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)

Behavioral, productive, and reproductive aspects of the water buffalo in Mexico

Water buffalo (Bubalus bubalis) production in Mexico has generated particular interest in understanding the bases of the development of this species. As a result, alliances have emerged between scientific, governmental, industrial, and productive sectors and other organisms involved with this species nationally and internationally. We must recognize that thanks to specific anatomical characteristics, water buffaloes present a low incidence of complications during calving, though they are not exempt from obstetric and perinatological problems that can end in morbidity and mortality for mother and/or offspring, with losses for both branches of dual-purpose production systems: calves-milk and meat, and draft animals. This article analyzes scientific advances related to water buffalo production in Mexico, including productivity, thermoregulation, behavior, and physiology, and key subthemes like obstetric and perinatological handling, imprinting, milking, and dual-purpose production systems. It highlights features inherent to milk production and the neurophysiological and metabolic processes involved in obtaining meat and milk. Finally, it presents a brief overview of current legislation and summarizes key areas of opportunity.(AU)

Key points for the thermal comfort of water buffaloes in Eastern Amazon / Pontos-chave do conforto térmico de bubalinos na Amazônia Oriental

ABSTRACT: This study presented relevant aspects about the Amazonian environment and how it impacts the thermal comfort of domestic buffaloes (Bubalus bubalis) raised in the Eastern Amazon. Furthermore, strategies for monitoring and mitigating animal heat stress are presented, based on research results with the species. Although domestic buffaloes are considered adaptable animals, exposure to intense solar radiation causes thermal discomfort. This condition is expressed in biophysical indicators, in metabolic, endocrine, behavioral responses, and in body thermographic patterns. Therefore, the biometeorological monitoring of production is crucial to support decision-making regarding environmental management strategies, genetic selection of thermotolerant individuals, and increase in animal welfare. Lastly, the use of silvopastoral systems can help to provide higher thermal comfort, which is a condition that directly impacts the productivity of milk and meat buffaloes when they are raised in tropical regions, such as in the Eastern Amazon.

RESUMO: Objetivou-se apresentar aspectos relevantes sobre o ambiente amazônico e como este impacta no conforto térmico de búfalos domésticos (Bubalus bubalis) criados na Amazônia Oriental. Adicionalmente, são apresentadas estratégias para monitoramento e mitigação do estresse térmico animal, a partir de resultados de pesquisa com a espécie. Apesar dos búfalos domésticos serem considerados animais adaptáveis, a exposição à intensa radiação solar provoca desconforto térmico. Essa condição é expressa em indicadores biofísicos, nas respostas metabólicas, endócrinas, comportamentais e nos padrões termográficos corporais. Assim, o monitoramento biometeorológico da produção é crucial para subsidiar tomadas de decisão em relação a estratégias de manejo ambiental, seleção genética de indivíduos termotolerantes e incremento do bem-estar animal. Por fim, o uso de sistemas silvipastoris pode auxiliar na oferta de maior conforto térmico, que é uma condição que impacta diretamente na produtividade de bubalinos de leite e carne, quando estes são criados em regiões tropicais, como na Amazônia Oriental.

Key points for the thermal comfort of water buffaloes in Eastern Amazon / Pontos-chave do conforto térmico de bubalinos na Amazônia Oriental

This study presented relevant aspects about the Amazonian environment and how it impacts the thermal comfort of domestic buffaloes (Bubalus bubalis) raised in the Eastern Amazon. Furthermore, strategies for monitoring and mitigating animal heat stress are presented, based on research results with the species. Although domestic buffaloes are considered adaptable animals, exposure to intense solar radiation causes thermal discomfort. This condition is expressed in biophysical indicators, in metabolic, endocrine, behavioral responses, and in body thermographic patterns. Therefore, the biometeorological monitoring of production is crucial to support decision-making regarding environmental management strategies, genetic selection of thermotolerant individuals, and increase in animal welfare. Lastly, the use of silvopastoral systems can help to provide higher thermal comfort, which is a condition that directly impacts the productivity of milk and meat buffaloes when they are raised in tropical regions, such as in the Eastern Amazon.

Objetivou-se apresentar aspectos relevantes sobre o ambiente amazônico e como este impacta no conforto térmico de búfalos domésticos (Bubalus bubalis) criados na Amazônia Oriental. Adicionalmente, são apresentadas estratégias para monitoramento e mitigação do estresse térmico animal, a partir de resultados de pesquisa com a espécie. Apesar dos búfalos domésticos serem considerados animais adaptáveis, a exposição à intensa radiação solar provoca desconforto térmico. Essa condição é expressa em indicadores biofísicos, nas respostas metabólicas, endócrinas, comportamentais e nos padrões termográficos corporais. Assim, o monitoramento biometeorológico da produção é crucial para subsidiar tomadas de decisão em relação a estratégias de manejo ambiental, seleção genética de indivíduos termotolerantes e incremento do bem-estar animal. Por fim, o uso de sistemas silvipastoris pode auxiliar na oferta de maior conforto térmico, que é uma condição que impacta diretamente na produtividade de bubalinos de leite e carne, quando estes são criados em regiões tropicais, como na Amazônia Oriental.

