Behavioral changes in dairy calves raised in outdoor holding pens with alternative roofing / Alterações comportamentais de bezerras criadas em bezerreiros tropicais com cobertura alternativa

This study assessed the behavior of dairy calves raised in outdoor holding pens covered with different geosynthetics. Twenty crossbred (Girolando, Jersey and Holstein) dairy calves undergoing weaning were used, with an average initial live weight of 40.6 Kg. A completely randomized block design was used, with a 4 x 3 factorial scheme and 5 repetitions. The roofing materials were polyethylene mesh, drainage geocomposite, nonwoven geotextile and woven geotextile, representing the first factor, and assessment times (8 to 11 a.m., 11:15 a.m. to 2 p.m. and 2:15 to 6 p.m.) the second factor. Environmental variables were analyzed, and the following heat stress indices calculated: black globe-humidity index (BGHI) and equivalent temperature. The average BGHI and equivalent temperature were 79 and 26, respectively. Walking behavior differed between treatments (P<0.05) and was more frequent in the woven geotextile treatment. The most frequent behavior observed throughout the day was lying in the shade (53%), demonstrating the importance of providing artificial shading during this stage of life. When compared to polyethylene mesh, the drainage geocomposite and nonwoven geotextile were better suited to providing shade for dairy calves undergoing weaning in tropical regions.

O trabalho avaliou o comportamento de bezerras leiteiras, criadas em bezerreiros de modelo tropical, contendo diferentes geossintéticos como material de cobertura. Foram avaliadas 20 fêmeas Girolando, Jersey e Holandesa com peso inicial médio de 40,6 Kg durante a fase de aleitamento. O delineamento experimental foi de blocos casualizados completos, em arranjo fatorial 4 x 3 com 5 repetições. Os materiais de cobertura foram: malha de polietileno, geocomposto drenante, geotêxtil não-tecido e geotêxtil tecido foram o primeiro fator e os períodos do dia (08 às 11, 11:15 às 14 e 14:15 às 18 horas) foram o segundo fator. Foram avaliadas as variáveis ambientais e calculados os índices de conforto térmico: índice de temperatura do globo negro e umidade e índice de temperatura equivalente. As médias do índice de temperatura do globo negro e índice de temperatura equivalente foram 79 e 26, respectivamente. O comportamento andando diferiu entre tratamentos (P<0,05), sendo mais frequente no tratamento geotêxtil tecido. A frequência comportamental mais observada ao longo do dia foi deitada à sombra (53%) deixando evidente a importância da disponibilização de sombreamento artificial para essa fase de vida. Os materiais de cobertura geossintéticos Geodrenante e Geotêxtil não-tecido, comparados à malha de polietileno, foram os mais apropriados para a utilização como sombreamento em regiões de clima tropical para bezerras em fase de aleitamento.

Relationship between body weight and scrotal circumference in growing Pelibuey sheep raised under tropical conditions / Relação entre o peso corporal e a circunferência escrotal em ovinos Pelibuey em crescimento criados em condições tropicais

The body weight (BW) of an animal is a vital economic trait that might help in decision-making in the handling of animals. The objective of the present study was to develop equations for the prediction of BW in Pelibuey sheep using scrotal circumference (SC). The BW (23.40 ± 6.96 kg) and SC (20.25 ± 6.19 cm) have been recorded in 405 male Pelibuey at the Southeastern Center for Ovine Integration, Mexico. Linear, logarithmic, quadratic, exponential, cubic, and power regression models were used for data analysis. Pearson correlation (R), Coefficient of determination (R2), Adjusted coefficient of determination (Adj.R2) Root mean square error (RMSE), Akaike information criterion (AIC), and Bayesian information criterion (BIC) were used to select the best model. Power regression model showed the highest R (0.93), R2 (0.86), Adj.R2 (0.86) and lowest RMSE (0.02), AIC (-989.44) and BIC (-981.44). The current study suggests that SC might be used as the only predictor for BW of growing Pelibuey sheep raised under tropical conditions.

