nelore com massa entre 600 a 800 kg. Os animais foram treinados utilizando os princípios de habituação e condicionamento, a fim de reduzir a reatividade dos animais. Para medição da área de superfície, utilizaram-se basicamente três procedimentos: equação empírica (EE) para cada espécie, instrumento manual de medição (IMM) e modelagem 3D do animal por fotogrametria (AR) e escaneamento com sensor kinect (AS_KS). Foi realizada uma análise de covariância, sendo a massa a covariável e uma análise de regressão não linear foi ajustada como uma função potência (alometria). Analisando as médias de área de superfície, para ovinos, em relação aos procedimentos utilizados não houve diferença entre IMM e modelos 3D, bem como entre os modelos 3D, enquanto entre IMM e EE houve diferença significativa. Para os bovinos, observou-se que os procedimentos 3D foram, em média, superiores às estimativas de área de superfície pela EE (=5%). Quando se plotou os dados de área de superfície, de ovinos, dos métodos testados em função da massa corporal, obteve-se aproximações empíricas distintas daquelas estimadas pela EE em mais de 11% para animais acima de 100kg, enquanto que para os bovinos a diferença média entre os modelos 3D e EE foi de mais de 18%. Como os ajustes das equações com IMM e por modelos 3D tiveram taxas de crescimento muito próximas e os desvios entre elas foram inferiores a 2%, constatou-se que o uso de modelos 3D foi ratificado. Quando se plotou os dados de ambas as espécies, observou-se excelentes ajustes (R²=0.99) e estimativas consistentes com aquelas obtidas pelas equações específicas para cada raça, com desvios inferiores a 3,2%. Outras relações, como volume em função da área de superfície, foram estabelecidas, resultando em aproximações consistentes quando utilizada para estimar o volume do animal. Quando se considerou o animal como um Cilindro Horizontal Padrão (CHP), sua área de superfície foi estimada, em média, 36% abaixo daquelas observadas para os modelos 3D e IMM. Por meio da simulação da transferência de calor por convecção, obteve-se uma diferença de mais 56% na taxa de convecção quando se considerou o animal como um CHP em relação aos modelos 3D e cilindro horizontal completo (CHC). Quando se relacionou as informações das imagens bidimensionais (2D) com as informações dos modelos 3D, foi possível encontrar equações para estimar área, volume e massa dos animais. Outra abordagem que ficou constatada foi a utilização de modelos 3D para avaliação em melhoramento genético, como pelo método EPMURAS. O uso de modelos 3D para estimar a área de superfície e volume em animais foi validado. O método parece ser o melhor meio para estimar a área de superfície e volume, e certamente aparece como uma ferramenta para melhorar as pesquisas envolvendo transferência de calor e massa, bem como o melhoramento genético.

In order to use three-dimensional (3D) modeling to estimate area, volume and mass, as well as to evaluate the impact of the deviations involved in the empirical equations available in the literature, in livestock, six shorn Corriedale sheep were weighed with mass between 10 and 105 kg and five Nelore cattle with mass between 600 and 800 kg. The animals were trained using the principles of habituation and conditioning in order to reduce the reactivity of the animals. For the measurement of the surface area, three procedures were used: empirical equation (EE) for each species, manual measurement instrument (IMM) and 3D animal modeling by photogrammetry (AR) and kinect sensor (AS_KS) scanning. A covariance analysis was performed, with the mass being covariable and a non-linear regression analysis was adjusted as a power function (allometry). Analyzing the surface area averages for sheep, in relation to the procedures used there was no difference between IMM and 3D models, as well as between 3D models, while between IMM and EE there was a significant difference. For cattle, it was observed that the 3D procedures were, on average, higher than the surface area estimates by EE (=5%). When data were plotted on the surface area of sheep and the methods tested for body mass, empirical approximations were obtained, different from those estimated by EE in more than 11% for animals over 100 kg, while for cattle the difference between 3D and EE models was over 18%. As the adjustments of the equations with IMM and 3D models had very close growth rates and deviations between them were lower than 2%, it was verified that the use of 3D models was ratified. When plotting the data of both species, we observed excellent adjustments (R² = 0.99) and estimates consistent with those obtained by the specific equations for each breed, with deviations lower than 3.2%. Other relationships, such as volume versus surface area, were established, resulting in consistent approximations when used to estimate the volume of the animal. When the animal was considered as a Standard Horizontal Cylinder (CHP), its surface area was estimated, on average, 36% lower than those observed for the 3D and IMM models. Simulation of the heat transfer by convection gave a difference of 56% in the convection rate when the animal was considered as a CHP in relation to the 3D models and the full horizontal cylinder (HCC). When the information of the two-dimensional images (2D) was related to the information of the 3D models, it was possible to find equations to estimate area, volume and mass of the animals. Another approach that was verified was the use of 3D models for evaluation in genetic improvement, as by the EPMURAS method. The use of 3D models to estimate surface area and volume in animals was validated. The method seems to be the best medium for estimating surface area and volume, and it certainly appears as a tool to improve research involving heat and mass transfer as well as genetic improvement.

