Black Globe Temperature And Humidity Index Research Articles

Bioclimatic thermal stress indices and their relationships with andrological characteristics in hair rams.

This study evaluated relationships among reproductive parameters and the bioclimatic indices: temperature and humidity index (THI), equivalent temperature index (ETI), black globe temperature and humidity index (BGTHI), and thermal comfort index (TCI), during the first 45 days of spermatogenesis (SP-45) and during the 15 days of sperm transit through the epididymis (STP-15) that preceded the reproductive assessments (ReA). Such information is useful in determining the optimal breeding season in Northeast Brazil. Santa Inês rams (n = 25) underwent two ReA in three periods of the year (D-P = dry; R-P = rainy and RD-P = rainy/dry transition), and the bioclimatic indices were calculated at the corresponding SP-45 and STP-15 timepoints prior to each ReA. Sperm kinetic parameters in D-P were depressed compared to R-P and RD-P (P < 0.05). The index values had an antagonistic relationship with most parameters and regression analysis demonstrated that the BGTHI and the TCI had a negative association with the progressive motility, curvilinear, straight line, and average path velocities, and a positive association with slow sperm in the ejaculate in SP-45 and STP-15 phases (P < 0.01). Semen quality kinetics is affected throughout the year by the environment and it is apparent that it is impaired in D-P and better in R-P and RD-P seasons. The BGTHI and TCI measured in the sperm production phase classified the environment most coherently and presented better association with the behavior of sperm kinetics.

Physiological responses of Santa Inês x Dorper ewes and lambs to thermal environment of silvopasture and open pasture systems

The silvopasture is a sustainable livestock system, which has great potential for sheep, mainly focused on the thermal comfort and welfare of animals. However, there is a lack of information regarding the thermal environment and physiology of ewes and lambs raised in this system. This study was therefore aimed at assessing the influence of microclimate on the thermal comfort of postpartum ewes and lambs kept in silvopastoral (SP) or open pasture (OP) systems during the summer. Postpartum crossbred ewes (Santa Inês x Dorper; n = 24) and their lambs (n = 24) were randomly allocated to SP or OP group, being distributed into four paddocks per group (three ewes and three lambs per paddock). The microclimate characterization measured were dry-bulb ambient temperature (Ta, ºC), black globe temperature (Tbg, ºC), relative humidity (RH, %), grass temperature (Tg, ºC) and wind speed (WS, m s−1). These variables were then applied to calculate the temperature and humidity index (THI), black globe temperature and humidity index (BGHI), and radiant heat load (RHL). To assess the thermophysiology response, the respiratory rate (RR, breaths min−1), heart rate (HR, beat min−1), rectal temperature (RT, ºC), and hair coat surface temperature (ST, ºC) were analyzed. Regarding the microclimate variables, Ta and Tg were higher in OP than in SP (P = 0.008 and P < 0.001, respectively), while SP presented higher RH values (P = 0.037). There was no significant difference in WS between the systems (P = 0.288). As expected, all indices showed lower mean values in SP compared to OP, mainly the radiant heal load (P < 0.001). Regarding the thermophysiology response, the RR of ewes was significantly higher in OP (129 ± 4.5 breaths min−1) than in SP (85 ± 4.7 breaths min−1) (P < 0.001). The RT was higher in the OP, but only in the afternoon (P < 0.001). Meanwhile, lambs in OP also presented higher RR (105 ± 3.5 breaths min−1) and RT (39.9 ± 0.1 °C) values than in SP (74 ± 2.8 breaths min−1 and 39.9 ± 0.1 °C, respectively). Following the prior trends, during the afternoon lambs showed higher values of RR than in the morning. However, the difference between those periods was small for RT. The ST of ewes in SP was lower compared to ewes in OP (P < 0.001). In the afternoon, the difference of ewes in SP had ST 4.3 °C lower compared to OP, while for lambs, the ST in the afternoon increased by 5.3 °C more in OP than in SP. The study suggests that the presence of trees reduced hyperthermia for both ewes and lambs further supporting the SP as a sustainable farming system that promotes thermal comfort and welfare for small ruminants.

