Hypothalamic Neuromodulation and Control of the Dermal Surface Temperature of Livestock during Hyperthermia.

Hyperthermia elicits several physiological and behavioral responses in livestock to restore thermal neutrality. Among these responses, vasodilation and sweating help to reduce core body temperature by increasing heat dissipation by radiation and evaporation. Thermoregulatory behaviors such as increasing standing time, reducing feed intake, shade-seeking, and limiting locomotor activity also increase heat loss. These mechanisms are elicited by the connection between peripheral thermoreceptors and cerebral centers, such as the preoptic area of the hypothalamus. Considering the importance of this thermoregulatory pathway, this review aims to discuss the hypothalamic control of hyperthermia in livestock, including the main physiological and behavioral changes that animals adopt to maintain their thermal stability.

Use of Infrared Thermography and Heart Rate Variability to Evaluate Autonomic Activity in Domestic Animals.

Most of the responses present in animals when exposed to stressors are mediated by the autonomic nervous system. The sympathetic nervous system, known as the one responsible for the "fight or flight" reaction, triggers cardiovascular changes such as tachycardia or vasomotor alterations to restore homeostasis. Increase in body temperature in stressed animals also activates peripheral compensatory mechanisms such as cutaneous vasodilation to increase heat exchange. Since changes in skin blood flow influence the amount of heat dissipation, infrared thermography is suggested as a tool that can detect said changes. The present review aims to analyze the application of infrared thermography as a method to assess stress-related autonomic activity, and their association with the cardiovascular and heart rate variability in domestic animals.

Utilization of Infrared Thermography in Assessing Thermal Responses of Farm Animals under Heat Stress.

Heat stress is a condition that can affect the health, performance, and welfare of farm animals. The perception of thermal stress leads to the activation of the autonomic nervous system to start a series of physiological and behavioral mechanisms to restore thermostability. One of these mechanisms is vasodilation of peripheral blood vessels to increase heat loss through the skin. Due to this aspect, infrared thermography has been suggested as a method to assess the thermal state of animals and predict rectal temperature values noninvasively. However, it is important to consider that predicting rectal temperature is challenging, and its association with IRT is not always a direct linear relationship. The present review aims to analyze the neurobiological response associated with heat stress and how thermal imaging in different thermal windows can be used to recognize heat stress in farmed ungulates.

Hypothalamic Neuromodulation of Hypothermia in Domestic Animals.

When an organism detects decreases in their core body temperature, the hypothalamus, the main thermoregulatory center, triggers compensatory responses. These responses include vasomotor changes to prevent heat loss and physiological mechanisms (e.g., shivering and non-shivering thermogenesis) for heat production. Both types of changes require the participation of peripheral thermoreceptors, afferent signaling to the spinal cord and hypothalamus, and efferent pathways to motor and/or sympathetic neurons. The present review aims to analyze the scientific evidence of the hypothalamic control of hypothermia and the central and peripheral changes that are triggered in domestic animals.

Effect of heat stress on TNF-α, TNFRI and TNFRII expression in BLV infected dairy cattle.

High temperatures for extended periods, which do not allow animals to recover from heat stress, affect in particular those BLV-infected animals that carry a high proviral load. For this study, animals were discriminated between BLV (+) and BLV (-), and those belonging to the first group, were classified based on their proviral load. The expression of the inflammatory cytokine TNF-α and its receptors, which play an important role in disease progression, were quantified by qPCR in two different seasons. During the summer, average temperature was 19.8 °C, maximums higher than 30 °C were frequent. Instead, during the autumn, the average temperature was 12.63 °C, and temperatures never exceeded 27 °C. During this season, almost no periods of temperatures exceeded the comfort limit. Our results revealed that the expression levels of TNF-α and its receptors were downregulated in animals with high proviral load. This fact could affect their antiviral response and predispose to viral dissemination; over time, animals with a poorer immune system are prone to acquiring opportunistic diseases. Conversely, animals with LPL maintained their expression profile, with behavior comparable to non-infected animals. These findings should be considered by producers and researchers, given the problems that global warming is causing lately to the planet.

Hepatic hematopoiesis in the alpaca (Vicugna pacos), a species with development in hypoxic environments.

Hematopoiesis occurs in different anatomical niches throughout the life of the individual. The first hematopoietic extra-embryonic stage is replaced by a intra-embryonic stage that occurs in a region that is adjacent to the dorsal aorta. Then, the prenatal hematopoietic function is continued by the liver and spleen, and later by the bone marrow. The objective of the present work was to describe the morphological characteristics of hepatic hematopoiesis in the alpaca and to analyze the proportion of the hematopoietic compartment of the organ and the cell types, at different times of ontogeny. Sixty-two alpaca samples were collected from the municipal slaughterhouse of Huancavelica, Perú. They were processed by routine histological techniques. Hematoxylin-eosin staining, special dyes, immunohistochemical techniques and supplementary analyses by lectinhistochemistry, were performed. The prenatal liver is an important structure in the expansion and differentiation of hematopoietic stem cells. Their hematopoietic activity was characterized by four stages: initiation, expansion, peak, and involution. The liver started its hematopoietic function at 21 days EGA and it was maintained until shortly before birth. Differences were found in the proportion and morphology of the hematopoietic tissue in the different groups corresponding to each gestational stage.

Neurophysiology of Milk Ejection and Prestimulation in Dairy Buffaloes.

The present review aims to integrate the anatomical characteristics of the mammary gland and the neurophysiology of milk ejection to understand the milking capacity of the water buffalo. Since one of the main uses of this species is milk production, this article will analyze the controversies on the use of oxytocin as a stimulant during milking as well as the existing alternatives that farmers apply to promote correct stimulation during milk letdown. According to the available literature, the efficiency of the milking process, the quality of the milk, and the health of the animals are elements that require the consideration of species-specific characteristics to enhance the performance of buffaloes. The incorporation of technological innovations and competitive strategies could contribute to a better understanding of water buffalo in the milk industry.