Foraging Oxaea flavescens bees as a function of the dynamics of abiotic factors and food resource availability from Styrax camporum flowers

We examined the abiotic factors and co-specific competition for food resources that regulate the foraging activity of Oxaea flavescens bees on Styrax camporum flowers. Foraging records were gathered during 20 min. periods at the beginning of each hour between 05:00h and 18:00h during three nonconsecutive days. Pearson correlation and linear regression tests indicated that the foraging activity of O. flavescens was associated with abiotic factors during the day. O. flavescens represented 89.9% of the observed foraging visits to S. camporum flowers. On the first day of sampling, when environmental conditions were stressful, the foraging activity of O. flavescens was significantly negatively correlated with light intensity, wind speed, and temperature, and positively correlated with relative humidity. Under those conditions, optimal foraging was little affected by the availability of floral resources. On the second and third days, however, when environmental conditions were more favorable, the principal limiting factor of O. flavescens foraging activity was nectar depletion. The maximum peak of foraging under those conditions occurred before the abiotic conditions were fully favorable, however, as the eventual depletion of floral resources resulted in unfavorable cost/benefit implications for foraging during the otherwise most adequate daylight period.(AU)

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.

Atualização sobre o estresse térmico testicular / Updates on testicular heat stress

Os testículos, são mantidos no escroto a uma temperatura ~3-5°C abaixo da corporal. Quando a temperatura das gônadas se eleva, instala-se um quadro de estresse térmico (ET) testicular. O ET afeta a espermatogênese, e observam-se, já na primeira semana pós-ET, impactos na cinética, concentração e morfologia espermática. Classicamente, tais efeitos eram creditados à incapacidade da circulação local de atender ao aumento do metabolismo testicular devido ao aumento da temperatura local. Contudo, estudos recentes demonstraram que a hipóxia não era a causa da degeneração testicular. Atualmente, credita-se os efeitos deletérios do ET ao aumento local das espécies reativas de O2. Nesta situação, apesar da ativação de mecanismos antioxidantes (aumento das HSP e GPX1) e de proteção do DNA (aumento da P53), estes não são suficientes, sendo desencadeada a apoptose. Os efeitos deletérios do ET testicular podem ser mitigados pela melatonina, que pode ser tanto administrada aos animais ou adicionada ao sêmen para que desencadeie seus efeitos protetores.(AU)

The testes are kept in the scrotum at a ~3-5°C below body core temperature. When the temperature of the gonads increases, a process called heat stress (HS) takes place. The HS impairs spermatogenesis, and in the first week post-HS, impacts in sperm kinetics, concentration, and morphology are observed. Classically, such effects were credited to the incapacity of the local circulation to sustain the higher testicular metabolism due to the increased temperature. However, recent studies demonstrated that it was not the cause of testicular degeneration. The novel perspective credits the deleterious impacts of the HS to the local increase of the reactive oxygen species. Importantly, although there's an activation of antioxidant defenses (increase in HSP and GPX1) and DNA protection (increase in P53), such mechanisms are not sufficient, unfolding the apoptotic cascade. Lastly, some of the negative effects of HS can be mitigated by melatonin, which can either be given to the animals or added to the sperm to exert its protective effects.(AU)

Correlations between body surface, rectal temperatures and the average weight of broilers / Correlações entre as temperaturas da superfície corpórea e retal e os pesos médios de frangos de corte

Body temperature is one of the indicators of broilers' susceptibility to thermal stress, which can compromise performance. This study aimed to evaluate correlations between both the surface and rectal temperatures, besides the average weight of broilers assessed in different ages. Temperatures of broilers' back, breast, and rectum were evaluated, besides the average weight of broilers at 7, 14, 21, and 35 days old. One hundred birds were assessed for each evaluation age, and the variables were submitted to Pearson's correlation analyses. The rectal temperature had a correlation with the breast one when the birds were evaluated at7 and 14 days old. The average weight correlated only with rectal and breast temperatures at 14 and 21 days old, respectively. The correlations between the temperatures were weak or insignificant in most of the studied ages. Therefore, the skin temperature is not a suitable parameter for measuring broilers' temperature compared to the rectal one, so the use of infrared thermometer did not prove to be a useful strategy to estimate the internal temperature of broilers.

A temperatura corporal é um dos indicadores de suscetibilidade dos frangos de corte ao estresse térmico, o que pode comprometer o desempenho. Este estudo teve como objetivo avaliar as correlações entre as temperaturas superficial e retal, além do peso médio de frangos de corte avaliados em diferentes idades. Foram avaliadas as temperaturas do dorso, peito e reto das aves, além do peso médio das aves aos 7, 14, 21 e 35 dias de idade. Cem aves foram avaliadas para cada idade de avaliação, e as variáveis foram submetidas à análise de correlação de Pearson. A temperatura retal apresentou correlação com a do peito quando as aves foram avaliadas aos 7 e 14 dias de idade. O peso médio correlacionou-se apenas com as temperaturas retal e do peito aos 14 e 21 dias deidade, respectivamente. As correlações entre as temperaturas foram fracas ou insignificantes na maioria das idades estudadas. Portanto, a temperatura da pele não é um parâmetro adequado para medir a temperatura de frangos de corte em comparação com a retal, de modo que o uso de termômetro infravermelho não se mostrou uma estratégia útil para estimar a temperatura interna de frangos de corte.