Ingestive behavior and infrared thermography of Holstein × Zebu crossbreed cows in the final third of gestation in different pastoral environments

This study aimed to evaluate the ingestive behavior and body surface temperature of F1 Holstein × Zebu cows that were non-lactating in the final third of gestation and managed in two pastoral environments. Forty F1 Holstein × Zebu cows divided into two pastoral environments were evaluated: signal grass (Urochloadecumbens cv. Basilisk) deferred at the beginning of regrowth and pasture of xaraés grass (Urochloa brizantha cv. Xaraés) in vegetative growth in four periods during the day (morning, afternoon, night and dawn), following the completely randomized design in a factorial scheme. Each cow is the experimental unit. The total grazing time was 32.22% higher in the signal grass than xaraés grass (average of 479.50 minutes). There was an interaction between the pastoral environments and the periods on the black globe temperature and humidity index (BGHI). In the pasture of signal grass, the BGHI was 19.07% higher in the morning and afternoon periods than the average (68.95) verified during the night and dawn. F1 Holstein × Zebu cows grazing time in the final third of gestation is influenced by the pasture condition and not by the climate since they feed in a high BGHI environment.

BEHAVIOR OF BROILERS UNDER THE INFLUENCE OF LED LIGHTING AND MICROMETEOROLOGICAL ELEMENTS

ABSTRACT The objective of this research was to analyze the differences between the food behaviors observed under the factors of production environment, sex and lighting system, using stochastic tools of multivariate analysis. As for the thermal characteristics of the environment, air temperature (T, °C), enthalpy (H, kJ kg-1), and black globe temperature and humidity index (BGTHI) showed high positive correlation with each other and strong negative correlation with relative humidity (RH, %). The “male drinking” behavior was positively associated with thermal characteristics of the environment in the three periods of the day, that is, the act of drinking more water would be a way to alleviate thermal stress. Birds subjected to red LED showed a strong negative correlation with temperature associated with the “female drinking” behavior, in the afternoon period, according to the principal component analysis, which is justified by the orientation of the broiler house with its longitudinal axis in the NE/SW direction, so the sunlight directly hits the area where the drinker was located. Variation in body weight showed better response when the birds were exposed to a temperature of 27 °C, for the 5th week of the rearing cycle.

Black globe temperature from meteorological data and a bioclimatic analysis of the Brazilian Northeast for Saanen goats.

The black globe temperature (BGT) is not a common measurement for weather station networks, despite having great relevance to bioclimatic studies. The aim of this study was to propose equations for estimating the BGT, using meteorological data for different time scales and a bioclimatic evaluation of the Brazilian Northeast for breeding Saanen dairy goats. The data used in elaborating the equations were collected between 1 November 2014 and 31 October 2017. Data for BGT, incident global solar radiation (SR), air temperature (AT), relative humidity (RH) and wind speed were handled on a daytime, night-time, daily and monthly scale. One half of the database was used to adjust the equations and the other half in the evaluation. The bioclimatic diagnosis of the Brazilian Northeast was carried out based on mean monthly values of the black globe temperature and humidity index (BGHI) estimated for the four seasons of the year. For the daytime scale, an equation based on AT (BGT = 1.3897.AT-5.4421, r2=0.80) and a multiplicative model combining the effects of AT and SR (BGT=[1.3897.AT-5.4421] (0.0384.ln(SR)+0.7935], r2 = 0.91) were obtained. AT adjusted well for BGT on the night-time scale (BGT = 0.995.AT-0.6964, r2 = 0.99), daily scale (BGT = 1.1641.AT-1.5941, r2 = 0.97) and monthly scale (BGT = 1.1550.AT-1.3498, r2 = 0.98). The BGT can therefore be calculated from AT and/or SR for the daytime scale, and from AT only for the night-time, daily and monthly scales. In general, the west and centre-south of the state of Bahia offer the animals the most thermal comfort during each season of the year. In the state of Maranhão, heat stress occurs throughout the year, with the BGTI predominately in the range of 85-95. As such, strategies to combat heat stress should be encouraged to minimise the negative effects of climate on milk production in Saanen goats, and favour the milk-production chain in the northeast of Brazil.

