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Coat color is a factor affecting heat tolerance in tropical ruminant and a particular coat color can determine which is more resilient to environmental changes. The aim of this study was to measure the level of adaptation of Morada Nova sheep with different coat color by using an Adaptability Index (AI). Adult ewes were used, including two different coat colors of Morada Nova sheep (red and white) with mean of body weight of 28.02 ± 5.70 kg and 31.47 ± 3.41 kg, respectively. Physiology parameters, hematology, electrolytes, acid-base status, mineral, renal functions, metabolites, enzymes, and proteins were measured. AI was designed using a multivariate approach (principal component analysis) to "weigh" the influence of each variable in the animal responses. The variables more important for adaptive aspects of Red Morada Nova were: haematology, electrolytes and acid-base status. The hemoglobin (HG), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), sodium (Na + ), oxygen pressure (PO 2 ), glucose (GLU) and albumin (ALB) were significantly higher in Red Morada Nova sheep and hydrogen carbonate (HCO 3 ), base excess (BE), total carbon dioxide concentration (TCO 2 ) and URE were significantly higher in the white phenotype. The variables more important for adaptive aspects of White Morada Nova sheep were: (K + ), total protein (TP), PO 2 , HG, cholesterol (CHO), rectal temperature (RT) and glucose (GLU). Both phenotypes showed a high adaptation level, however, a higher value was generated for the Red Morada Nova sheep (81.97). This study concludes that both phenotypes of the Morada Nova sheep breed are well adapted to the climatic condition of the Brazilian tropical region using different adaptive mechanisms., (© 2024. The Author(s) under exclusive licence to International Society of Biometeorology.)

This study aimed to evaluate and compare the physiological performance of different genetic groups of sheep, by physiological variables and serum hormone levels, in a hot weather environment. Thirty sheep from five genetic groups were used: Santa Inês (SI), ½ Dorper + ½ Santa Inês (DO), ½ Ilê de France + ½ Santa Inês (IF), ½ Suffolk + ½ Santa Inês (SK), and ½ Texel + ½ Santa Inês (TX). The readings and records of physiological parameters (respiratory rate (RR), rectal temperature (RT), auricular cavity temperature (ACT), and surface temperature (ST)) were carried out at 7:00 am, 1:00 pm, and 7:00 pm, in 12 non-consecutive days. The collections of blood samples for hormone analysis (triiodothyronine (T 3 ), thyroxine (T 4 ), and cortisol (CORT)) is in four consecutive days. The environmental conditions of the experimental period caused a thermal discomfort in the sheep, but not a state of thermal stress. The thermolysis mechanisms, sensitive (ST and ACT) and latent (RR) processes, were enough to maintain their homeostasis (RT). The results showed that crossbred breeds presented a higher metabolism and were more efficient at dissipating heat through thermolysis than the SI breed. The crossbred breeds were efficient at dissipating heat through the elevation of body surface temperature and respiratory rate, mainly SK and TX, i.e., crossbred breeds, despite the wool cover, used thermoregulatory mechanisms that promoted lower variation of RT. The analysis of variance showed significant effects (P < 0.05) to the time factor in the responses of T 4 and T 3 , and to the breed factor in the responses of CORT, T 4 , and T 3 . We did not observe interaction between the factors to any of the hormonal variables. Therefore, we can state that the effect of time was independent of breed and vice versa. Thyroid hormones presented lower blood concentration in the mornings (4.03 ± 0.82, T 4 ; 65.08 ± 10.6, T 3 ), increasing their concentration in the afternoon (4.60 ± 1.03, T 4 ; 70.16 ± 14.17, T 3 ). The thyroid hormones presented a normal circadian rhythm, with the exception of SK. Air temperature (AT) showed greater correlation with physiological variables than enthalpy (H) did, in the experimental conditions. However, H showed correlation with T 4 and T 3 . The adaptive profile of the genetic groups under study are different, but the IF genetic group showed better performance under environmental conditions., (© 2023. The Author(s) under exclusive licence to International Society of Biometeorology.)

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., (© 2023. The Author(s) under exclusive licence to International Society of Biometeorology.)