Self-made home: how and where does the anuran Rhinella dorbignyi build its retreat sites / Com as próprias patas: Como e onde o Sapinho-de-Jardim Rhinella dorbignyi constrói seus abrigos

In this study, we observed that burrows of Rhinella dorbignyi (Duméril & Bibron, 1841) are distributed in a non-random manner in the habitat, suggesting a microhabitat selection for digging. This conclusion was based on a characterization of 36 burrows and surrounding micro-habitat. We established a 1 m x 1 m quadrat with the burrow in its central point (n=36) to measure the percentage (density) and the average heights of grasses, herbs, and shrubs. All measurements were repeated in two unused quadrats (without burrows) to evaluate the available microhabitat (n=72). The burrows are built in specific areas of the habitat with a higher percentage of grass, taller herbs, lower density of shrubs and low shaded sites than the founded at control sites. Based on three-dimensional models of the interior of the burrow (n=15), we observed that all of them were constructed with an elliptical opening that opens into a narrow channel perpendicular to the ground. Channels had a mean maximum diameter of 38 mm and a mean minimum diameter of 18 mm. The mean length of the burrows is 182 mm, and the mean volume is 95 mL.

Neste estudo, observamos que tocas de Rhinella dorbignyi (Duméril & Bibron, 1841) são distribuídas de uma forma não-aleatória no habitat, sugerindo que esta espécie seleciona sítios para cavá-las. Esta conclusão foi baseada em uma caracterização de 36 tocas e do micro-habitat que as cerca. Estabelecemos um quadrante de 1 m x 1 m com a toca como seu ponto central (n=36) para medir a porcentagem (densidade) e a altura média de gramíneas, plantas herbáceas e arbustos. Todas as medidas foram repetidas em dois quadrantes não utilizados (sem tocas), para avaliar o micro-habitat disponível ao anfíbio (n=72). As tocas são construídas em áreas específicas do habitat com maior porcentagem de gramíneas, ervas mais altas, menos arbustos presentes e pouca área sombreada. Baseado em modelos tridimensionais do interior das tocas (n=15), observamos que todas elas são construídas com uma abertura elíptica que se abre para um canal estreito, perpendicular ao chão. Os canais têm diâmetro máximo médio de 38 mm e diâmetro mínimo médio de 18 mm. O comprimento médio das tocas é de 182 mm, e o volume médio é de 95 mL.

Microhabitat selection of the poorly known lizard Tropidurus lagunablanca (Squamata: Tropiduridae) in the Pantanal, Brazil

Abstract Understanding how different environmental factors influence species occurrence is a key issue to address the study of natural populations. However, there is a lack of knowledge on how local traits influence the microhabitat use of tropical arboreal lizards. Here, we investigated the microhabitat selection of the poorly known lizard Tropidurus lagunablanca (Squamata: Tropiduridae) and evaluated how environmental microhabitat features influence animals presence. We used a Resource Selection Function approach, in a case/control design where we analyzed the effect of substrate temperature and trees diameter at breast height (DBH) in the probability of presence of lizards using mixed Conditional Logistic Regression. We found that T. lagunablanca uses trees with DBH from 0.40 m to 4 m and substrate temperatures ranging from 25.9°C to 42°C. Moreover, we showed that thickness of the trees and substrate temperatures significantly increased the probability of presence of T. lagunablanca individuals, being the probability of presence higher than 50% for trees up to 1.5 m DBH and temperature of substrate up to 37.5°C. Our study probed that T. lagunablanca individuals choose trees non-randomly, selecting thicker and warmer tree trunks. This information advances the knowledge of the spatial ecology of Neotropical arboreal lizards and is relevant for conservation, putting an emphasis on preserving native vegetation in the Pantanal.

Microhabitat selection of the poorly known lizard Tropidurus lagunablanca (Squamata: Tropiduridae) in the Pantanal, Brazil

Abstract Understanding how different environmental factors influence species occurrence is a key issue to address the study of natural populations. However, there is a lack of knowledge on how local traits influence the microhabitat use of tropical arboreal lizards. Here, we investigated the microhabitat selection of the poorly known lizard Tropidurus lagunablanca (Squamata: Tropiduridae) and evaluated how environmental microhabitat features influence animal's presence. We used a Resource Selection Function approach, in a case/control design where we analyzed the effect of substrate temperature and tree's diameter at breast height (DBH) in the probability of presence of lizards using mixed Conditional Logistic Regression. We found that T. lagunablanca uses trees with DBH from 0.40 m to 4 m and substrate temperatures ranging from 25.9°C to 42°C. Moreover, we showed that thickness of the trees and substrate temperatures significantly increased the probability of presence of T. lagunablanca individuals, being the probability of presence higher than 50% for trees up to 1.5 m DBH and temperature of substrate up to 37.5°C. Our study probed that T. lagunablanca individuals choose trees non-randomly, selecting thicker and warmer tree trunks. This information advances the knowledge of the spatial ecology of Neotropical arboreal lizards and is relevant for conservation, putting an emphasis on preserving native vegetation in the Pantanal.