O peso corporal (PC) do animal é uma característica econômica importante, que pode auxiliar na tomada de decisões no manejo dos animais. O objetivo do presente estudo foi desenvolver equações para a predição do PC em ovinos Pelibuey por meio da circunferência escrotal (CE). O PC (23,40±6,96kg) e a CE (20,25±6,19cm) foram registrados em 405 ovinos machos da raça Pelibuey no Centro de Integração Ovina da Região Sudeste do México. Os modelos lineares, logarítmicos, quadráticos, exponenciais, cúbicos e de regressão de potência foram utilizados para a análise dos dados. A correlação de Pearson (R), o coeficiente de determinação (R2), o coeficiente de determinação ajustado (Adj.R2), o erro do quadrado médio (EQM), o critério de informação de Akaike (AIC) e o critério de informação bayesiano (BIC) foram usados para selecionar o melhor modelo. O modelo de regressão de potência apresentou maiores R (0,93), R2 (0,86), Adj.R2 (0,86) e menores EQM (0,02), AIC (-989,44) e BIC (-981,44). O estudo atual sugere que a CE pode ser usada como um único preditor para o PC de ovinos Pelibuey em crescimento criadas em condições tropicais.

Relationship between fish assemblage structure and predictors related to estuarine productivity in shallow habitats of a Neotropical estuary

The variability of fish assemblage structure with respect to seasonality in salinity and productivity remains to be elucidate to many Neotropical estuaries. In this study, we hypothesized that salinity gradient and a set of variables related to ecosystem productivity drive community parameters in the shallow-water fish assemblage of the north-south axis of the Paranaguá Estuarine Complex (Southern Brazilian coast). Samples were taken with beach seine monthly from May 2000 to April 2001. Supporting our hypothesis, richness and abundance increased with turbidity, warmer waters of the rainier summer seasons, which are more productive. This environmental setting favors reproduction, as well as juvenile recruitment and growth, whose intensities are highest in this period. Highest abundance was found in inner areas, which may be explained by greater food and habitat availability. Richness was higher in more saline waters, due to the proximity of the rich pool of marine fish species. We suggest that local human interventions (e.g., dredging) should be avoided during the rainy seasons that are critical for species life cycles. Salinization, low estuarine productivity, and warmer waters, which are expected with climate change and human impacts in the local watershed, could affect the integrity of the local fish assemblage.

A variabilidade da estrutura de assembleia de peixes em relação à sazonalidade da salinidade e produtividade ainda não foi elucidada para muitos estuários Neotropicais. Neste estudo, testamos a hipótese de que um conjunto de variáveis relacionadas à produtividade e ao gradiente de salinidade estuarino determina a estrutura da ictiofauna de habitats rasos do eixo norte-sul do Complexo Estuarino de Paranaguá (litoral sul brasileiro). As amostras foram obtidas mensalmente com "picaré", entre maio de 2000 e abril de 2001. Corroborando com a hipótese, riqueza e abundância aumentaram em águas mais turvas e quentes nas estações chuvosas e produtivas de verão, favorecendo reprodução, bem como recrutamento e crescimento juvenil que são mais intensos neste período. Abundância foi maior nas zonas internas, devido à maior oferta de alimento e habitat. Riqueza foi maior em águas mais salinas, devido à proximidade da ictiofauna marinha, que é mais rica. Sugerimos que intervenções humanas locais (como dragagem) sejam evitadas nas estações chuvosas que são críticas para o ciclo de vida das espécies. Salinização, redução da produtividade estuarina e águas mais quentes, esperadas com a mudança climática global e impactos humanos na bacia hidrográfica local, poderão afetar a integridade da ictiofauna local.

Effects of nitrogen and phosphorus availability on the early growth of two congeneric pairs of savanna and forest species / Efeitos da disponibilidade de nitrogênio e fósforo no crescimento inicial de dois pares congenéricos de espécies de savana e floresta

