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Heat stress has been recognized as a serious problem in dairy farms around the world due to the increasing heat waves and higher genetic potential of dairy cows. In Chile, milk production is concentrated in the southern regions of the country, where animals graze all year around, consequently being exposed directly to environmental conditions. Nevertheless, there are few studies conducted in Chile that have evaluated at the commercial level the impact of heat stress on milk production. The aim of this study was to assess the effects of summer conditions, across periods, on the milk production of cows at different stages of lactation in a dairy farm located in Southern Chile. Daily meteorological and milk yield records of three summers from a dairy farm were collected to characterize the relationship between two thermal stress indices and milk yield. The thermal comfort indices used were the comprehensive climate index (CCI), and the adjusted temperature humidity index (THIadj). The average values of CCI and THIadj were dependent on the period (P < 0.0001) with maximum CCI of 40.2 °C, 31.7 °C, and 27.5 °C for the 2012-2013, 2015-2016, and 2016-2017 periods, respectively. A similar response was recorded when THIadj was used (85.5, 78.0, and 73.9, respectively). In the 2012-2013 summer, 44.4% of the days presented conditions of heat stress (CCI ≥23), a value that fell to 26.7% in the summer of 2015-2016 and only 5.6% in the 2016-2017. On the opposite, when the THIadj was used, these values were 50%, 48.9%, and 5.6%, respectively. In conclusion, both comfort thermal indices are good tools to determine the risk of thermal stress in dairy cows, with a large variation between the three summer periods but also between indices. Likewise, cows in the early and mid-lactation periods are more affected in terms of milk yield.

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Animal welfare and productive performance are compromised when animals are housed in environments which place them outside their thermal comfort zone. However, the identification of thermal stress, when based on air properties, suggests the use of outdated and generic indices. The objective of this work was to develop and validate a methodology for classifying and diagnosing heat stress in production animals based on psychrometric air relations. The model was created for broilers, pigs, dairy cattle, and laying birds, categorized into a total of 21 breeding phases. For each phase, a bibliographic search was carried out for the psychrometric parameters of the air-dry bulb temperature (AT) and relative humidity (RH)-that satisfied the animals' critical and ideal thermoneutral zones. Adding the local atmospheric pressure (AP), the parameters were used to calculate the enthalpy (h), resulting in five comfort ranges. Based on this, a decision tree was elaborated, consisting of three attributes (AT, RH, and h) and seven diagnostic classes, based on the psychrometric principles of air. The proposed methodology was used in a case study, with a database extracted from an individual shelter for calves. For the evaluation of the decision tree, two induction algorithms, ID3 and c4.5, were compared, both of which presented high accuracy and proposed simpler tree models than the one theoretically developed for the methodology. In conclusion, the methodology represents a great potential to characterize the thermal comfort of the animals, diagnose the causes of stress, and recommend possible corrective actions. The study revealed that decision trees can be adapted and simplified for each creation phase.

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Metabolic-associated fatty liver disease (MAFLD) is a condition characterized by excessive accumulation of triglycerides in hepatocytes, currently considered the number one cause of chronic liver disease. MAFLD is strongly associated with obesity, type 2 diabetes, hyperlipidaemia, and hypertension. Emphasis has been placed on the use of green tea (GT), produced from the Camellia sinensis plant, rich in antioxidants as polyphenols and catechins, on obesity and MAFLD treatment/prevention. Studies carried out in rodent models housed at a standard temperature (ST, 22°C) are being questioned as ST is a determining factor on generating changes in the physiology of immune response, and energy metabolism. On the other hand, it seems that thermoneutrality (TN, 28°C) represents a closer parallel to human physiology. In this perspective, we investigated the effects of GT (500 mg/kg of body weight, over 12 weeks, 5 days/week) by comparing mice housed at ST or TN in a model of MAFLD of diet-induced obese males C57Bl/6 mice. We show that the liver phenotype at TN exhibits a more severe MAFLD while GT ameliorates this condition. In parallel, GT restores the expression of genes involved in the lipogenic pathway, regardless of temperature, with slight modifications in lipolysis/fatty acid oxidation. We observed an increase promoted by GT in PPARα and PPARγ proteins independently of housing temperature and a dual pattern of bile acid synthesis. Thus, animals' conditioning temperature is a key factor that can interfere in the results involving obesity and MAFLD, although GT has beneficial effects against MAFLD independently of the housing temperature of mice.

