ABSTRACT Stress-induced hyperthermia is an acute response that occurs in the short term in individuals who are facing a stressful stimulus, considering that this response can provide significant information on stress degree. However, it is not yet clear whether the neurological pathway can be modified to the degree to which stress is perceived. Furthermore, there is not enough information as to how factors that modify perception stress degree act on stress-induced Hyperthermia. Besides, research indicates that the thermal response possibly has a greater cardiovascular influence by generating energy resource consumption. In the same way, the factors that induce this response have been questioned, since recent evidence indicates that social factors such as the presence of conspecifics attenuate the thermal response, but, when coexistence or some other action like parenting is prevented, the response is to the reverse. For this reason, the objective of this article was to analyze the neurobiology of stress-induced hyperthermia and its conceptual difference with infectious fever, as well as to integrate the factors that modulate it, analyzing recent scientific advances in stress-induced thermal response.

RESUMEN: La hipertermia inducida por estrés es una respuesta aguda que se presenta a corto plazo en individuos que están frente a un estímulo estresante y que dicha respuesta puede aportar información significativa sobre el grado de estrés. Sin embargo, no es claro todavía si la vía neurológica pueda ser modificada al mismo grado en la que se percibe el estrés. Además, no se tiene suficiente claridad en cómo es que los factores que modifican el grado de percepción de estrés actúan sobre la Hipertermia Inducida por Estrés (SIH, por sus siglas en inglés). Asimismo, las investigaciones señalan que posiblemente la respuesta térmica tenga una mayor influencia cardiovascular al generar el consumo de recursos energéticos. De igual manera, los factores físicos que inducen dicha respuesta han sido cuestionados, ya que la evidencia reciente señala que además los factores sociales como la presencia de coespecíficos atenúan la respuesta térmica pero cuando se impide la convivencia o alguna otra conducta social como la crianza, la respuesta incrementa la SIH. Por tal motivo, el objetivo de este artículo es analizar la neurobiología de la hipertermia inducida por estrés y su diferencia conceptual con la fiebre infecciosa, así como integrar los factores que lo modulan, analizando los avances científicos recientes de la respuesta térmica inducida por estrés.

Resumo Foi avaliado o efeito do estresse produzido pelo tempo de espera pré-abate sobre a produção de aminas biogênicas, pH e cor pelo sistema CIELab (onde três variáveis L*, a*, b* foram determinadas: L* indica a luminosidade, a* indica o vermelho e b* determina o amarelo) na carne de peito de frango. Antes do abate 25 frangos de carne foram selecionados e divididos em cinco grupos conforme o tempo de espera pré-abate (30 min ou 3 h), programação dia/noite (diurno ou noturno) e controle (sem tempo de espera). Após abate, os peitos (M. Pectoralis major) foram separados, estocados por 9 dias a 4°C, e analisados cada 3 dias. Os resultados evidenciaram uma redução do pH nas aves que aguardaram o abate na noite. Além disso durante a estocagem incrementou-se os valores de aminas biogênicas e da luminosidade (L*) e houve redução dos teores de vermelhos (a*) no tempo de espera de três horas (diurno ou noturno). As concentrações da cadaverina incrementaram-se a partir do dia 6 de estocagem. O tempo e horário de espera em frangos de carne pode é um fator de estresse pré-abate que afeta a qualidade da carne. Contudo, é recomendável realizar o abate dos frangos imediatamente após de sua chegada ao centro de abate.

Abstract The effect of pre-slaughter lairage stress on biogenic amines, pH, and color with the CIELab system (where three variables L*, a*, b* are estimated: L* for lightness, a* defines redness, and b* defines yellowness) in chicken breast meat was investigated. Before slaughtering, 25 broilers were selected and divided into five groups according to lairage holding time (30 min or 3 h), day/night schedule (daylight or nighttime) and control (no lairage). After slaughtering, breasts (M. Pectoralis major) were removed, stored for 9 days at 4 °C, and analyzed every 3 days. The results showed a pH decrease during nighttime holding. Also, a three-hour pre-slaughter holding (daytime or night) resulted in high biogenic amine concentration, increase in lightness (L*), and reduction in redness (a*) during storage. Cadaverine concentration showed a rapid increase from day 6 onward. The time and schedule of chicken lairage is a pre-slaughter stress factor that affects meat quality. Based on these observations, it is recommended to slaughter chickens immediately on arrival at the processing plants.