Pattern of rectal temperature in sheep affected by foot rot

Background: Circadian rhythms are biological rhythms generated by an organism or group of organisms that have an intrinsic period of 24 h. Among the many variables that exhibit circadian rhythmicity, body temperature has received considerable attention. The circadian rhythm of body temperature is a well-documented physiological phenomen. Also, it has been shown that changes in heat loss via convection and radiation are primarily caused by variations in skin blood flow, with consequent changes in skin temperature. For this reason, foot temperature assumes a great importance both as indicator of equine laminitis and foot-and-mouth disease in sheep. Particularly, the foot rot, term loosely used to describe lameness associated with the bovine foot, is characterized by acute inflammation of the skin and adjacent soft tissue of the interdigital cleft or space in which the modifications of temperature assume a great importance. In fact, the regulation of body temperature is an essential component of the process of fever, which plays an important role in an organism's response to infection and disease, and its manipulation is a standard procedure in various surgical and therapeutic procedures. In this regards, the aim of this study was to evaluate the pattern of rectal temperature (RT) both in healthy Comisana sheep and in Comisana sheep affected by foot rot. Materials, Methods & Results: This experiment was carried out on 10 clinically healthy and not pregnant female sheep, and 10 not pregnant female sheep affected by foot rot. During the experimental period, all animals were kept under a natural photoperiod (sunrise 06:30, sunset 19:00). RT was measured every 3 h intervals for 24 consecutive hours starting at 11:00 on day 1 and ending at 11:00 on day 2. A trigonometric statistical model was applied to the average values of each time series, so as to describe the periodic phenomenon analytically, by characterizing the main rhythmic parameters according to the single cosinor procedure. Four rhythmic parameters were determined: mean level, amplitude (the difference between the peak, or trough, and the mean value of a wave), acrophase (the time at which the peak of a rhythm occurs), and robustness (strength of rhythmicity). The application of the periodic model showed a circadian rhythm of RT in healthy subjects and no circadian rhytmicity of RT was observed in ill sheep. Discussion: The analysis of the results obtained under experimental conditions used in the present study indicated the existence of a circadian periodicity of rectal temperature in healthy sheep whereas no circadian oscillations of rectal temperature were revealed in sheep affected by foot rot. A simple and coherent explanation for these pathological alterations is that the set point is elevated during the rising phase and returned to normal during the later phase. Taking together, the findings of the present study, along with those of others, emphasize the concept that RT exhibits a circadian rhythm that reflect the familiar circadian patterns of endogenous source and the existence of circadian oscillations around a set point with changes in mean body temperature and an absent rhythm when temperature is modified to a new set point, as observed in sheep affected by foot rot.