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PURPOSE: During obesity, the adipose tissue is usually infiltrated by immune cells which are related to hallmarks of obesity such as systemic inflammation and insulin resistance (IR). Green tea (GT) has been widely studied for its anti-inflammatory actions, including the modulation in the proliferation and activity of immune cells, in addition to preventing cardiovascular and metabolic diseases. METHODS: The aim of the present study was to analyze the population of immune cells present in the subcutaneous and epididymal white adipose tissue (WAT) of mice kept at thermoneutrality (TN) and fed with a high-fat diet (HFD) for 16 weeks, supplemented or not with GT extract (500 mg/kg/12 weeks). RESULTS: The HFD in association with TN has induced chronic inflammation, and IR in parallel with changes in the profile of immune cells in the subcutaneous and epidydimal WAT, increasing pro-inflammatory cytokines release, inflammatory cells infiltration, and fibrotic aspects in WAT. On the other hand, GT prevented body weight gain, in addition to avoiding IR and inflammation, and the consequent tissue fibrosis, maintaining a lower concentration of cytokines and a profile of immune cells similar to the control mice, preventing the harmful modulations induced by both HFD and TN. CONCLUSIONS: GT beneficial effects in WAT abrogated the deleterious effects triggered by HFD and TN, maintaining all immune cells and fibrotic markers at the same level as in lean mice. These results place WAT immune cells population as a potential target of GT action, also highlighting the positive effects of GT in obese mice housed at TN.

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Hypothalamic Agrp neurons regulate food ingestion in adult mice. Whether these neurons are functional before animals start to ingest food is unknown. Here, we studied the functional ontogeny of Agrp neurons during breastfeeding using postnatal day 10 mice. In contrast to adult mice, we show that isolation from the nursing nest, not milk deprivation or ingestion, activated Agrp neurons. Non-nutritive suckling and warm temperatures blunted this effect. Using in vivo fiber photometry, neonatal Agrp neurons showed a rapid increase in activity upon isolation from the nest, an effect rapidly diminished following reunion with littermates. Neonates unable to release GABA from Agrp neurons expressed blunted emission of isolation-induced ultrasonic vocalizations. Chemogenetic overactivation of these neurons further increased emission of these ultrasonic vocalizations, but not milk ingestion. We uncovered important functional properties of hypothalamic Agrp neurons during mouse development, suggesting these neurons facilitate offspring-to-caregiver bonding.

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The objective of this study was to evaluate the behavioral and thermoregulatory characteristics of Dorper sheep. The experiment involved 12 adult females in which the respiratory frequency (RF), heart rate (HR), and rectal temperature (RT) were measured and the following behavioral activities were evaluated: Idling while standing, Idling while lying, Drinking, Ruminating while standing, Ruminating while lying, Defecating, Urinating, Walking, Vocalizing, Biting, Coughing, Playing, Fighting, Rubbing, Self-cleaning, and Sleeping. The physical analysis of the thermal environment in the facility was obtained at the meteorological station of the Technical School of Teresina, where the air temperature (AT) and air relative humidity (ARH) were recorded. The black globe humidity index was obtained using a thermometer inserted in a black globe. A significant difference was detected for AT and ARH, especially the former, which had a higher value in the afternoon period (36.5 ºC). A significant effect was observed for the physiological variables, for which the highest values were found in the afternoon period, as follows: 85.30 mov./min, 93.11 beats/min, and 39.51 ºC (RF, HR, and RT, respectively). Air temperature had positive correlations of 0.572, 0.516, and 0.165 with all thermoregulatory characteristics (RF, HR, and RT, respectively). There was a significant difference for the ‘Idling while standing’, ‘Idling while lying’, ‘Ruminating while lying’, ‘Vocalizing’, ‘Eating’, ‘Playing’, and ‘Sleeping’ behaviors in relation to the evaluated periods of the day. The animals showed a certain level of thermal discomfort, especially in the afternoon period.

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The objective of this study was to evaluate the behavioral and thermoregulatory characteristics of Dorper sheep. The experiment involved 12 adult females in which the respiratory frequency (RF), heart rate (HR), and rectal temperature (RT) were measured and the following behavioral activities were evaluated: Idling while standing, Idling while lying, Drinking, Ruminating while standing, Ruminating while lying, Defecating, Urinating, Walking, Vocalizing, Biting, Coughing, Playing, Fighting, Rubbing, Self-cleaning, and Sleeping. The physical analysis of the thermal environment in the facility was obtained at the meteorological station of the Technical School of Teresina, where the air temperature (AT) and air relative humidity (ARH) were recorded. The black globe humidity index was obtained using a thermometer inserted in a black globe. A significant difference was detected for AT and ARH, especially the former, which had a higher value in the afternoon period (36.5 ºC). A significant effect was observed for the physiological variables, for which the highest values were found in the afternoon period, as follows: 85.30 mov./min, 93.11 beats/min, and 39.51 ºC (RF, HR, and RT, respectively). Air temperature had positive correlations of 0.572, 0.516, and 0.165 with all thermoregulatory characteristics (RF, HR, and RT, respectively). There was a significant difference for the ‘Idling while standing, ‘Idling while lying, ‘Ruminating while lying, ‘Vocalizing, ‘Eating, ‘Playing, and ‘Sleeping behaviors in relation to the evaluated periods of the day. The animals showed a certain level of thermal discomfort, especially in the afternoon period.(AU)