The consumption of some long chain polyunsaturated fatty acids (LCPUFA), in particular docosahexanoic (DHA), eicosapentanoic (EPA) and conjugated linoleic (CLA) acids is beneficial for human health, thus its incorporation to meat gives added value, but sensory characteristics could be altered, causing rejection by the consumer. The objective of the present study was to evaluate the effect of adding these three LCPUFA to pig diet on physiochemical and sensory meat quality. The experimental design was randomized blocks with the following treatments: T1) diet+CLA; T2) diet+DHA+EPA; T3) diet+DHA+EPA+CLA; T4) diet (control). The data were analyzed using ANOVA and principal component analysis (PCA). Means were compared with Tukey test (p≤0.05). Thirty-two Pietrain x Landrace x York x Duroc castrated pigs were used in two fattening phases: 4 weeks of development and 4 weeks of finishing. They were then electroanesthetized and sacrificed. To carry out the physiochemical analyses (pH, water activity, hardness and cooking loss) and qualitative description (flavor, texture and aroma) samples were taken from the Longissimus dorsi muscle. Flavor and aroma of pork meat fed with LCPUFA was described as roasted, beef-like, and sheep-like, with soft and juicy texture, although less acceptable than the control. Roasted flavor, a desirable attribute in meats, decreased in samples obtained from pigs with diets including DHA and EPA, and fishy aroma and flavor were not detected.

El consumo de algunos ácidos grasos poliinsaturados de cadena larga (AGPCL), en particular los ácidos docosahexanoico (ADH), eicosapentanoico (AEP) y linoleico conjugado (ALC), es benéfico para la salud humana, por lo cual su incorporación a la carne de abasto le da un valor agregado, pero las características sensoriales podrían alterarse ocasionando el rechazo del consumidor. El objetivo del presente estudio fue evaluar el efecto de adicionar estos tres AGPCL a la dieta de cerdos en variables de calidad fisicoquímica y sensorial de la carne. El diseño experimental fue de bloques al azar y los tratamientos fueron: T1) dieta+ALC; T2) dieta+ADH+AEP; T3) dieta+ADH+AEP+ALC; T4) dieta (testigo). Los datos se analizaron mediante ANDEVA y componentes principales (ACP); las medias se compararon con la prueba de Tukey (p≤0.05). Se usaron 32 cerdos castrados, Pietrain x Landrace x York x Duroc, en engorda de dos fases: 4 semanas de desarrollo y 4 semanas de finalización, después se electroinsensibilizaron y sacrificaron. Para realizar los análisis fisicoquímicos (pH, actividad de agua, dureza y pérdidas por cocción) y descriptivo cualitativo (sabor, textura y aroma) se tomaron muestras del músculo Longissimus dorsi. El sabor y aroma de la carne de los cerdos alimentados con AGPCL se describió como rostizado, a res, y a borrego, con textura suave y jugosa, aunque menos aceptable que el testigo. El sabor a rostizado, un atributo deseable en las carnes, disminuyó en las muestras obtenidas de cerdos que recibieron dietas con ADH y AEP, y no se detectó aroma ni sabor a pescado.