Microhabitat selection of the poorly known lizard Tropidurus lagunablanca(Squamata: Tropiduridae) in the Pantanal, Brazil

Understanding how different environmental factors influence species occurrence is a key issue to address the study of natural populations. However, there is a lack of knowledge on how local traits influence the microhabitat use of tropical arboreal lizards. Here, we investigated the microhabitat selection of the poorly known lizard Tropidurus lagunablanca(Squamata: Tropiduridae) and evaluated how environmental microhabitat features influence animals presence. We used a Resource Selection Function approach, in a case/control design where we analyzed the effect of substrate temperature and trees diameter at breast height (DBH) in the probability of presence of lizards using mixed Conditional Logistic Regression. We found that T. lagunablanca uses trees with DBH from 0.40 m to 4 m and substrate temperatures ranging from 25.9°C to 42°C. Moreover, we showed that thickness of the trees and substrate temperatures significantly increased the probability of presence of T. lagunablanca individuals, being the probability of presence higher than 50% for trees up to 1.5 m DBH and temperature of substrate up to 37.5°C. Our study probed that T. lagunablanca individuals choose trees non-randomly, selecting thicker and warmer tree trunks. This information advances the knowledge of the spatial ecology of Neotropical arboreal lizards and is relevant for conservation, putting an emphasis on preserving native vegetation in the Pantanal.(AU)

Influence of season and external morphology on thermal comfort and physiological responses in bulls from two breeds adapted to a subtropical climate / Influência da estação e da morfologia externa no conforto térmico e respostas fisiológicas em touros de duas raças adaptadas a um clima subtropical

Animals in subtropical regions can be exposed to periods of thermal stress. Locally adapted breeds are especially important in this context, but these have little information available in their natural environments. The aim of this study was to assess whether season affects thermal comfort and physiological responses to increased temperatures of two breeds of bulls in a subtropical climate. Four Angus and four Crioulo Lageano bulls were used in this study. Body and testicles measurements, skin pigmentation and thickness, hair number, length and pigmentation, respiratory rate, panting score, rectal temperature and haematological profile were recorded on three occasions in summer and winter, morning and afternoon. The surface temperature of the flank, eye and scrotum were obtained by infrared thermography. Hair coat colour was determined by CIELAB method. Thermal comfort indexes were calculated from meteorological data. Statistical analysis included analyses of variance, correlations and a partial least squares regression in determining which traits were the most important in thermal adaptability. External morphology of the bulls was important for explaining physiological changes in both seasons, but their contribution was greater in summer. Bulls experienced moderate heat stress in summer, which led to significant physiological responses, which were more pronounced in Angus bulls. The main differences in thermal adaptation found between breeds were the hair coat characteristics and respiratory rate. Despite using different mechanisms to cope with environmental challenges, all bulls were able to maintain optimal testicular thermoregulation as well as systemic normothermia throughout the seasons, showing good adaptation to the climate conditions.(AU)

Animais em regiões subtropicais podem ser expostos ao estresse térmico. As raças localmente adaptadas são especialmente importantes nesse contexto, mas possuem pouca informação disponível em seus ambientes naturais. O objetivo deste estudo foi avaliar se a estação afeta o conforto térmico e as respostas fisiológicas ao aumento da temperatura de duas raças de touros em clima subtropical. Quatro touros Angus e quatro Crioulo Lageano foram utilizados neste estudo. As medidas do corpo e testículos, pigmentação e espessura da pele, número, comprimento e pigmentação de pêlos, frequência respiratória, escore ofegante, temperatura retal e perfil hematológico foram registradas no verão e inverno, manhã e tarde. A temperatura da superfície do flanco, olho e escroto foi obtida por termografia infravermelho. Os índices de conforto térmico foram calculados a partir de dados meteorológicos. A análise estatística incluiu análises de variância, correlações e uma regressão parcial de mínimos quadrados para determinar quais características foram as mais importantes na adaptabilidade térmica. A morfologia externa dos touros foi importante para explicar as mudanças fisiológicas nas duas estações, mas sua contribuição foi maior no verão. Os touros sofreram estresse térmico moderado no verão, o que levou a respostas fisiológicas significativas, que foram mais pronunciadas na Angus. As principais diferenças de adaptação térmica encontradas entre as raças foram as características do pêlo e a frequência respiratória. Apesar de usar diferentes mecanismos para lidar com os desafios ambientais, todos os touros foram capazes de manter a termorregulação testicular ideal e a normotermia, mostrando boa adaptação às condições climáticas.(AU)

Influence of season and external morphology on thermal comfort and physiological responses in bulls from two breeds adapted to a subtropical climate / Influência da estação e da morfologia externa no conforto térmico e respostas fisiológicas em touros de duas raças adaptadas a um clima subtropical