The objective of the study was to characterize the adaptive profile of Ibero-American sheep of the Canaria breed, evaluating the possible changes in thermoregulatory responses and coat characteristics to which the animals are exposed in the different seasons of the year. Data collected over a period of 12 months were analyzed, with information being observed in the interval of 15 days of each month, in 23 adult ewes kept in an intensive breeding system. The rectal temperature (RT) of Canaria ewes was higher (P < 0.001) in the summer and spring seasons. In contrast, the respiratory rate (RR) of the animals was higher in autumn. The surface temperature (ST) of the herd was lower during the spring. It was observed that the hair length (HL) and the hair density (NH) did not vary during the seasons. However, the hair diameter (HD) and the coat thickness (CT) varied, being in the spring, the season in which the animals had the highest HD and autumn, the season in which they had the lowest. The performance was similar throughout the seasons (P > 0.05). The morphological variables of the coat presented 63.8% of original cases grouped, which may characterize the morphological responses of the coat of these animals as an important trait of the adaptive profile of the breed, whereas the opposite occurred for thermoregulatory responses. The variables most used by the herd and that were most important were autumn (CT, NH, HD, HR, RT, and HL), summer (ST and RR), spring (RR, ST, and RT), and winter (RT, HD, HR, and RR). Sheep of the Canaria breed have an adaptive profile that dynamically uses thermoregulatory and morphological responses, molding themselves according to climate changes resulting from seasonal periods on the Island of Tenerife, Spain. The Canaria sheep stood out for the modification of the morphological characteristics of the coat, especially during autumn and spring, and can be considered an excellent genetic resource with excellent adaptive characteristics for arid environments such as those found in the Canary Islands., (© 2023. The Author(s) under exclusive licence to International Society of Biometeorology.)

For all the benefits of a compost barn system to be achieved, the management, especially with the bedding, must be done correctly. One should consider the requirements regarding the revolving of the material, use of good quality organic matter, suitable ventilation, and an ideal animal stocking rate, so that the composting occurs efficiently. Given this, this work aimed to evaluate the spatial variability of thermal characteristics of rice straw bedding, using values of temperature (surface and internal) and humidity. The temperature and moisture values of the litter were recorded at intervals during the morning shift, from 6:00 am to 7:00 am and from 8:00 am to 9:00 am, and during the afternoon shift, from 3:00 pm to 4:00 pm and from 5:00 pm to 6:00 pm, considering the management of the turn-over, that is, before and after the movement of the litter. Litter variables were collected at points distributed on a 39-point grid. There were no differences between litter surface temperatures before and after turning over in the morning shift, but in the afternoon shift, the surface temperature was lower (P < 0.05) before, when compared to after turning. The internal temperature and litter moisture were higher (P < 0.05) before revolving in both shifts. Spatial dependence was verified (IDE) for the variables studied. Based on the geostatistical analysis, it is concluded that the IDE was rated as strong for surface and internal temperatures, which demonstrates heterogeneity among the points evaluated and a large spatial variability regarding bed temperatures. In the case of litter moisture, the greatest variability occurred in the morning period. The litter surface temperature values did not exceed the ambient air temperature values., (© 2023. The Author(s) under exclusive licence to International Society of Biometeorology.)

A commercial low-profile cross-ventilated system (LPCV) free-stall barn with evaporative cooling pads on the air intake side was used to assess the potential of cross-ventilation with evaporative cooling to alleviate heat stress in lactating dairy cows. A total of 5712 records (238 days × 24 h) of air temperature (AT) and relative humidity (RH) values were collected. In order to state the effectiveness of the ventilation system and potential heat stress, the temperature humidity index (THI) and enthalpy (h) were calculated outside and inside the LPCV barn. The cooling capacity of the LPCV system is greater in conditions of low humidity, and the difference between the values of the internal and external temperature reached -12 °C. The LPCV reduced exposure to heat stress, increasing the time cows spent in thermoneutral conditions. This system could reduce the occurrence of temperature above 25 °C from 33 to 5% and 11% in sections A (represents the inlet side of the barn) and D (represents the outlet side of the barn), respectively. On the other hand, the LPCV kept a high and constant rate of RH throughout the day. The average inside and outside AT were significantly different, but differences in temperature were observed across the width of the barn. Analyzing the barn by the indexes, the THI showed that the barn promoted cows more time confined under non-stressful thermal conditions (between 83.8 and 90% vs 68.7%) and stress period much lower compared to the external environment (between 10 and 16.2% vs. 31.3%). The enthalpy index showed that there was not much difference between the internal and external environments. The LPCV system is another installation alternative for raising dairy cow in a hot and humid climate., (© 2023. The Author(s) under exclusive licence to International Society of Biometeorology.)