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OBJECTIVE: The induction of beige/brite adipose cells in white adipose tissue (WAT) is associated with protection against high fat diet-induced obesity and insulin resistance in animals. The helix-loop-helix transcription factor Early B-Cell Factor-2 (EBF2) regulates brown adipose tissue development. Here, we asked if EBF2 regulates beige fat cell biogenesis and protects animals against obesity. METHODS: In addition to primary cell culture studies, we used ​Ebf2 knockout mice and mice overexpressing EBF2 in the adipose tissue to study the necessity and sufficiency of EBF2 to induce beiging in vivo. RESULTS: We found that EBF2 is required for beige adipocyte development in mice. Subcutaneous WAT or primary adipose cell cultures from Ebf2 knockout mice did not induce Uncoupling Protein 1 (UCP1) or a thermogenic program following adrenergic stimulation. Conversely, over-expression of EBF2 in adipocyte cultures induced UCP1 expression and a brown-like/beige fat-selective differentiation program. Transgenic expression of Ebf2 in adipose tissues robustly stimulated beige adipocyte development in the WAT of mice, even while housed at thermoneutrality. EBF2 overexpression was sufficient to increase mitochondrial function in WAT and protect animals against high fat diet-induced weight gain. CONCLUSIONS: Taken together, our results demonstrate that EBF2 controls the beiging process and suggest that activation of EBF2 in WAT could be used to reduce obesity.

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In this study we aimed to evaluate the physiological variables of sheep under the influence of Piauí semiarid environment. We used ten Santa Ines rams with black coat. The study was conducted at the small ruminants sector of the Federal University of Piauí, Campus Professora Cinobelina Elvas. Respiratory and cardiac frequencies, rectal temperature and sweating rate were measured.  Temperature, air relative humidity and globe temperature and humidity index were recorded at the Campus weather station. There was a significant difference for all the meteorological variables so that the highest values were observed for the afternoon shift, except for air relative humidity (33.52%). For physiological variables significant effect was observed for respiratory and cardiac frequencies and higher values of these variables were found in the morning shift, with 49,50 breath/min and 89,52 beats/min, respectively. For rectal temperature, significant effect was observed, with the highest values for the afternoon shift (39,92C). We can notice that the animals needed to activate their physiological variables to keep their bodies in thermoneutral zone.

Objetivou-se com este estudo avaliar as variáveis fisiológicas de ovinos sob influência do ambiente semiárido piauiense. Utilizou-se dez ovinos machos da raça Santa Inês, com pelagem preta. O estudo foi conduzido no setor depequenos ruminantes da Universidade Federal do Piauí, Campus Professora Cinobelina Elvas. Foram mensuradas as frequências respiratória e cardíaca, temperatura retal e a taxa de sudação. Na estação meteorológica do campus foram registradas a temperatura e umidade relativa do ar, além do índice de temperatura de globo e umidade. Pode-se observar que houve diferença significativa para todas as variáveis meteorológicas e com os maiores valores para o turno da tarde, exceto para umidade relativa do ar (33,52%). Para asvariáveis fisiológicas foi observado efeito significativo para as frequências respiratória e cardíaca e que valores maiores destas variáveis foram encontradas no turno da manhã, sendo 49,50 resp/min e 89,52 batimentos/min, respectivamente. Para a temperatura retal, foi observado efeito significativo,com os maiores valores para o turno da tarde (39,92°C). Pode-se verificar que foi necessário para os animais acionarem suas variáveis fisiológicas para manter seu corpo em zona de termoneutralidade.

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In this study we aimed to evaluate the physiological variables of sheep under the influence of Piauí semiarid environment. We used ten Santa Ines rams with black coat. The study was conducted at the small ruminants sector of the Federal University of Piauí, Campus Professora Cinobelina Elvas. Respiratory and cardiac frequencies, rectal temperature and sweating rate were measured.  Temperature, air relative humidity and globe temperature and humidity index were recorded at the Campus weather station. There was a significant difference for all the meteorological variables so that the highest values were observed for the afternoon shift, except for air relative humidity (33.52%). For physiological variables significant effect was observed for respiratory and cardiac frequencies and higher values of these variables were found in the morning shift, with 49,50 breath/min and 89,52 beats/min, respectively. For rectal temperature, significant effect was observed, with the highest values for the afternoon shift (39,92C). We can notice that the animals needed to activate their physiological variables to keep their bodies in thermoneutral zone.(AU)