Animals in subtropical regions can be exposed to periods of thermal stress. Locally adapted breeds are especially important in this context, but these have little information available in their natural environments. The aim of this study was to assess whether season affects thermal comfort and physiological responses to increased temperatures of two breeds of bulls in a subtropical climate. Four Angus and four Crioulo Lageano bulls were used in this study. Body and testicles measurements, skin pigmentation and thickness, hair number, length and pigmentation, respiratory rate, panting score, rectal temperature and haematological profile were recorded on three occasions in summer and winter, morning and afternoon. The surface temperature of the flank, eye and scrotum were obtained by infrared thermography. Hair coat colour was determined by CIELAB method. Thermal comfort indexes were calculated from meteorological data. Statistical analysis included analyses of variance, correlations and a partial least squares regression in determining which traits were the most important in thermal adaptability. External morphology of the bulls was important for explaining physiological changes in both seasons, but their contribution was greater in summer. Bulls experienced moderate heat stress in summer, which led to significant physiological responses, which were more pronounced in Angus bulls. The main differences in thermal adaptation found between breeds were the hair coat characteristics and respiratory rate. Despite using different mechanisms to cope with environmental challenges, all bulls were able to maintain optimal testicular thermoregulation as well as systemic normothermia throughout the seasons, showing good adaptation to the climate conditions.

Animais em regiões subtropicais podem ser expostos ao estresse térmico. As raças localmente adaptadas são especialmente importantes nesse contexto, mas possuem pouca informação disponível em seus ambientes naturais. O objetivo deste estudo foi avaliar se a estação afeta o conforto térmico e as respostas fisiológicas ao aumento da temperatura de duas raças de touros em clima subtropical. Quatro touros Angus e quatro Crioulo Lageano foram utilizados neste estudo. As medidas do corpo e testículos, pigmentação e espessura da pele, número, comprimento e pigmentação de pêlos, frequência respiratória, escore ofegante, temperatura retal e perfil hematológico foram registradas no verão e inverno, manhã e tarde. A temperatura da superfície do flanco, olho e escroto foi obtida por termografia infravermelho. Os índices de conforto térmico foram calculados a partir de dados meteorológicos. A análise estatística incluiu análises de variância, correlações e uma regressão parcial de mínimos quadrados para determinar quais características foram as mais importantes na adaptabilidade térmica. A morfologia externa dos touros foi importante para explicar as mudanças fisiológicas nas duas estações, mas sua contribuição foi maior no verão. Os touros sofreram estresse térmico moderado no verão, o que levou a respostas fisiológicas significativas, que foram mais pronunciadas na Angus. As principais diferenças de adaptação térmica encontradas entre as raças foram as características do pêlo e a frequência respiratória. Apesar de usar diferentes mecanismos para lidar com os desafios ambientais, todos os touros foram capazes de manter a termorregulação testicular ideal e a normotermia, mostrando boa adaptação às condições climáticas.

Influence of season and external morphology on thermal comfort and physiological responses in bulls from two breeds adapted to a subtropical climate

ABSTRACT Animals in subtropical regions can be exposed to periods of thermal stress. Locally adapted breeds are especially important in this context, but these have little information available in their natural environments. The aim of this study was to assess whether season affects thermal comfort and physiological responses to increased temperatures of two breeds of bulls in a subtropical climate. Four Angus and four Crioulo Lageano bulls were used in this study. Body and testicles measurements, skin pigmentation and thickness, hair number, length and pigmentation, respiratory rate, panting score, rectal temperature and haematological profile were recorded on three occasions in summer and winter, morning and afternoon. The surface temperature of the flank, eye and scrotum were obtained by infrared thermography. Hair coat colour was determined by CIELAB method. Thermal comfort indexes were calculated from meteorological data. Statistical analysis included analyses of variance, correlations and a partial least squares regression in determining which traits were the most important in thermal adaptability. External morphology of the bulls was important for explaining physiological changes in both seasons, but their contribution was greater in summer. Bulls experienced moderate heat stress in summer, which led to significant physiological responses, which were more pronounced in Angus bulls. The main differences in thermal adaptation found between breeds were the hair coat characteristics and respiratory rate. Despite using different mechanisms to cope with environmental challenges, all bulls were able to maintain optimal testicular thermoregulation as well as systemic normothermia throughout the seasons, showing good adaptation to the climate conditions.

RESUMO Animais em regiões subtropicais podem ser expostos ao estresse térmico. As raças localmente adaptadas são especialmente importantes nesse contexto, mas possuem pouca informação disponível em seus ambientes naturais. O objetivo deste estudo foi avaliar se a estação afeta o conforto térmico e as respostas fisiológicas ao aumento da temperatura de duas raças de touros em clima subtropical. Quatro touros Angus e quatro Crioulo Lageano foram utilizados neste estudo. As medidas do corpo e testículos, pigmentação e espessura da pele, número, comprimento e pigmentação de pêlos, frequência respiratória, escore ofegante, temperatura retal e perfil hematológico foram registradas no verão e inverno, manhã e tarde. A temperatura da superfície do flanco, olho e escroto foi obtida por termografia infravermelho. Os índices de conforto térmico foram calculados a partir de dados meteorológicos. A análise estatística incluiu análises de variância, correlações e uma regressão parcial de mínimos quadrados para determinar quais características foram as mais importantes na adaptabilidade térmica. A morfologia externa dos touros foi importante para explicar as mudanças fisiológicas nas duas estações, mas sua contribuição foi maior no verão. Os touros sofreram estresse térmico moderado no verão, o que levou a respostas fisiológicas significativas, que foram mais pronunciadas na Angus. As principais diferenças de adaptação térmica encontradas entre as raças foram as características do pêlo e a frequência respiratória. Apesar de usar diferentes mecanismos para lidar com os desafios ambientais, todos os touros foram capazes de manter a termorregulação testicular ideal e a normotermia, mostrando boa adaptação às condições climáticas.