This study's objective was to evaluate the thermoregulation aspects of native goats through broken-line regression to understand the triggering of physiological responses in the homeothermy process. Data were collected from ten healthy dams of the Canindé breed once a week at hourly intervals (24 h) for eight consecutive weeks. Air temperature (AT; °C), relative humidity (RH; %) were measured and temperature-humidity index (THI) calculated. The thermoregulation parameters evaluated were: respiratory rate (RR; breaths.min -1 ), rectal temperature (RT; °C) and sweating rate (SR; g.m -2 .h -1 ). All variables were subjected to analysis of variance with repeated measures over time. The hour was considered a fixed effect (00:00 h, 01:00 h, …, 23:00 h), and the animal was a random effect. Multiple regression analyses were also examined using General Linear Models and Variance Inflation Factors were calculated. Broken line non-linear regressions for RR, RT and SR were examined using independent variables. The highest average for AT and RH were 35.9 °C (13:00 h) and 92.4% (04:00 h), respectively. The lowest average of TA and RH were 22.1 °C (05:00 h) and 28.0% (12:00 h), respectively. The highest average THI was 102.1 (13:00 h), and the lowest 78.0 (05:00 h). The environmental thresholds at which RR, RT and SR began to increase for AT were between 17-21 °C and RH were > 17% (RR), ≥ 21 (RT) and > 23% (SR). For THI the limits were 108.4 for RR, 78.0 for RT and 100.1 for SR. Using THI, the thermoregulatory parameters are activated in the following order: SR, RR and RT. Estimates can serve as a basis to implement heat stress mitigation and improve animal welfare strategies for native goats., (© 2023. The Author(s) under exclusive licence to International Society of Biometeorology.)

The compost barn is presented as a system which is capable of providing a suitable environment for dairy cows, but this must be assessed for different climatic regions. Few studies have been carried out evaluating the physics of the thermal environment of this system under tropical conditions. In this study, we evaluated thermoregulatory, behavioral, and productive responses and physical integrity in primiparous and multiparous cows housed in a compost barn system under tropical conditions. From a total of 121 clinically healthy dairy cows aged 3 to 6 years, 30 Girolando cows (7/8) were randomly selected, divided into two groups, according to calving order (primiparous and multiparous), body weight, lactation curve and milk production for the evaluations. Thus, group 1 (primiparous) with an average weight of 524 kg and production of 30 kg was characterized, and group 2 (multiparous) with an average weight and production of 635 kg and 36 kg, respectively. The enthalpy was higher (P < 0.05) in the internal environment of the shed at the three evaluated times (3:30 a.m., 11:30 a.m., and 6:30 p.m.), but the humidity did not vary (P > 0.05) between the internal and external environments at the evaluated times. Respiratory rate was higher (P < 0.0001) in multiparous cows at 11:30 a.m., but was similar at 3:30 a.m. and 6:30 p.m. when compared with primiparous cows. The coat surface temperature was higher (P < 0.001) at 3:30 a.m., but similar at the other two times. For the variables lameness and dirtiness, the vast majority of animals presented scores considered adequate (1 and 2), indicating that it was able to provide an ideal physical environment. Regarding animal behavior, panting (O) and lying idle (OD) were higher (P < 0.05) in multiparous cows. Multiparous cows have higher (P < 0.0001) milk production. Milk production has a negative correlation with enthalpy. The CB system was not able to provide a suitable thermal environment for the animals. Multiparous cows present higher heat stress with change in behavioral responses, especially at midday, but with higher milk production when compared to primiparous cows in compost barn under tropical conditions., (© 2023. The Author(s) under exclusive licence to International Society of Biometeorology.)