Application of microchip and infrared thermography for monitoring body temperature of beef cattle kept on pasture.

The monitoring of body temperature is important for the diagnosis of the physiological state of the animal, being dependent on available methods and their applicability within production systems. This work evaluated techniques to monitor the body temperature of beef cattle kept on pasture and their ability to predict internal temperature. Twenty-three adult bovine females were monitored for six months, and collection data carried out in eleven campaigns (D0-D10) twelve days apart. During collections, the surface temperatures of ear base (ET, oC) and ocular globe (OGT, oC) were measured by infrared thermography, and the subcutaneous temperature (ST, oC) was measured with the use of transponder containing an implantable microchip. Rectal temperature (RT, oC) was considered as a reference for body temperature. Temperature and Humidity Index (THI), Black Globe Temperature and Humidity Index (BGHI) and Radiant Heat Load (RHL, W/m2) were calculated. ET (33.32 ± 0.12 °C), ST (36.10 ± 0.07 °C), OGT (37.40 ± 0.06 °C) and RT (38.83 ± 0.03 °C) differed significantly (P˂0.05). There was positive correlation of RT with OGT (r = 0.392), ET (r = 0.264) and ST (r = 0.236) (P˂0.05). Considering the bioclimatic indicators, the highest magnitude correlations were observed between ET and THI (r = 0.71), ET and BGHI (r = 0.65), and ET and RHL (r = 0.48). The use of microchip represented a practical method, but with limited predictability. On the other hand, infrared thermography proved to be safe and non-invasive, presenting greater precision for inference of internal body temperature. ET was more influenced by meteorological conditions.

Effect of the environment and diet on the physiological variables of sheep in the Brazilian semi-arid region

This study aimed to evaluate and compare the physiological variables of three sheep genotypes: Morada Nova, Somalis, and Dorper x Somalis crossbreed regarding the environment and diet in the Brazilian semi-arid region by using 30 animals (10 from each genetic group). Five of these animals had 30% of the tifton hay replaced by hairy woodrose hay. The temperature and relative air humidity were registered, the black globe temperature and humidity index (BGHI) was calculated, and the rectal temperature (RT), respiratory rate (RR), heart rate (HR), and surface temperature (ST) were measured in the morning and afternoon. The experimental design was a completely randomized design in a 3 × 2 × 2 factorial scheme, which consisted of three genotypes, two diets, and two periods, and five replications each. BGHI presented values of 81 in the shade and 90 in the sun and a significant difference (P &lt; 0.05) was observed for the studied variables in relation to the periods, with higher values in the afternoon. The average ST was 35.48 °C in the morning and 38.11 °C in the afternoon. Morada Nova presented the lowest RT and RR (P &lt; 0.05) among the genetic groups, with a higher tolerance to heat. The 30% substitution of tifton hay by hairy woodrose hay did not negatively affect the thermoregulatory capacity of sheep. The studied genetic groups were adapted and tolerant to climate conditions of the Brazilian semi-arid region.

Welfare and spatial distribution of noise levels in swine nursery

ABSTRACT The aim of this study was to evaluate the welfare and spatial distribution of noise levels in a swine nursery during the first three weeks of animal’s life. The climatic conditions were evaluated through the dry-bulb temperature (Tdb), relative humidity (RH) and black globe temperature and humidity index (BGHI) and allowed us to observe that the heating system influenced the conditions in the environment, and the use of the air conditioning system did not guarantee animal’s comfort conditions. The analysis on the spatial distribution of noise levels was performed using geostatistics and demonstrated the occurrence of spatial variability inside the facilities. The highest frequencies of noise levels were concentrated between 60 and 70 dB, and the highest noise values were observed near the fans. The mean BGHI values were below the thermal comfort range for piglets in all systems tested.