Estresse calórico e reprodução em ovinos: fundamentos e perspectivas tecnológicas / Heat stress on sheep reproduction: fundamentals and technological perspectives

A ovinocultura é uma importante atividade que produz proteínas de alto valor biológico, mas seus ganhos podem ser reduzidos em função do estresse ambiental. Isso reforça a importância de se estudar a relação entre o ambiente térmico e o animal, identificando animais mais adaptados e férteis, e melhores práticas de manejo. O ovino (Ovis aries) é um animal homeotérmico, que mantem sua temperatura corporal em equilíbrio dinâmico. Quando em estresse calórico, os ovinos usam mecanismos sensíveis e latentes para dissipar o calor acumulado, com destaque para o redirecionamento do fluxo sanguíneo, a ofegação e a sudorese. O escroto desempenha importante crucial na termorregulação dos testículos, os quais precisam funcionar sob em até 6,0oC abaixo da temperatura interna corpórea. A hipertermia testicular compromete a espermatogênese, reduz a concentração seminal, a motilidade progressiva e a viabilidade espermática. Ainda, leva a aumento dos defeitos morfológicos espermáticos, na produção de espécies reativas de oxigênio e na fragmentação do DNA espermático, diminuindo a capacidade fecundante. Tecnologias disruptivas para monitoramento do ambiente de produção, da termorregulação e do bem-estar dos animais já são realidade e se encontram em expansão, favorecendo a tomada de decisões em tempo real e o desempenho reprodutivo dos ovinos.

Sheep farming is a relevant activity that provides proteins of high biological value, but its gains can be reduced due to environmental stress. This reinforces the importance of studying the relationship between the thermal environment and the animal, identifying more adapted and fertile animals, and better management practices. Sheep (Ovis aries) are homeothermic animals and thus maintain their body temperature in a state of dynamic balance. Under heat stress, sheep dissipate accumulated heat through sensitive and latent mechanisms, primarily using redirection of blood flow, panting and sweating. The scrotum plays a crucial role in the thermoregulation of the testicles, which need to be maintained up to 6.0oC below the body core temperature. Testicular hyperthermia impairs spermatogenesis, reduces seminal concentration, progressive motility and sperm viability. Furthermore, it leads to an increase in sperm morphological defects, in the production of reactive oxygen species, and in sperm DNA fragmentation, reducing the fertilizing capacity. Disruptive technologies for monitoring the production systems, animal thermoregulation and welfare are already a reality and are expanding, favoring realtime decision making and the reproductive performance of sheep.

Pathogenesis and mitigation of the deleterious effects of heat stress on bull reproduction / Patogênese e mitigação dos efeitos deletérios do estresse térmico na reprodução de touros

Bull testes must be 2 to 6 0C below body temperature for morphologically normal, motile and fertile sperm. Scrotal/testicular thermoregulation is complex, including a coiled testicular artery, surrounded by the venous pampiniform plexus comprising the testicular vascular cone, a counter-current heat exchanger. In addition, heat radiation from the scrotum, sweating, complementary arterial blood supplies, and temperature gradients in the scrotum and testes all contribute to testicular cooling. Despite a long-standing paradigm that mammalian testes are close to hypoxia and blood flow does not increase in response to testicular heating, in recent studies in mice, rams and bulls, warming the testes stimulated increased blood flow, with no indications of testicular hypoxia. Furthermore, hypoxia did not replicate the changes and hyperoxia did not provide protection. Therefore, we concluded that testicular hyperthermia and not secondary hypoxia affects spermatogenesis and sperm quality. Increasing testicular temperature causes many cellular and subcellular changes. As testicular temperature increases, the proportion of defective sperm increases; recovery is dependent upon the nature and duration of the thermal insult. Environmental control of temperature (shade, sprinklers, air conditioning) and some chemical approaches (e.g., melatonin and L-arginine) have promise in reducing the effects of heat stress on bull reproduction.