Nowadays, modern swine production techniques promote early weaning. Weaning constitutes one of the most critical stages in the productive life of swine as it is a phase that entails a whole series of stressful factors and physiological changes. This review examines the most important factors that cause stress during this stage, including: separation from the sow, transport, changes in alimentation, lodging in different installations, and being grouped together with strange piglets. The interaction of young pigs with all these stressor factors exercises a cumulative effect that intensifies the level of stress they experience during separation from the sow during the weaning process itself, an event that frequently results in "delayed growth" accompanied by an increased susceptibility to disease-causing, enteric pathogenic agents. For these reasons, it is important to adequately control the variety of factors that affect the physiology, metabolism and behavior of piglets. The conclusion is that both knowledge of the biology of the species and suitable personnel training are necessary to reduce the problems that arise from these issues related to the welfare of weaned piglets. Finally, this study recommends some practices derived from the findings presented, with a view to improving the welfare of recently weaned piglets.

Hoy en día, las modernas técnicas de producción porcina exigen cada vez más destetes tempranos. Sin embrago, el destete representa una de las etapas más críticas en la vida productiva del cerdo, debido a que durante ella se suman una serie de factores estresantes y cambios fisiológicos. En la presente revisión se analizan los factores más importantes que causan estrés durante esta etapa, como la separación de la cerda, el transporte, el cambio de alimento, el alojamiento en nuevas instalaciones y el agrupamiento con lechones extraños. La interacción de los lechones con estos factores estresantes incrementa el nivel de estrés que representa, per se, la separación de la cerda y el lechón durante el destete, ya que habitualmente originan "retraso en el crecimiento", además de aumento de la susceptibilidad frente a agentes patógenos entéricos causantes de enfermedades. Por ello, los distintos factores que afectan la fisiología, el metabolismo y el comportamiento del lechón deben ser controlados adecuadamente. Se concluye que el conocimiento de la biología de la especie y un entrenamiento adecuado del personal, son necesarios para disminuir los problemas de bienestar del lechón destetado, por lo que, con el fin de evitarlos, se recomiendan algunas prácticas derivadas de los hallazgos presentados.

The aim of the study was to monitor the sow maternal response to a low oxitocin dose in an advanced parturition stage in eutocic and maternal-foetal dystocia. Sixty York x Landrace sows, 30 with eutocic farrowing and 30 with maternal-foetal dystocia were assigned into two different groups: 15 received 0.083 IU/kg of oxytocin after the expulsion of the fifth piglet, and 15 received no treatment at all. Blood samples from every sow in trial were taken from the ear vein at three different times: immediately after membrane rupture, after the fifth piglet was born, and at the end of the farrowing. A third generation blood gas analyzer was used. Results show that when parturition was resumed, sows with maternal-foetal dystocia had significantly greater lactate, pCO2 and ear temperature (P < 0.001), compared with the eutocic sow group. Results from physiological variables and neonatal traits monitored in this experiment show evidence that oxytocin should not be used in normal parturition without stillbirths, since oxytocin in this case had adverse effects on sow performance. Oxytocin administered at the beginning of the second half of parturition decreased 50% the number of born alive with asphyxia in eutocic and dystocic sows, and on the other hand, decreased 50% the number of intra-partum stillbirths in the dystocic group. This is the first study describing the critical blood variables in dystocic sows (pH, pCO2, pO2, glucose, lactate and HCO3), using a third generation gasometry device.

Con el propósito de evaluar las respuestas maternas a dosis baja de oxitocina en estado avanzado del parto en cerdas con eutocia y distocia materno-fetal, se seleccionaron 60 cerdas de la cruza Yorkshire x Landrace, 30 eutócicas y 30 con distocia materno-fetal. Las cerdas de cada grupo fueron divididas en subgrupos: 15 recibieron 0.083 UI/kg de oxitocina después de la expulsión del quinto lechón, las otras 15 no fueron tratadas. Se obtuvieron muestras sanguíneas en cada una de las cerdas mediante punción de vena auricular después de la rotura de la fuente, al quinto lechón y al finalizar el parto; las muestras fueron evaluadas con un analizador de gases sanguíneos. Al finalizar el parto, las cerdas que presentaron partos con distocia materno-fetal incrementaron significativamente (P < 0.001) los niveles de lactato, pCO2 y temperatura, respecto de las hembras que presentaron partos eutócicos. Los resultados de las variables fisiológicas y los indicadores neonatales evaluados en este experimento son evidencia de que la oxitocina no debe aplicarse en partos con evolución normal sin nacidos muertos, ya que posee efectos adversos sobre el desempeño de la cerda. La oxitocina en cerdas, administrada al inicio de la segunda mitad del parto, disminuyó en 50% los nacidos con asfixia en cerdas eutócicas y distócicas; asimismo, redujo en 50% el número de muertes intraparto en las hembras distócicas. Los resultados del presente experimento determinan por primera vez la evolución de los parámetros críticos sanguíneos de la cerda con partos distócicos (pH, pCO2, pO2, glucosa, lactato y HCO3) utilizando equipo de gasometría de tercera generación.