In the tropical region, savannas and seasonal forests, both highly diverse biomes, occur side by side, under the same climate. If so, that mosaic cannot be explained solely by climatic variables, but also by fire, water availability and soil status. Nutrient availability in the soil, especially nitrogen and phosphorus, has been postulated to explain the abrupt transitions between savannas and seasonal forests in tropical regions. Plants from these two biomes may present different nutritional strategies to cope with nitrogen and phosphorus limitation. We used two congeneric pairs of trees - each pair with a species from the savanna and another from the neighboring seasonal forest - to test whether savanna and forest species presented different nutritional strategies during their early development. We cultivated 56 individuals from each of these species in a hydroponics system with four treatments: (1) complete Hoagland solution, (2) Hoagland solution without nitrogen, (3) Hoagland solution without phosphorus, and (4) Hoagland solution without nitrogen and phosphorus. After 45 days, we harvested the plants and measured total biomass, root to shoot ratio, height, leaf area, and specific leaf area. Overall, savanna species were lighter, shorter, with smaller leaves, higher specific leaf areas, and higher root to shoot ratios when compared to the forest species. Nitrogen increased the performance of species from both biomes. Phosphorus improved the performance of the forest species and caused toxicity symptoms in the savanna species. Hence, savanna and forest species presented different demands and were partially distinct already as seedlings concerning their nutritional strategies.

Em regiões tropicais, savanas e florestas estacionais, biomas altamente diversos, ocorrem lado a lado, sob o mesmo clima. Sendo assim, esse mosaico não pode ser explicado somente por variáveis climáticas, devendo ser considerada a frequência e intensidade de incêndios, disponibilidade de água e status do solo. A disponibilidade de nutrientes no solo, especialmente nitrogênio e fósforo, tem sido postulada para explicar as transições abruptas entre savanas e florestas estacionais nos trópicos. Espécies vegetais desses dois biomas podem apresentar estratégias nutricionais diferentes para lidar com a limitação tanto de nitrogênio como de fósforo. Utilizamos dois pares de árvores congenéricas - cada par com uma espécie típica de savana e outra de floresta estacional vizinha - para testar se as espécies da savana e da floresta apresentaram estratégias nutricionais diferentes durante seu desenvolvimento inicial. Cultivamos 56 indivíduos de cada uma dessas espécies em um sistema hidropônico com quatro tratamentos: (1) solução Hoagland completa, (2) solução Hoagland sem nitrogênio, (3) solução Hoagland sem fósforo e (4) solução Hoagland sem nitrogênio e fósforo. Após 45 dias, colhemos as plantas e medimos a biomassa total, a relação raiz / parte aérea, altura, área foliar e área foliar específica. No geral, as espécies savânicas foram mais leves, menores em altura, área foliar e área foliar específica e apresentaram maiores razões entre biomassa radicular por biomassa aérea quando comparadas às espécies florestais. A oferta de nitrogênio aumentou o desempenho das espécies de ambos biomas. O fósforo melhorou o desempenho das espécies florestais e causou sintomas de toxicidade nas espécies savânicas. Concluímos que, já como mudas, espécies congenéricas de savana e floresta apresentaram demandas distintas e foram parcialmente diferentes em relação a suas estratégias nutricionais.

Effects of thermal environment on dairy cattle under a grazing system in the Western Amazon, Brazil / Efeitos do ambiente térmico em bovinos leiteiros em sistema de pastejo na Amazônia Ocidental, Brasil

This study aimed to evaluate the thermal conditions to which animals are exposed and their effect on the comfort/discomfort of dairy herds in a grazing system in the municipality of Sena Madureira, Acre State, Brazil. Eight farms and a total of 113 lactating crossbred cows were evaluated. Dry-bulb temperature (DBT, °C), relative humidity (RH, %), black globe temperature (BGT, °C), and wind speed (v, km h¹) were measured in January, February, and March (rainy season) to calculate temperature-humidity index (THI), black globe-humidity index (GTWBI), and radiant heat load (RHL). Moreover, the animals were measured for the physiological variables: rectal temperature (RT), heart rate (HR), and respiratory rate (RR). Significant differences (P<0.05) were observed for THI, GTWBI, and RHL. THI reached a mean value of 80 on farm G in January. Farm F had a GTWBI value of 79 in February. RHL reached the highest value (510 W m²). RT and HR showed no differences among the analyzed months. Thus, the environmental conditions in which dairy cows are housed at milking time rarely promoted thermal discomfort, with farm G being the most affected by THI.