Objetivou-se com este estudo avaliar as variáveis fisiológicas de ovinos sob influência do ambiente semiárido piauiense. Utilizou-se dez ovinos machos da raça Santa Inês, com pelagem preta. O estudo foi conduzido no setor depequenos ruminantes da Universidade Federal do Piauí, Campus Professora Cinobelina Elvas. Foram mensuradas as frequências respiratória e cardíaca, temperatura retal e a taxa de sudação. Na estação meteorológica do campus foram registradas a temperatura e umidade relativa do ar, além do índice de temperatura de globo e umidade. Pode-se observar que houve diferença significativa para todas as variáveis meteorológicas e com os maiores valores para o turno da tarde, exceto para umidade relativa do ar (33,52%). Para asvariáveis fisiológicas foi observado efeito significativo para as frequências respiratória e cardíaca e que valores maiores destas variáveis foram encontradas no turno da manhã, sendo 49,50 resp/min e 89,52 batimentos/min, respectivamente. Para a temperatura retal, foi observado efeito significativo,com os maiores valores para o turno da tarde (39,92°C). Pode-se verificar que foi necessário para os animais acionarem suas variáveis fisiológicas para manter seu corpo em zona de termoneutralidade.(AU)

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We investigated whether or not the preferred ambient temperature (Tapref) of the 1-day old chicken hatchling, a precocial neonate with excellent locomotory capacity, clearly identifiable thermogenesis and independence from maternal care, coincides with the lower critical temperature (LCT) of thermoneutrality and minimal oxygen consumption (V̇(O(2))). Tapref of single chicks measured in a thermocline (N=16) averaged 33.5±0.3 °C (mode, 33.3±0.4 °C). The same value was obtained in hatchlings studied in pairs. LCT was computed from the ambient temperature (Ta)-V̇(O(2)) relationship, constructed by slowly decreasing the Ta of a respirometer from 38 to 29 °C over 2.5h, while continuously measuring V̇(O(2)) by an open-flow methodology; LCT averaged 36.4 °C±0.3 or 36.8 °C±0.4, depending on the method of computation. In all hatchlings Tapref was lower than LCT (P<0.001), by a magnitude that depended on the method of computation of the two variables, 2.8 °C±0.3 (P<0.001) or 3.9 °C±0.5. The Tapref-LCT difference implied that, at Tapref, V̇(O(2)) was higher than at thermoneutrality. We conclude that in the chicken hatchling thermal preference does not coincide with thermoneutrality, probably because during development what seems optimal from a thermoregulatory viewpoint may not necessarily be so for other regulatory functions.

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Determinou-se a exigência de aminoácidos sulfurados para suínos machos castrados, mantidos em ambiente termoneutro, dos 15 aos 30kg. Utilizaram-se 70 leitões mestiços, distribuídos em delineamento experimental de blocos ao acaso, com cinco tratamentos (0,465; 0,511; 0,558; 0,605 e 0,652% de metionina + cistina digestível), sete repetições e dois animais por repetição. As rações experimentais e a água foram fornecidas à vontade. A temperatura no interior da sala foi mantida em 21,8±0,4ºC e a umidade relativa, em 73,8±4,9%. Os níveis de metionina + cistina digestível da dieta influenciaram de forma quadrática o ganho de peso diário, que aumentou até o nível de 0,596%, e a conversão alimentar, que reduziu até o nível de 0,627%. O consumo de ração dos animais não variou com os tratamentos. Os tratamentos influenciaram a deposição de proteína na carcaça, que aumentou de forma quadrática até o nível de 0,630%, enquanto a de gordura não variou. A exigência de aminoácidos sulfurados digestíveis para suínos machos castrados, mantidos em ambiente termoneutro, dos 15 aos 30 kg, é de 0,63%, correspondente à relação metionina + cistina digestível:lisina digestível de 67%, para máximo desempenho e composição de ganho.(AU)

The requirements of digestible sulphurous aminoacids for swine barrows maintained in a thermoneutral environment from 15 to 30kg were estimated. Seventy crossbred barrows were allotted to a completely randomized block design with five treatments (0.465; 0.511; 0.558; 0.605; 0.652% of digestible methionine+cystine), seven replicates and two animals by replicate. The experimental diets and the water were supplied ad libitum. The inside room temperature was maintained in 21.8±0.4ºC and the relative humidity in 73.8±4.9%. The digestible methionine and cystine levels of the diet had a quadratic effect on average daily gain that increased until the level of 0.596% and the feed:gain ratio that reduced quadraticaly until the level of 0.627%. No effect of digestible aminoacid on feed intake was observed. The treatments affected protein deposition in the carcass that increased quadraticaly until the level of 0.630%, but had no effect on fat deposition. The digestible sulphurous aminoacids requirement for barrows maintained in a thermoneutral environment from 15 to 30kg was 0.63%, which corresponds to digestible methionine and cystine:digestible lysine ratio of 67%, respectively, for highest performance and gain composition.(AU)

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