Os testículos dos bovinos devem permanecer 2 a 6 ºC abaixo da temperatura corporal para produzirem espermatozoides morfologicamente normais, móveis e férteis. A termorregulação escrotal/testicular é complexa e envolve a enovelada artéria testicular circundada pelo plexo venoso pampiniforme, que constituem o cone vascular, um sistema contracorrente de troca de calor. Adicionalmente, a perda de calor por radiação pelo escroto, sudorese, suprimento sanguíneo arterial complementar, e os gradientes de temperatura no escroto e testículos contribuem para o resfriamento testicular. A despeito do duradouro paradigma de que os testículos estão em uma situação de quase hipóxia e que o fluxo sanguíneo não aumenta em resposta ao aquecimento testicular, em recentes estudos em camundongos, carneiros e touros, o aquecimento testicular estimulou o fluxo sanguíneo sem serem observados sinais de hipóxia. Além disso, a hipóxia não afetou os testículos e a hiperóxia não conferiu proteção. Portanto, concluímos que é a hipertermia testicular, e não a hipóxia secundária, que afeta a espermatogênese e a qualidade seminal. O aumento da temperatura testicular causa muitas mudanças celulares e subcelulares. À medida que a temperatura aumenta, a proporção de espermatozoides defeituosos aumenta. A recuperação depende da natureza e duração do insulto térmico. O controle ambiental (sombra, aspersores de água e ar condicionado) e algumas abordagens químicas (ex., melatonina e L-arginina) são medidas promissoras de redução dos efeitos do estresse térmico na reprodução de touros

Crude glycerin inclusion in Santa Inês ewes' diet before and during the breeding season: its effects on physiological parameters, hematological variables, and reproductive performance / Inclusão de glicerina bruta na dieta de ovelhas Santa Inês antes e durante a estação de monta: Seus efeitos nos parâmetros fisiológicos, variáveis hematológicas e desempenho reprodutivo

In this study, we aimed to evaluate the effect of concentrate supplementation containing crude glycerin (CG) before and during the breeding season on the physiological and blood biochemical variables as well as on the reproductive performance of Santa Inês ewes. A total of 24 ewes (12 pluriparous and 12 nulliparous ewes, 4 and 1.5 years old, weighing an average of 40 ± 5 and 27 ± 3 kg, respectively) were randomly assigned to three treatments consisting of different dietary concentrations of CG (0%, 5%, and 10 % of the total dry matter). The experiment lasted 63 days and was divided into three 21-day phases. In the first and second phases, the animals were subjected to flushing. In the second and third phases, we evaluated the animals' reproductive performance. Weather, physiological, and blood biochemical variables were also studied. The results indicated that the inclusion of CG did not influence significantly (P > 0.05) either the ewes' body weight or their body condition score. All ewes exhibited estrus during the breeding season. Their respiratory rate was significantly influenced by the time of day (P < 0.0001). A 10% CG supplementation did not drastically change the hematological and biochemical variables, which were within the reference ranges. However, the week of supplementation influenced sérum metabolites (P < 0.05). Thus, these results indicate that CG could be used in up to 10% in replacement of ground corn without significantly affecting the physiological, hematological, and biochemical parameters of the ewes or their reproductive performance before and during the breeding season.(AU)

Neste estudo, objetivamos avaliar o efeito da suplementação concentrada contendo glicerina bruta (GB) antes e durante a estação de monta sobre as variáveis bioquímicas e fisiológicas, bem como sobre o desempenho reprodutivo das ovelhas Santa Inês. Um total de 24 ovelhas (12 pluríparas e 12 nulíparas, de 4 e 1,5 anos de idade, pesando em média 40 ± 5 e 27 ± 3 kg, respectivamente) foram distribuídas aleatoriamente em três tratamentos constituídos por diferentes concentrações dietéticas de GB (0, 5 e 10% da matéria seca total). O experimento durou 63 dias e foi dividido em três fases de 21 dias. Na primeira e segunda fase, os animais foram submetidos ao flushing alimentar. Na segunda e terceira fase, avaliamos o desempenho reprodutivo dos animais. Variáveis climáticas, fisiológicas e bioquímicas sanguíneas também foram estudadas. Os resultados indicaram que a inclusão de GB não influenciou significativamente (P > 0,05) no peso corporal das ovelhas nem em seu escore de condição corporal. Todas as ovelhas exibiram estro durante a estação reprodutiva. A frequência respiratória foi significativamente influenciada pela hora do dia (P < 0,0001). Uma suplementação com 10% de GB não alterou drasticamente as variáveis hematológicas e bioquímicas, que estavam dentro do intervalo de referência. No entanto, a semana de suplementação influenciou os metabólitos séricos (P < 0,05). Sendo assim, esses resultados indicam que a GB pode ser utilizada em até 10% na substituição do milho moído, sem afetar significativamente os parâmetros fisiológicos, hematológicos e bioquímicos das ovelhas assim como o desempenho reprodutivo antes e durante a estação de monta.(AU)

Efeito da suplementação com óleo de avocado (Persea americana Mill) na temperatura superficial corpórea de equinos antes e após exercício em esteira / [Effect of supplementation with avocado oil (Persea americana Mill) on body surface temperature of horses before and after exercise on treadmill]