Objetivou-se avaliar as condições térmicas a que os animais estão submetidos, seu efeito no conforto/desconforto de rebanhos leiteiros em sistema de pastejo, no município de Sena Madureira-Acre. Foram avaliadas oito propriedades e o total de 113 vacas mestiças em lactação. As medições ocorreram nos meses: janeiro, fevereiro e março (inverno amazônico), mensurando-se: temperatura do bulbo seco (TBS, °C), umidade relativa do ar (UR, %) e temperatura de globo negro (TGN, °C), velocidade do vento (v, km/h) para cálculos dos índices da temperatura e umidade (ITU), índice da temperatura de globo e umidade (ITGU) e carga térmica radiante (CTR), além da temperatura retal (TR), frequência cardíaca (FC), frequência respiratória (FR). Entre as propriedades analisadas, houve diferenças significativas (P<0,05) para ITU, ITGU e CTR. Destaca-se que o ITU na propriedade G, em janeiro, atingiu o valor médio de 80. A propriedade F, em fevereiro, teve valor de 79 para o ITGU. A CTR apresentou carga elevada (510 W.m³). A TR e a FC não apresentaram diferença entre os meses analisados. Concluiu-se que o ambiente ao qual as vacas leiteiras estão alojadas na hora da ordenha encontraram-se poucas vezes em situação de desconforto térmico, sendo a propriedade, a mais afetada pelo ITU.

Helminth and ectoparasitic faunas of the Harris's hawk, Parabuteo unicinctus (Accipitriformes: Accipitridae), in Chile: new data on host-parasite associations for Neotropical raptors / Helmintos e ectoparasitas do gavião-asa-de-telha (Accipitriformes: Parabuteo unicinctus) no Chile: novas associações parasita-hospedeiro para os rapinantes neotropicais

Abstract Birds of prey harbor a wide spectrum of various parasites, mostly with a heteroxenous life cycle. However, most reports on their parasites come from Europe. Although the Harris's hawk (Parabuteo unicinctus) is a widespread species in America, parasitological surveys on this hawk are mostly focused on coprological findings and ectoparasites, with poor attention paid to helminths. The aim of this study was to gather new and additional data on host-parasite associations for the Harris's hawk. Twenty-nine birds from central and southern Chile were necropsied. Further, nine birds from a rehabilitation center and 22 museum specimens were inspected for ectoparasites. Sixty-eight percent of birds hosted at least one parasite species. Four lice species, one mite species and eight helminth species (five nematodes, two platyhelminthes and one acanthocephalan) were recorded. Parasitic lice Colpocephalum nanum and Nosopon chanabense, and a nematode Cyathostoma (Hovorkonema) americana were recorded for the first time in raptors from the Neotropics. A feather mite, Pseudalloptinus sp., nematodes, Physaloptera alata and Microtetrameres sp., and a trematode Neodiplostomim travassosi, were recorded for the first time in Chile. The presence of diverse heteroxenous helminths reported here in the Harris's hawk could be explained by the generalist diet of this raptor.

Resumo As aves de rapina representam uma fonte importante de parasitas heteroxenos. Porém, a maioria dos relatos são da Europa. O gavião-asa-de-telha (Parabuteo unicinctus) é uma espécie amplamente distribuída no continente Americano, porém estudos parasitológicos nessas aves têm documentado achados coprológicos e ectoparasitas, com poucos relatos sobre endoparasitas como helmintos. Por essa razão, o objetivo deste estudo foi descrever novas associações parasita-hospedeiro para o gavião-asa-de-telha e rapinantes neotropicais. Vinte nove aves provenientes do centro e sul do Chile foram submetidas à necropsia. Por outro lado, nove aves de um centro de reabilitação e 22 espécimes de museu foram inspecionados em busca de ectoparasitas. Do total de aves, 68,3% foram identificadas como portadoras de pelo menos uma espécie de parasita. Quatro espécies de piolhos, um ácaro e oito helmintos (cinco nematoides, dois platelmintos e um acantocéfalo) foram registrados. Os piolhos Colpocephalum nanum, Nosopon chanabense e o nematóide Cyathostoma (Hovorkonema) americana são reportados pela primeira vez em rapinantes neotropicais. Colpocephalum nanum, N. chanabense, Pseudalloptinus sp., Physaloptera alata, Microtetrameres sp., C. (H.) americana e Neodiplostomim travassosi, são reportados pela primeira vez no Chile. A diversidade de helmintos heteróxenos, identificados neste trabalho, poderia ser explicada devido à dieta geralista do gavião-asa-de-telha.