DINÂMICA TÉRMICA EM CUTIAS (Dasyprocta leporina Linnaeus, 1758) E PREÁS (Galea spixii Wagler, 1831) EM AMBIENTE SEMIÁRIDO NEOTROPICAL MOSSORÓ-RN 2016

Como a termorregulação de cutias (Dasyprocta leporina Linneus, 1758) e preás (Galea spixii Wagler, 1831) em um ambiente semiárido permanece desconhecida, o presente trabalho objetivou determinar a termólise evaporativa e a transferência de calor por radiação e convecção. Foram utilizadas 20 cutias e 28 preás em experimentos distintos. As cutias foram submetidas a oito dias de amostragem, sendo as coletas de dados realizadas em cinco horários (7h00, 9h00, 11h00, 14h00 e 16h00). Cada preá foi submetido a três dias de amostragem, com coletas de dados realizadas em intervalos de uma hora, das 6h00 às 13h00. O ambiente térmico foi monitorado em cada horário de coleta. A temperatura da superfície corporal foi mensurada por termografia infravermelha. As regiões corporais consideradas nos termogramas das cutias foram: focinho, olhos, orelhas, corpo, membros torácicos e pélvicos. Nos termogramas dos preás foram consideradas, além daquelas mencionadas para cutias, as vibrissas e as perioculares. A termólise evaporativa foi determinada por calorimetria. As orelhas (13,10±1,17 W m-2) e os membros pélvicos (11,19±1,17 W m-2) foram as principais regiões envolvidas na perda de calor por radiação em cutias, funcionando como janelas térmicas. A termólise por radiação em preás foi mais elevada nas regiões perioculares (45,23±0,81 W m-2), seguida dos olhos (41,41±0,81 W m-2), orelhas (31,56±0,80 W m-2) e vibrissas (27,03±0,80 W m-2). As temperaturas das regiões perioculares mostraram ser valorosas preditoras da temperatura retal de preás, exibindo coeficiente de correlação de 0,61. A termólise convectiva em cutias foi mais intensa no corpo e membros pélvicos em todos os horários. Nos preás, a transferência de calor por convecção foi irrisória (0,54±0,56 W m-2). A termólise evaporativa em cutias (52,53±1,64 W m-2) e preás (143,69±1,37 W m-2) foi mais intensa no horário com maior temperatura atmosférica. Assim, observamos que tanto mecanismos não-evaporativos quanto evaporativos são importantes para a manutenção da homeotermia de cutias e preás em ambiente quente. Estes roedores utilizam regiões corporais especializadas na transferência de calor, que correspondem às janelas térmicas.

Because the thermoregulation of red-rumped agouti (Dasyprocta leporina Linneus, 1758) and Spixs yellow-toothed cavy (Galea spixii Wagler, 1831) facing a semiarid environment remain unknown, this study aimed to determine the evaporative heat loss and heat exchanges by radiation and convection. Twenty red-rumped agoutis and twenty-eight Spixs yellow-toothed cavies were used in different experiments. Red-rumped agoutis were subjected to eight samplings days, and the data collection was performed in five times (7h00, 9h00, 11h00, 14h00 and 16h00). Each Spixs yellow-toothed cavy was subjected to three sampling days, with data collection performed at hourly intervals, from 6h00 to 13h00. The thermal environment was monitored in each data collection. The body surface temperature was measured by infrared thermography. The body regions considered in the thermograms of red-rumped agoutis were nose, eyes, pinna, body, fore and hindlimbs. In addition to those mentioned for agoutis, thermograms of Spixs yellow-toothed cavies considered the vibrissae and periocular regions. Evaporative heat loss was determined by calorimetry. The pinna (13.10±1.17 W m-2) and hindlimbs (11.19±1.17 W m-2) of the agoutis were the main regions involved in heat loss by radiation, working as thermal windows. The radiation was higher in the periocular regions (45.23±0.81 W m-2), followed by the eyes surface (41.41±0.81 W m-2), pinna (31.56±0.80 W m-2) and vibrissae (27.03±0.80 W m-2). The periocular temperatures proved to be a valuable predictor of rectal temperature of the cavies, showing a correlation coefficient of 0.61. The convection in agoutis was more intense in the body and hindlimbs at all day times. In cavies, the convection was insignificant (0.54±0.56 W m-2). Evaporative heat loss in agoutis (52.53±1.64 W m-2) and cavies (143.69±1.37 W m-2) was more intense when the atmospheric temperature was higher. Thus, we observe that both non-evaporative and evaporative mechanisms are important for the maintenance of homeothermy in red-rumped agouti and Spixs yellow-toothed cavy in a hot environment. These rodents use specialized body regions in the heat transfer, the thermal windows.