Animal thermal comfort indexes in silvopastoral systems with different tree arrangements

This study aimed to assess solar radiation transmission and animal thermal comfort indexes in two silvopastoral systems established with different tree arrangements in a tropical region. This study was conducted between 2014 and 2017 in two silvopastoral systems, one composed by an established Urochloa (syn. Brachiaria) decumbens pasture with Brazilian native trees planted in triple rows spaced 17 m apart, and another by an established Urochloa (syn. Brachiaria) brizantha (Hochst ex A. Rich.) Stapf ‘BRS Piatã’ pasture with Eucalyptus urograndis (clone GG100) trees arranged in single rows spaced 15 m apart. In these systems and in a full-sun pasture, photosynthetically active radiation transmission, air temperature, relative humidity, black globe temperature, and wind speed were measured. These variables were used to calculate black globe temperature and humidity index (BGHI) and radiant thermal load (RTL). Higher animal thermal comfort was observed in the silvopastoral systems due to changes in the microclimate induced by the trees; notably, a decrease in solar radiation transmission. Fewer hours of potential animal thermal stress (BGHI>79) were observed in the silvopastoral systems than under the full-sun conditions, with differences up to 3 h per day. The silvopastoral systems presented lower radiant thermal load than the full-sun pasture with differences up to 22% achieved. The assessed silvopastoral systems may help livestock adapt to climate change, since they achieved the limit of BGHI considered to cause stress to animals following an increase of 2.2 °C in air temperature, compared with full-sun pastures.

Influência do ambiente térmico no comportamento e desempenho zootécnico de suínos

Environmental modifiers, such as the use of water blade, are often used to produce pigs in order to improve welfare conditions and consequently production. In view of this consideration, we sought to evaluate the effect of the climatic environment on the weight gain and the behavior of pigs in the finishing phase in stalls with and without access to the water blade. The work was conducted in a pig farm located in the city of Nova Porteirinha, located in the semi-arid region of Minas Gerais. In order to evaluate the thermal comfort of the animals, the Black Globe Temperature and Humidity Index (BGHI) was used to evaluate the thermal comfort of the animals and to analyze the behavior of the pigs, the number of animals performing the activity, for the period evaluated, as well as the gain of weight were observed. In the 3rd block, black globe temperature and humidity index values were higher, with lower average daily weight gain. The treatments resulted in different behavioral responses, with water blade behavior being more expressive in the afternoon. The evaluation period showed that to influence surface temperature and at high temperatures the animals presented lower daily average weight gain. The water table did not influence the animals' weight gain, however, it provided better welfare conditions.

SIMILITUDE AND THERMAL PERFORMANCE ON NON-CONVENTIONAL ROOFS

The objectives of this study were to evaluate the thermal comfort and the similitude between prototypes and reduced models, using non-conventional coverage with green roof and expanded clay aggregate, supported on wood frame structure. For this, were determined the Black Globe Temperature and Humidity Index (BGHI), the Human Discomfort Index (HDI), Effective Temperature (ET), Air Temperature (Tair) and Radiant Thermal Load (RTL), from March 2013 to December 2014. The results showed that there were no statistical differences to 5% significance in predicting heat indices between the prototypes and models. Observing all indexes simultaneously, it was observed that January was the month what led to the worst heat conditions, while June and July showed the worst cold conditions. It can be concluded that the use of reduced models is possible (1:2) compared to the prototype (1:1), with green roofs and expanded clay as covering element, for the prediction of thermal indexes, minimizing construction costs and use of spaces.