Occurrence of Euscepes postfasciatus (Coleoptera: Curculionidae) in Ipomoea batatas in Diamantina, Minas Gerais, Brazil

Sweet potato, Ipomoea batatas (L.) Lam (Convolvulaceae), is an essential crop for food security in developing countries. Euscepes postfasciatus (Fairmaire) (Coleoptera: Curculionidae) is one of the main pests of I. batatas in tropical and subtropical regions. It feeds on the tuberous roots of I. batatas and induces perforations tunnel-shaped with excrement. The objective of this study was to register, for the first time, the occurrence of E. postfasciatus in I. batatas in the municipality of Diamantina, Minas Gerais, Brazil. Individuals of E. postfasciatus were found in the larval, pupal and adult stages feeding on the roots, in the genotypes, Brasilândia Branca, Rubisol, UFVJM01, UFVJM02, UFVJM03, UFVJM04, UFVJM08, UFVJM18, UFVJM91, UFVJM291 and UFVJM526 in a greenhouse at the Universidade Federal dos Vales do Jequitinhonha e Mucuri (UFVJM). Euscepes postfasciatus injuries formed superficial and deep galleries with the presence of excrement and unpleasant odor. The record of E. postfasciatus in I. batatas in the municipality of Diamantina is important to develop local strategies for integrated pest management of the crop in the region.(AU)

Growth and survival of the native oyster Crassostrea gasar cultured under different stocking densities in two grow-out systems in tropical climate / [Crescimento e sobrevivência da ostra nativa Crassostrea gasar cultivada em diferentes densidades em dois sistemas em clima tropical]

Survival and growth of the native oyster Crassostrea gasar along the juvenile and adult phases were evaluated in three different stocking densities [low (D), medium (2D) and high (3D)] and in two grow-out systems (fixed and floating system). The fixed system consisted of a rack made with PVC, fixed from the bottom with wood sticks. The floating system consisted of floating bags suspended by a rack made with PVC and maintained submerged from the seawater surface by eight floats. Survival and shell height of oysters cultured after 30, 60 and 90 days were registered in each phase and in each grow-out system. Results showed that the grow-out system did not affect survival and growth of C. gasar in the juvenile and adult phases. The tested densities affected the survival of oysters cultured over time in both phases but did not affect oyster growth. At times analyzed, it was observed positive growth in juvenile oysters grow after 90 days of culture. However, in the adult phase, no growth was observed after 90 days of culture. Oyster yield was higher in the density 3D, in both juvenile and adult phases. These findings contributed to the development of the oyster C. gasar culture.(AU)

A sobrevivência e o crescimento da ostra nativa Crassostrea gasar nas fases juvenil e adulta foram avaliados sob três diferentes densidades de estocagem [baixa (D), média (2D) e alta (3D)] e dois sistemas de engorda (fixo e flutuante). O sistema fixo consistiu em uma mesa de PVC, fixada na parte inferior com varas de madeira. O sistema flutuante consistiu em travesseiros flutuantes suspensos por uma mesa de PVC e mantidas submersas da superfície da água do mar por oito flutuadores. Registraram-se sobrevivência e altura da concha de ostras cultivadas após 30, 60 e 90 dias, em cada fase (juvenil e adulta) e em cada sistema (fixo e flutuante). Os resultados mostraram que o sistema de engorda não afetou a sobrevivência e o crescimento de C. gasar nas fases juvenil e adulta. As densidades testadas afetaram a sobrevivência das ostras ao longo do tempo, em ambas as fases, mas não afetaram o crescimento em altura. Nos tempos analisados, ostras juvenis apresentaram crescimento após 90 dias de cultivo. Porém, na fase adulta, não foi observado crescimento após 90 dias de cultivo. A produção de ostras, foi maior na densidade 3D, nas fases juvenil e adulta. Os presentes achados contribuíram para o desenvolvimento do cultivo da ostra C. gasar.(AU)

Physiological and hematological parameters of sheep reared in the tropics and subtropics / [Parâmetros fisiológicos e hematológicos de ovinos criados nos trópicos e nos subtrópicos]