Due to the high milk production of Holstein cows, many countries have chosen to import semen to improve local dairy herds. This strategy would be more effective if this semen was used in the same environment conditions in which the bulls were selected. If the effect of genotype by environment (G × E) interaction is not considered, the estimated breeding values (EBVs) may vary, potentially reducing the selection response. We evaluate the impact of heat stress on selection for milk yield and composition of Holstein cows using random regression models. To verify the interference of heat stress in milk yield (MY) and composition traits (fat, protein, total saturated, and total unsaturated fatty acids content in milk), temperature-humidity index (THI) on test-day milk records was used. The threshold value to divide the environments using test-day information from Brazilian Holstein cows was 72 units of THI, i.e., < 72 represented no heat stress and > 72 represented heat stress. Legendre polynomials of second-order (Leg 2) model and two lactation points (33 and 122 DIM) were used to estimate heritabilities and EBVs for five important dairy traits. The heritabilities of milk components and fatty acids were low (0.09-0.29), regardless of lactation period and degree of heat stress, with the exception of protein content (0.30-0.35). Fat content was the only milk component that was reduced according to the degree of heat stress and lactation period. The EBVs tended to decrease in heat stress conditions, thus animals with high genetic potential demonstrated evidence of G × E interaction. However, acclimatization of dairy cows to heat stress in the farm production systems may have been responsible for the low differences among genetic parameters and EBVs with and without heat stress found in this study., (© 2022. The Author(s) under exclusive licence to International Society of Biometeorology.)

The aim of this study was to gain insights in respect to how locally adapted goats exhibit dynamic body heat in an equatorial semi-arid environment. Ten Canindé goats were used in the study (22.90 ± 2.70 kg). Respiratory rate (R R ; min breaths -1 ), rectal temperature (R T ; °C) and sweating rate (S R ; g m -2  h -1 ) were measured for 8 days, once a week, for 8 consecutive weeks in each animal, with collection intervals of 1 h throughout the day (24 h), together with the meteorological variables. Air temperature (A T , °C) and relative humidity (R H , %) were measured, and then, the temperature humidity index (T HI ) was calculated. First, we determined 2 days with stressful climatic conditions and similar environmental characteristics (day 1 and 2) among the 8 experimental days. The R T was evaluated on these 2 days using the means of each hour as the cut-off point, and determining whether the animals are efficient (EF) or inefficient (INEF) in heat loss (β 1 ) and gain (β 2 ). The R T was separated in β 1 and β 2 for 24 h, setting times to obtain the angular coefficients (β) for both. The days with stressful climatic conditions and similar environmental characteristics were day 1 and 2. The hours in which the Canindé goats gained and lost heat were respectively 11 a.m. to 3 p.m. and from 4 p.m. to 10 a.m. The animals classified as EF lost more or equal the amount of heat represented for R T . When the mean of all animals was evaluated for efficiency in heat control, the flock was classified as EF. Differences (P < 0.05) were observed for R R and S R between periods. The efficiency in dynamic body heat of the locally adapted goats in this study was determined and showed that the flock as a whole possesses an excellent heat dynamic in an equatorial semi-arid environment.

The objectives of this study were to determine the main variables which act in the adaptive profile and the dynamic of the thermoregulatory responses of Sindi and Girolando dairy cows in tropical conditions using multivariate analyses as the auxiliary method. Thirty dairy cows were evaluated, in which the data were collected monthly during 12 months. Rectal temperature (R T ) and respiratory rate (R R ) were measured twice a day (morning and afternoon), along with meteorological variables (air temperature, relative humidity, and wind speed), and later the Black Globe and Humidity Index and Radiant Heat Load were calculated. Blood samples were collected for estimating the levels of triiodothyronine (T 3 ), thyroxine (T 4 ), hemoglobin concentration (HC), red blood cells (RBC), packet cell volume (PCV), mean corpuscular volume (MCV), white blood cells (WBC), glucose (GLU), cholesterol (CHO), triglycerides (TRI), creatinine (CRE), total protein (TP), urea (URE), albumin (ALB), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). The more active variables in the adaptive profile for Sindi cows were T 4 , PCV, RBC, WBC, TRI, CRE, HC, T 3 , and URE, while PCV, RBC, ALB, TP, R T , R R , URE, ALT, and AST variables were more active for Girolando cows. All animals were classified according to their corresponding group when considering all variables under study. The classification error percentage was > 40% in the Sindi cows when the physiological responses were considered, whereas an 80% success rate was observed in Girolando cows in the winter and summer seasons. The physiological responses of the dairy cows are similar in winter and distinct in summer in tropical conditions.