CONFORTO TÉRMICO EM ABRIGO INDIVIDUAL PARA BEZERROS COM FORRO NÃO CONVENCIONAL DE SUBPRODUTOS AGROINDUSTRIAIS

This study evaluated the thermal comfort conditions in two individuals calve shelter models covered with fiber cement tile without ceiling and using a ceiling made of low density particleboards from agro-industrial by-products (40% sugarcane bagasse and 60% Pinus sp. shavings) bonded with polyurethane bi-component resin based on castor oil. In the ambience study, dry bulb temperature (DBT), black globe temperature (BGT) and relative humidity (RH) of the calf hutches were evaluated. Indices, such as Black Globe Temperature and Humidity Index (BGHI) and Radiant Thermal Load (RTL), and also thermographic images of the internal surface of the shelters were studied. The use of fuzzy modeling has been proposed, allowing the comparison of the BGT, BGHI and RTL indices, and via these values, attributing the comfort situation, thus seeking to optimize the experimental evaluations. The results indicate that the presence of the ceiling did not contribute to a heat level reduction inside the shelters, which presented above the comfort conditions for the animals during the summer. Through observation, there was a reduction of the internal temperature of the surfaces of the shelter with a ceiling.

BIOCLIMATIC LIVESTOCK ZONING OF MARANHÃO STATE, BRAZIL

&lt;p&gt;The production environment in which animals are kept can be classified by bioclimatic indexes expressing the conditions of thermal comfort to different species. In the state of Maranhão (MA), located in Northeast Brazil region, stand out in the livestock sector the beef cattle, pig and poultry production. In order to check the conditions of thermal comfort in the state for these species was held a bioclimatic zoning, taking into account the temperature and humidity index (THI) and Black Globe Temperature and Humidity Index (BGTHI). Estimates of the indexes were performed from meteorological data obtained from the database of the National Institute of Meteorology (INMET). Seven county were considered, and were chosen taking into account the greater amount of information available over the years. The variables analyzed were: air temperature, relative humidity and atmospheric pressure. Bioclimatic indexes were determined by using mathematical equations applied in Microsoft Excel®. Using the Surfer 8.0® program, were generated maps with bioclimatic zones to the state. Taking into consideration the comfort levels recommended as safe for poultry, pigs and cattle in all stages of production (THI 70-74 and BGTHI 72-75), the analyzed bioclimatic zones showed no conditions for comfort and optimal performance of these species, considering that the THI ranged from 74.1 to 75.8. and BGTHI from 80.0 to 82.3. Can be concluded that in the cities checked, the production systems of these species need investment in measures to promote the correction of microclimate to establish optimal levels of animals thermal comfort.&lt;/p&gt;

Thermal comfort indices assessed in integrated production systems in the Brazilian savannah

The objective was to evaluate the animal thermal comfort indices from two integrated croplivestock- forestry (ICLF) systems. For this, temperature? humidity index (THI), black globe temperature and humidity index (BGHI), and the radiant thermal load (RTL) were assessed. Two ICLF (ICLF-1 and ICLF-2) systems and one control system were established. On the ICLF systems, the arboreal component was the eucalyptus tree (Eucalyptus grandis 9 Eucalyptus urophylla; H13 clone), planted in simple widespaced rows. The ICLF-1 system had a tree spacing of 14 9 2 m with 357 trees per hectare, and the ICLF-2 had a tree spacing of 22 9 2 m with 227 trees per hectare. The control system had five scattered native trees per hectare, pertaining to Gochnatia and Dipteryx species. The forage component in all three systems was piata?-grass (Brachiaria brizantha cv. BRS Piata?). The experimental design was a randomized block in a sub-subplot design scheme with four replications. The presence of shade provided by the trees offered better conditions of animal comfort when compared with the condition of full sun. The ICLF-1 system, with higher tree density, provided better indicators for thermal comfort, THI, BGHI, and RTL when compared with the condition of full sun, while ICLF-2 was no different than ICLF-1 for BGHI.