This study aimed to determine the physiological and hematological parameters of sheep in Brazil. Therefore, 5,081 observations were used from previous experiments with animals from different Brazilian regions with the time of day, gender, breed, age, physiological characteristics, hematological and climatic variables. The animals were classified according to their stress level, and only data of non-stressed animals were used to calculate the reference values. Respiratory rate was the parameter that most differed from the normal range, with values ​​above the limits usually reported for the species, being higher in commercial wool sheep. For hematological variables, differences were observed between the present results and the previously reported values in the literature. A higher number of red blood cells (RBC), lower hemoglobin and mean corpuscular hemoglobin concentration (MCHC) were observed in young animals. A higher number of RBC and MCHC were noted in sheep crossed with local breeds. Considering that physiological and hematological parameters are indicators of the animal's pathological or physiological state, for a correct interpretation of the results, the use of reference values based on animals with similar racial characteristics and subjected to similar environmental conditions is recommended.(AU)

O objetivo deste estudo foi determinar parâmetros fisiológicos e hematológicos de ovinos no Brasil. Portanto, foram utilizadas 5.081 observações de experimentos anteriores com animais de diversas regiões do Brasil, com diferentes horário, sexo, raça, idade, características fisiológicas, variáveis ​​hematológicas e climáticas. Os animais foram classificados de acordo com o nível de estresse, e apenas os dados dos animais não estressados ​​foram utilizados para o cálculo dos valores de referência. A frequência respiratória foi o parâmetro que mais diferiu em relação à normalidade, com valores acima dos limites usualmente relatados para a espécie, sendo maior em ovinos de lã comercial. Para as variáveis ​​hematológicas, também foram verificadas diferenças entre os resultados observados e os valores previamente relatados na literatura. Maior número de hemácias, menor hemoglobina e concentração de hemoglobina corpuscular média (CHbCM) foram observados em animais jovens e maior número de hemácias e CHbCM em ovinos cruzados com raças locais. Considerando que os parâmetros fisiológicos e hematológicos são indicadores do estado patológico ou fisiológico do animal, para uma correta interpretação dos resultados recomenda-se a utilização de valores de referência baseados em animais com características raciais semelhantes e submetidos a condições ambientais também semelhantes.(AU)

Scrotal thermographic profile and seminal characteristics of Mangalarga Marchador stallions bred in the Atlantic Rainforest biome / [Perfil termográfico escrotal e características seminais de garanhões Mangalarga Marchador criados no bioma Mata Atlântica]

The objective of this study was to determine the scrotal thermographic profile and to verify the influence of temperature and humidity of the humid tropical climate on testicular temperature and seminal quality of Mangalarga Marchador stallions. The thermal profiles of the proximal, middle, and distal zones of the testicles and total surface temperature (TSTT) were recorded using an FLIR E60bx thermal imager. The average air temperature (°C) and relative humidity (%) were obtained 1, 5, 9, 33, and 66 days before semen collection and showed a mean value of 26.5±2.4 and 80.4±6.0 respectively. The scrotal surface temperature was close to 34°C and there was no variation with the age of the stallion, reproductive activity, and characteristics of the ejaculate (P>0.05). The only significant correlations obtained were between TSTT and minor defects (R = 0.41; P<0.05), between TSTT and total defects (R = 0.46; P<0.01), and between TSTT and percentage of morphologically normal sperm (R = -0.46; P<0.05). It was concluded that the Mangalarga Marchador stallions maintained the testicular temperature within favorable conditions for spermatogenesis, demonstrating the efficiency of testicular thermoregulation mechanisms in the Atlantic Forest biome.