Current globalization policies demand animal welfare standards on animal transportation. In spite of international tendencies to commercialize meat cuts while decreasing live animal transit, transport is still one of the major problems in terms of animal welfare, besides carcass and meat by-products' quality. The present review analyzes, in general terms, the different definitions on animal welfare and factors affecting pig welfare in transit. Several case studies are referred to as examples, showing the animal response to stress during transport and its effects on both meat quality and the economic impact. In addition, legal requirements and Mexican regulations for pig transportation are also described. Information in regard to swine stress and welfare in transit, considers a number of factors that alter the animal metabolic homeostasis with subsequent negative effects on pork quality. It is conclude that knowledge on basic animal behavioral and physiological needs during transport, as well as a suitable training of personnel, are necessary for reducing animal welfare problems. Last but not least, some recommendations on handling practices are given in order to improve swine welfare during transit.

En el marco actual de la globalización, hablar de transporte animal conlleva realizar prácticas que mejoren el bienestar animal, aunque existe la tendencia mundial de incrementar el mercado de la carne en cortes, así como disminuir el comercio de animales vivos, el transporte constituye uno de los factores más preocupantes en términos del bienestar animal, además del impacto en la calidad de la canal y los subproductos respectivos. En la presente revisión se analizan, en términos generales, las distintas definiciones de bienestar animal, así como los factores más importantes que alteran el bienestar de los cerdos durante el transporte; se describen los requisitos legales y la normatividad mexicana para el transporte de animales, así como varios estudios de la respuesta fisiológica del animal durante condiciones adversas del transporte, se señalan, además, las repercusiones sobre la calidad de la carne y su impacto económico. La información con respecto al estrés de los cerdos y su bienestar durante el transporte, considera numerosos factores que alteran el equilibrio homeostático animal y que propician efectos negativos sobre calidad de la carne. Se concluye que tanto el conocimiento de la biología de la especie, como un entrenamiento del personal, son necesarios para disminuir los problemas de bienestar. Finalmente, se recomiendan algunas prácticas derivadas de los hallazgos presentados, con el fin de que se mejore el bienestar de los cerdos en tránsito.

Oxytocin is extensively used to induce or augment uterine contractions, especially to facilitate the third stage of labor in humans. Administration of oxytocin to parturient sows reduces duration of labor whereas mortality of the offspring may remain unchanged. This study aimed to evaluate whether time of administration of oxytocin during parturition may alter the uterine response and fetal outcomes. Two hundred parturient sows were randomly assigned to intramuscularly receive either saline solution (control group) or oxytocin 0.083 IU/kg immediately after the delivery of the 1st, 4th or 8th piglet (groups O-1, 0-4 and 0-8, respectively). Uterine effects and fetal outcomes were registered in all groups. The duration of labor was 20-40 min shorter (P < 0.0001) and time interval between babies was reduced by 3-5 min (P < 0.0001) in the three groups receiving oxytocin. The duration and intensity of contractions, meconium-stained piglets and intrapartum deaths decreased as time at which oxytocin administered during labor was increased. In group 0-8, we observed approximately 70% less meconium-stained piglets and intrapartum deaths than in the control group. In conclusion, oxytocin administered at early phases of parturition to sows may increase duration and intensity of uterine contractions as well as adverse fetal outcomes