English

This study aimed to analyze bioclimatic indexes: black globe temperature and humidity index (BGHI) and radiant thermal load (RTL) in Santa Ines sheep farms, with and without coverage to develop a fuzzy logical computational model to forecast variables analyzed experimentally. Ten Santa Ines sheep were placed in two cover paddocks, and one without cover. Data recorded were: air temperature schedules and black globe (°C), relative humidity (%) and wind speed (m s-1), and BGHI and RTL were calculated. Computational models were developed using fuzzy logic which had as input variables, air temperature (°C) relative humidity (%) for the output variables BGHI and RTL. Based on the experimental data, there were also certain relevance curves that conform more to the results for the model generation via Fuzzy logic. The Mandani inference method was used for the preparation of rules and defuzzification of the center of gravity method was applied. The results showed that in the critical periods, 12 to 14 h, coverage was insufficient to differentiate between stress environments. It was also found that the Fuzzy models compared with the experimental data were highly correlated with R² equal to 0.99, proving it is suitable for implementation in practice. Key words: Computational model, heat stress, shelter, simulation.

PHYSIOLOGICAL RESPONSES OF DAIRY COWS AS A FUNCTION OF ENVIRONMENT IN HOLDING PEN

ABSTRACT This research aimed to assess the climatization configuration in a holding pen for dairy cattle considering physiological responses of animals and thermal comfort indexes. Experimental design consisted of 16 cows in a Latin square design containing four groups of four animals (G1, G2, G3 and G4) and four periods (P1, P2, P3 and P4), in which four environments were used as treatments: EXT – external environment (control); SHA – shading with polypropylene mesh, 80% light interception; S+S – shading and water sprinkling; and S+S+V – shading, sprinkling and ventilation. Dry and wet bulb temperature, black globe temperature, wind speed and humidity were recorded during the climatization process, between October 13 and December 7. Subsequently, temperature-humidity index (THI), black globe temperature and humidity index (BGTHI), radiant heat load (RHL) and heat load index (HLI) were calculated. After climatization, respiratory rate (RR), surface temperature (ST), and rectal temperature (RT) were recorded. Animals submitted to EXT presented physiological responses that indicated heat stress. The best physiological response was found in S+S+V, which reduced RR by 58.6% when compared to the other environments.

CARACTERIZAÇÃO BIOCLIMÁTICA DE UM GALPÃO EXPERIMENTAL DE CRIAÇÃO DE FRANGOS DE CORTE NA REGIÃO DE DIAMANTINA-MG

Objetivou-se com este trabalho avaliar as condições bioclimáticas de um galpão experimental de frangos de corte da Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM), no campus JK, em Diamantina, MG. A avaliação foi feita com base na mensuração das variáveis ambientais de temperatura do ar, umidade relativa do ar, temperatura de globo negro e velocidade do ar no interior da instalação, em 42 dias de período experimental. Com os dados coletados foram calculados os índices de temperatura e umidade (ITU), o índice de temperatura de globo negro e umidade (ITGU), a carga térmica de radiação (CTR) e o índice de entalpia (Hº). O desempenho foi avaliado aos 42 dias de idade dos frangos, através dos parâmetros de peso vivo (PV), ganho de peso médio diário (GPMD), consumo de ração (CR), conversão alimentar (CA) e viabilidade criatória (VB). Verificou-se que, na maior parte do período experimental, a temperatura no interior do galpão esteve fora da zona de conforto térmico para as aves e a umidade relativa do ar encontrou-se acima dos limites recomendados, exceto no horário de 15:00 horas. O ITU esteve abaixo da zona de conforto até a segunda semana, indicando que as aves estiveram em estresse por frio neste período. O ITGU às 21:00 horas esteve fora do preconizado durante todo o período experimental. A CTR e o Hº também estiveram abaixo do preconizado em todo o período experimental, indicando pouca quantidade de calor na instalação onde os animais foram alojados. O desempenho dos frangos de corte mostrou-se inferior ao esperado. Neste sentido, recomenda-se realizar alterações no galpão como: reduzir as entradas de ar, diminuir o volume de ar a ser aquecido nas primeiras semanas de vida das aves e fornecer aquecimento suplementar ao nível de galpão, afim de, proporcionar o melhor conforto térmico e, consequentemente, maior desempenho produtivo dos frangos.