Alterations in TNF-α and its receptors expression in cows undergoing heat stress.

Heat stress is one of the environmental factors that most severely affects milk industry, as it has impact on production, immune responses and reproductive performance. The present study was conducted with high-performance Holando-Argentino cows. Our objective was to study TNF-α and its receptors pattern expression in cows from a region characterized by extreme climatic seasonality. Animals were evaluated in three periods: spring (n = 15), summer (n = 14) and autumn (n = 11). Meteorological records from a local station were used to estimate the temperature and humidity index (THI) by means of an equation previously defined. A THI higher than 68 is indicative of stressing conditions. During the summer period, the animals were exposed to 8.5 ±â€¯1.09 h of heat stress, or THI > 68. In spring, stress hours were reduced to 1.4 ±â€¯0.5 every day, while during the autumn, there were no recorded heat stress events. Expression of TNF-α, and its receptors was determined by qPCR. During the summer, TNF-α and its receptors expression diminished drastically compared to the rest of the year, when stressful conditions were infrequent. We conclude that animals that are not physiologically prepared to resist high temperatures might have a less efficient immune response, reinforcing the need to develop new strategies to improve animal welfare.

Pain at the Slaughterhouse in Ruminants with a Focus on the Neurobiology of Sensitisation.

We pose, based on a neurobiological examination, that events that occur around the time of slaughter have the potential to intensify the pain response, through the processes of sensitisation and enhanced transmission. Sensitisation, or an enhanced response to painful stimuli, is a well-discussed phenomenon in the human medical literature, which can arise from previous injury to an area, inflammatory reactions, or previous overstimulation of the stress axes. A number of events that occur prior to arrival at, or in the slaughterhouse, may lead to presence of these factors. This includes previous on-farm pathology, injuries arising from transport and handling and lack of habituation to humans. Whilst there is limited evidence of a direct effect of these on the processes of sensitisation in animals at slaughter, by analogy with the human neurobiology literature the connection seems plausible. In this review a neurobiological approach is taken to discuss this hypothesis in the light of basic science, and extrapolations from existing literature on the slaughter of ruminants. To confirm the postulated link between events at slaughter, and processes of hypersensitisation, further dedicated study is required.

Topography and morphology of the llama (Lama glama) stomach

El estómago de los camelidos sudamericanos presenta una estructura morfológica diferente al de rumiantes verdaderos. El objetivo del presente trabajo fue describir las caracteristicas anatómicas e histológicas del estómago de la llama y sus relaciones con las estructuras adyacentes. Se utilizaron cuatro llamas machos. Las muestras para estudios anatómicos fueron fijadas por perfusión con formol al 10 por ciento. Para histologia, las muestras fueron fijadas en Bouin y procesadas rutinariamente. Los estudios anatómicos mostraron que el compartimiento proximal esta localizado totalmente en la pared abdominal izquierda. Un labio derecho simple, el pliegue ventricular, resulta notorio. El compartimiento intermedio presenta forma arri¤onada con paredes gruesas. El compartimiento distal es elongado y tubular hacia la zona ventral derecha de la cavidad abdominal. Histológicamente, los compartimientos proximal e intermedio presentan areas con y sin glandulas. La región no glandular esta cubierta por epitelio plano estratificado con pliegues y sin papilas. El area glandular presenta pliegues cuyos recesos originan profundos sacos, ocupados por glandulas tubulares simples, tapizadas por epitelio cilindrico simple. El compartimiento distal es completamente glandular.

Morfología del hígado de llama, lama glama / Morphology of the liver of the llama, lama glama

Se observó la estructura macro y microscópica del hígado de 6 llamas adultas (Lama glama), 4 machos y 2 hembras. El hígado se ubica en la región abdominal craneal, a la derecha del plano mediano. Carece de vesícula biliar y el conducto hepático se une al conducto pancreático mayor, a unos 3 cm del duodeno, formando el conducto hepato-pancreático, el cual desemboca mediante el trayecto intramural en la segunda curva de la ese sigmoídea del duodeno. En los lobulillos hepáticos, el tejido conectivo de soporte es escaso, se halla limitado al espacio porta. Los estudios morfológicos brindan un soporte estructural para la realización de técnicas de diagnóstico específicas de este órgano, como por ejemplo, la biopsia hepática

Inmunohistoquímica de la red linfoide del bovino: leucocitos mononucleares y su distribución orgánica / Immunohistochemistry of bovine lymphoid system: mononuclear leukocytes and organic distribution

Una caracterización celular sistemática mediante pruebas inmunohistoquímicas, fue desarrollada en la red linfoide bovina. Se analizaron suspensiones de células mononucleares obtenidas por perfusión de órganos participantes de la respuesta inmune del bovino. Las técnicas utilizadas fueron rosetado, inmunofluorescencia e inmunoperoxidasa amplificada por el complejo avidina-biotina para la detección de receptores de membrana, inmunoglobulinas de superficie y cadenas livianas de inmunoglubulinas intracitoplasmáticas. Los resultados obtenidos permitieron distinguir diferencias porcentuales relativas en las poblaciones celulares de los órganos analizados, comprobando que la distribución leucocitaria es irregular, presumiblemente por características de función y/o estimulación antigénica. No se encuentran en la bibliografía, datos previos sobre distribución de las distintas subpoblaciones celulares en órganos linfoides bovinos, constituyendo el presente trabajo un aporte para el estudio del sistema y la comprensión de su funcionalidad