O objetivo deste estudo foi determinar o perfil termográfico escrotal e verificar a influência da temperatura e da umidade do clima tropical úmido na temperatura testicular e na qualidade seminal de garanhões Mangalarga Marchador. Os perfis térmicos das zonas proximal, média e distal dos testículos e a temperatura da superfície total (TSTT) foram registrados usando-se um termovisor FLIR E60bx. A temperatura média do ar (° C) e a umidade relativa (%) foram obtidas um, cinco, nove, 33 e 66 dias antes da coleta de sêmen e apresentaram valor médio de 26,5 ± 2,4 e 80,4 ± 6,0, respectivamente. A temperatura da superfície escrotal foi próxima a 34°C, e não houve variação com a idade do garanhão, a atividade reprodutiva e as características do ejaculado (P>0,05). As únicas correlações significativas obtidas foram entre TSTT e defeitos menores (R=0,41; P<0,05), entre TSTT e defeitos totais (R=0,46; P<0,01), e entre TSTT e porcentagem de espermatozoides morfologicamente normais (R=-0,46; P<0,05). Concluiu-se que os garanhões Mangalarga Marchador mantiveram a temperatura testicular dentro de condições favoráveis para a espermatogênese, demonstrando a eficiência dos mecanismos de termorregulação testicular no bioma Mata Atlântica.

Processes that influence dissolved organic matter in the soil: a review

In tropical regions, climate conditions favor fast decomposition of soil organic matter (SOM), releasing into the soil organic composts in solid, liquid, and gaseous forms with variable compositions. Dissolved organic matter (DOM), a complex mixture of thousands of organic compounds, is only a small fraction of the decomposition products; however, it is highly mobile and reactive to the soil. Therefore, DOM play a key role in soil aggregation (formation of organometallic complexes), energy source for microorganisms, as well as C storage, cycling, and provision of plant-available nutrients. DOM multifunctionality to sustain soil functions and important ecosystem services have raised global scientific interest in studies on DOM fractions. However, previous studies were conducted predominantly under temperate soil conditions in natural ecosystems. Therefore, there is paucity of information on tropical soil conditions under agricultural systems, where DOM turnover is intensified by management practices. This review synthesized information in the literature to identify and discuss the main sources, transformations, and future of DOM in soils. We also discussed the importance of this fraction in C cycling and other soil properties and processes, emphasizing agricultural systems in tropical soils. Gaps and opportunities were identified to guide future studies on DOM in tropical soils.

Processes that influence dissolved organic matter in the soil: a review

In tropical regions, climate conditions favor fast decomposition of soil organic matter (SOM), releasing into the soil organic composts in solid, liquid, and gaseous forms with variable compositions. Dissolved organic matter (DOM), a complex mixture of thousands of organic compounds, is only a small fraction of the decomposition products; however, it is highly mobile and reactive to the soil. Therefore, DOM play a key role in soil aggregation (formation of organometallic complexes), energy source for microorganisms, as well as C storage, cycling, and provision of plant-available nutrients. DOM multifunctionality to sustain soil functions and important ecosystem services have raised global scientific interest in studies on DOM fractions. However, previous studies were conducted predominantly under temperate soil conditions in natural ecosystems. Therefore, there is paucity of information on tropical soil conditions under agricultural systems, where DOM turnover is intensified by management practices. This review synthesized information in the literature to identify and discuss the main sources, transformations, and future of DOM in soils. We also discussed the importance of this fraction in C cycling and other soil properties and processes, emphasizing agricultural systems in tropical soils. Gaps and opportunities were identified to guide future studies on DOM in tropical soils.(AU)

Índices de estresse térmico para touros jovens Nelore criados em ambiente tropical / Thermal stress indices in young Nellore bulls raised in tropical environments

Background: Thermal stress indices are important in predicting and choosing means for mitigating heat stress and defining critical environmental conditions for animal welfare and performance. The aim of this study was to determine theassociation between 16 thermal stress indices and thermophysiological variables in young Nellore bulls raised in a tropicalpasture to determine the most effective parameter of heat stress to assist in the management of the thermal environmentand animal welfare.Materials, Methods & Results: Seventy-eight young Nellore bulls (Bos taurus indicus), with a mean age of 10.5 monthsand mean body weight of 242.09 ± 32.17 kg at first collection, and 17.92 months and body weight 335.80 ± 39.02 kg atlast collection, were used. During the experimental period, rectal temperature (RT) and surface temperature at the forehead,scapula, and groin, from which the average surface temperature (AST) was calculated, were measured. The differencebetween the AST and air temperature (i.e., AST - AT) and between the RT and AST (i.e., RT - AST) defined the thermalgradient. For the evaluation of thermal environment, the dry bulb, wet bulb, and globe temperatures, and wind speed weremeasured. Relative humidity, mean radiant temperature, solar radiation, temperature humidity index (THI), black globaltemperature humidity index (BGHI), equivalent temperature index (ETI), environmental stress index (ESI), respiratory ratepredictor (PRR), heat load index (HLI), comprehensive climate index (CCI), and index of thermal stress for cows (ITSC)were calculated. The average and maximum air temperatures were above thermal comfort levels, while the average relativehumidity was within the ideal limit for cattle. The average globe temperature was higher than the air temperature. Solarradiation presented very high values and wind speeds were very low. RT indicated normothermia in the cattle, and ASTand thermal gradient (i.e., AST - AT) indicated thermal comfort...