Thermoregulation of Girolando cows during summertime, in Pernambuco State, Brazil

This work was carried out to evaluate the physiological thermoregulation responses of Girolando-breed dairy cows kept in feedlot during summertime. A total of 15 animals were used, belonging to three genetic groups: 1/2, 5/8 and 3/4 Holstein-Gir (HG), with five cows from each genetic group, distributed in a completely randomized design, in subplots. The physiological parameters were sweat rate (SR), respiratory rate (RR), epidermis temperature (ET) and coat surface temperature (CST), and were evaluated once a week, during nine weeks, from December 2009 to February 2010, totaling 135 observations. Throughout the experimental period, climatic data were recorded using an automated weather station, and later used to calculate the different thermal comfort indexes: THI (temperature-humidity index), BGHI (black globe temperature and humidity index) and RTL (radiant thermal load). 1/2 HG animals showed the highest SR and lowest RR, ET and CST of all three genetic groups, while 3/4 HG cows had the lowest mean SR and highest ET and CST. 5/8 HG cows had intermediate values for SR, ET and CST. Mean RR values did not differ between 5/8 and 3/4 HG cows. It was concluded that animals from genetic groups 3/4 and 5/8 HG showed greater sensibility to heat stress than 1/2 HG cows.

Thermal comfort indices in individual shelters for dairy calves with different types of roofs

Among the building materials used in rural facilities, roofs are noteworthy for being largely responsible for thermal comfort, influencing the thermal balance within the shelter. This study aimed to evaluate the influence of roof on the Enthalpy (H), Thermal Load of Radiation (TLR), and Black Globe Temperature and Humidity Index (BGHI) in individual shelters for dairy calves. The design was completely randomized with three treatments: Z - zinc tile, AC - asbestos-cement tile and ACW - asbestos-cement tile painted white on the upper side. The averages were compared by the Scott Knott test at 1% probability. The results showed no statistical difference between treatments (P&lt;0.01) and the external environment for H. For TLR, there was statistical difference among all treatments, where ACW showed the lowest TLR, 489.28 W m-2, followed by AC with 506.72 W m-2 and Z with the highest TLR, 523.55 W m-2. For BGHI, the lowest values were observed for ACW (76.8) and AC (77.4), differing significantly from Z, which obtained the highest value (81.6). The tiles with white paint on the upper side promoted the lowest TLR and the lowest BGHI, favoring the thermal environment in the shelter.

Redução do nível de proteína bruta em rações para frangos de corte em ambiente de termoneutralidade

O experimento foi realizado para avaliar o efeito da redução do nível de proteína bruta (PB) da ração formulada de acordo com o conceito de proteína ideal e suplementada com aminoácidos industriais, sobre o desempenho e rendimento de cortes de frangos de corte machos de 22 a 42 dias de idade mantidos em ambiente termoneutro. Foram utilizados 280 frangos de corte machos "Cobb" com peso inicial de 856 ± 6,48 g, distribuídos em delineamento experimental inteiramente casualizado, com cinco tratamentos (21,6; 20,6; 19,6; 18,6 e 17,6% de PB), oito repetições de sete aves por unidade experimental. A temperatura no interior da sala foi mantida em 21,6 ± 0,7ºC, a umidade relativa em 74 ± 4,0% e a temperatura de globo negro em 22,5 ± 0,7ºC. O índice de temperatura de globo e umidade (ITGU) calculado para o período foi de 70 ± 0,9. Não houve efeito da redução dos níveis de PB sobre o ganho de peso e o consumo de ração, entretanto, a conversão alimentar foi influenciada pela redução dos níveis de PB sendo que as aves alimentadas com a ração que continha 22,0% de PB apresentaram o melhor resultado. A redução dos níveis de PB não influenciou o peso absoluto de carcaça e os pesos absoluto e relativo de peito, coxa e sobrecoxa. A redução do nível de PB da ração, de 21,6 para 17,6%, e formulada de acordo com o conceito de proteína ideal piora a conversão alimentar dos frangos de corte mantidos em ambiente termoneutro, não influenciando as demais variáveis estudadas.