ESPIROMETRIA NA AVALIAÇÃO DO SISTEMA RESPIRATÓRIO DE RUMINANTES EM AMBIENTE TROPICAL

Objetivou-se a partir deste estudo avaliar a dinâmica das trocas térmicas ocorridas no trato respiratório de animais de interesse zootécnico (bovinos e caprinos), em ambiente tropical, utilizando a técnica de espirometria de fluxo contínuo com uso de máscara facial. Foram realizados quatro estudos de espirometria e calorimetria indireta com três raças da espécie bovina, Nelore, Guzerá e Jersey e uma da espécie caprina da raça Anglo-nubiana. A realização da espirometria e da calorimetria indireta foi feita por meio de uso de máscara facial ajustada ao focinho do animal. A produção de calor metabólico (qMET), ventilação (VE), frequência respiratória (FR), volume respiratório corrente (VRC) e produção e consumo de CO2 (VCO2) e O2 (VO2), respectivamente, foram mensuradas simultaneamente, além das trocas de calor do animal por evaporação e convecção pelo trato respiratório com o meio ambiente. Avaliações de espirometria e calorimetria indireta com utilização de máscara facial em animais de produção em ambiente natural mostraram-se eficientes para as espécies estudadas uma função não linear entre VRC, VE, VO2 e FR por unidade de peso e peso corporal foi encontrada; animais de menor peso corporal apresentam maiores VRC, VE, VO2 e FR e consequentemente uma maior produção de calor metabólico por unidade de peso corporal do que animais maiores. Em faixas de temperatura do ar de 22 a 36 °C os animais Guzerá, Nelore, Jersey e Anglo Nubianas não tem um aumento significativo nas funções respiratórias porém, o volume de CH4 apresenta uma relação inversa com o aumento da temperatura do ar. As perdas de calor pelo trato respiratório por evaporação aumentaram com o aumento da temperatura do ar, sendo essa a principal via de perda de calor no trato respiratório. Modelos de regressão apresentados para estimar a evaporação respiratória em bovinos da raça Guzerá, Nelore, Jersey e caprino da raça Anglo Nubiana utilizando parâmetros ambientais e fisiológicos se mostraram bem eficientes nestas condições

In order to study the respiratory physiology and the dynamics of the heat exchange occurred in the respiratory tract of livestock interest of animals in tropical environment using a continuous flow of spirometry technique with use of facial mask. Four studies of spirometry and indirect calorimetry were performed in two species of livestock interest animals, and these three races of bovine animals, Nellore, Guzerat and Jersey and a goats Anglo-Nubian breed. The spirometry and indirect calorimetry was performed by use of the face mask adjust to the animals muzzle. The metabolic heat production (q"MET), ventilation (VE), respiratory rate (RR), tidal volume (VT) and production and consumption of CO2 (VCO2) and O2 (VO2), respectively, were measured simultaneously, as well of the animal's heat exchange by convection and by evaporation with the respiratory tract environment. Spirometry and indirect calorimetry techniques with use of facial masks in livestock animals in a natural environment were effective for the species studied. A nonlinear function between VRC, VE, VO2 and FR per unit weight as function of body weight was found and the lighter animals had a higher VRC, VE, VO2 and FR and thus greater metabolic heat production per unit weight than largest animals. In air temperature between 22-36 °C the Guzerat, Nellore, Jersey and Anglo Nubian has no significant increase respiratory function, but the volume of CH4 has an inverse relation with air temperature. Also heat losses the respiratory tract by evaporation increased with increasing air temperature, and this is the main heat loss through the respiratory tract. Regression models presented to estimate the respiratory evaporation in cattle Guzerat, Nellore, Jersey and the Anglo Nubian goat using environmental and physiological parameters were well efficient in these conditions