Oito equinos foram distribuídos em delineamento randomizado cruzado, sendo um grupo sem suplementação (GC) e outro grupo suplementado com óleo de avocado (GOAv) por um período de sete semanas. Ao fim da sexta semana, os animais foram submetidos a teste padrão de exercício progressivo (TPEP) e, após sete dias, a teste de baixa intensidade e longa duração (BILD). Após o primeiro ciclo, houve período de descanso "washout" de 30 dias para troca de grupos para o segundo ciclo, que seguiu o protocolo do primeiro. A termorregulação foi avaliada com base na temperatura retal e na temperatura superficial corpórea, obtidas por termografia, de 15 regiões de interesse. A temperatura retal e as imagens termográficas foram obtidas antes, um minuto e 15 minutos após o exercício. Não houve diferença entre os grupos GC e GOAv em nenhum momento. Os resultados obtidos neste estudo revelaram que a suplementação de 5% da matéria seca (MS) com óleo de avocado por seis e sete semanas não influenciou na termorregulação com base na temperatura superficial corpórea dos equinos submetidos ao teste padrão de exercício progressivo (TPEP) e ao exercício de baixa intensidade e longa duração (BILD), respectivamente.(AU)

Eight equines were distributed in a randomized crossover design, one control group (CG) without supplementation and another group supplemented (SG) with avocado oil for a period of six weeks. At the end of the sixth week, the animals were submitted to standard exercise test (SET) and after seven days to the low intensity test (LIT). After the first cycle, there was a 30-day washout rest period to exchange groups for the second cycle, which followed the protocol of the first one. Thermoregulation was evaluated based on rectal temperature and body surface temperature of 15 regions of interest obtained by thermography. Rectal temperature and thermographic images were obtained before, one minute and 15 minutes after exercise. There was no difference between the CG and SG at any time. The results obtained in this study revealed that the supplementation of 5% of dry matter with avocado oil for six and seven weeks did not influence the thermoregulation based on the body surface temperature of the horses submitted to SET and LIT, respectively.(AU)

Scrotal thermography to assess the seminal quality in Nelore and Girolando bulls / Termografia escrotal e a relação com a qualidade seminal em touros Nelore e Girolando

Bull selection by andrological examination aims to estimate the reproductive capacity of the male. Bulls of zebu origin adapt better to high temperatures than bulls of taurine origin, which may influence scrotum temperature and seminal quality due to the imbalance of testicular thermoregulation. The objective of this study was to investigate the relationship between bioclimatic variables, the temperature of body and scrotal areas, assessed with infrared thermography, and the quality of fresh and post-thawed semen in zebu Nelore bulls (Bos taurus indicus) and Girolando bulls (Bos taurus taurus x Bos taurus indicus). Bulls were kept in pickets with access to water, mineral mix and a diet supplemented with concentrate. Infrared thermographs of the scrotum, orbital globe and muzzle were performed twice a week with a Flir E40 thermal imager. For scrotal thermograms, we analyzed the temperatures of the spermatic cord, proximal and distal portion of the testes and tail of the epididymis using the Flir Tools software. Samples were collected using an artificial vagina and the ejaculates were processed and frozen in liquid nitrogen until further analyses. Data were analyzed with the Tukey test or the Kruskall-Wallis test, depending on their normal distribution. Our results showed differences (p < 0.05) between the two breeds regarding the temperature in the ocular globe, spermatic cord and proximal portion of the scrotum. Nelore bulls presented lower temperature in the body and in certain regions of the scrotum compared to Girolando bulls. Seminal characteristics varied between breeds, with the Nelore breed presenting better semen. Positive correlations were observed between minor sperm defects and ventral regions of the testes and tails of the epididymis in Girolando bulls. Nelore bulls were less influenced by climatic variables and presented lower temperature in skin surface areas in the...

A seleção de touros pelo exame andrológico visa estimar a capacidade reprodutiva do macho. Touros de origem zebuína apresentam melhor adaptabilidade às altas temperaturas, em relação aos touros de origem taurina, podendo influenciar na temperatura do escroto e na qualidade seminal pelo desequilíbrio da termorregulação testicular. Objetivou-se avaliar a influência das variáveis bioclimáticas e a relação de perfis de termogramas por infravermelho de áreas do corpo e escroto com a qualidade do sêmen fresco e descongelado em touros das raças Nelore e Girolando, mantidos em Central de Inseminação Artificial. Foram utilizados quatro touros Nelore e quatro Girolando, mantidos em piquetes com acesso a água e mistura mineral; e suplementação com concentrado. Termografias infravermelhas do escroto, globo ocular e mufla foram realizadas duas vezes por semana com termovisor Flir E40. Para os termogramas escrotais, as temperaturas do cordão espermático, porção proximal e distal dos testículos e cauda do epidídimo foram analisadas utilizando o software Flir Tools. Foram realizadas colheitas de sêmen com vagina artificial e os ejaculados processados e congelados em nitrogênio líquido e analisados na pós-descongelação. Os dados passaram pelo teste de normalidade e teste Tukey; e na ausência de normalidade pelo teste Kruskall- Wallis. Entre raças, foram observadas diferenças (P < 0,05) nas temperaturas do globo ocular, cordão espermático e porção proximal do escroto. Os touros Nelore apresentaram menor temperatura corpórea e de regiões do escroto, em relação aos touros Girolando. As características seminais variaram entre raças (P < 0,05), a raça Nelore apresentou sêmen de melhor qualidade. Correlações positivas (P < 0,05) foram observadas entre defeitos espermáticos menores e temperaturas da região ventral dos testículos e das caudas dos epidídimos. em touros Girolando. Os touros da raça...