Índices de estresse térmico para touros jovens Nelore criados em ambiente tropical / Thermal stress indices in young Nellore bulls raised in tropical environments

Background: Thermal stress indices are important in predicting and choosing means for mitigating heat stress and defining critical environmental conditions for animal welfare and performance. The aim of this study was to determine theassociation between 16 thermal stress indices and thermophysiological variables in young Nellore bulls raised in a tropicalpasture to determine the most effective parameter of heat stress to assist in the management of the thermal environmentand animal welfare.Materials, Methods & Results: Seventy-eight young Nellore bulls (Bos taurus indicus), with a mean age of 10.5 monthsand mean body weight of 242.09 ± 32.17 kg at first collection, and 17.92 months and body weight 335.80 ± 39.02 kg atlast collection, were used. During the experimental period, rectal temperature (RT) and surface temperature at the forehead,scapula, and groin, from which the average surface temperature (AST) was calculated, were measured. The differencebetween the AST and air temperature (i.e., AST - AT) and between the RT and AST (i.e., RT - AST) defined the thermalgradient. For the evaluation of thermal environment, the dry bulb, wet bulb, and globe temperatures, and wind speed weremeasured. Relative humidity, mean radiant temperature, solar radiation, temperature humidity index (THI), black globaltemperature humidity index (BGHI), equivalent temperature index (ETI), environmental stress index (ESI), respiratory ratepredictor (PRR), heat load index (HLI), comprehensive climate index (CCI), and index of thermal stress for cows (ITSC)were calculated. The average and maximum air temperatures were above thermal comfort levels, while the average relativehumidity was within the ideal limit for cattle. The average globe temperature was higher than the air temperature. Solarradiation presented very high values and wind speeds were very low. RT indicated normothermia in the cattle, and ASTand thermal gradient (i.e., AST - AT) indicated thermal comfort...(AU)

Key factors that influence for seasonal production of Guinea grass

Climate, soil and management are the main drives for growth and production of tropical pastures. Thus, a better understanding of the effects of these factors and their interactions under climate conditions is required to obtain effective management options. Here, we used data from two field trials to research on climate and management interactions on the production seasonality of Panicum maximum Jacq. Treatments included four sampling times (250, 500, 750, and 1000 °C accumulated) during eight regrowth period, under irrigated and rainfed conditions and, cuts were made to simulate grazing intensity. All treatments were arranged in a completely randomized block design with four replications. At each sampling time, basal tillers were sampled to observe meristematic differentiation and were linked with the respective daylength. Soil moisture was determined, and the water availability index (WAI) was calculated. The dry matter production (DMP) was taken and relative productivity was calculated. Soil moisture was the key seasonal drive in spring-summer and the WAI could be used to adjust the maximum production for that season. The major drive for DMP in fall was the daylength, which was found at 11.81 h. For all seasons, DMP correlated better with the residues in early regrowth phase (r = 0.82 and p < 0.0001) and with degree-days at final regrowth phase (r = 0.73 p < 0.01). Applying these critical values to management guidelines should make Guinea grass DMP more efficient on tropical farms.

Key factors that influence for seasonal production of Guinea grass

Climate, soil and management are the main drives for growth and production of tropical pastures. Thus, a better understanding of the effects of these factors and their interactions under climate conditions is required to obtain effective management options. Here, we used data from two field trials to research on climate and management interactions on the production seasonality of Panicum maximum Jacq. Treatments included four sampling times (250, 500, 750, and 1000 °C accumulated) during eight regrowth period, under irrigated and rainfed conditions and, cuts were made to simulate grazing intensity. All treatments were arranged in a completely randomized block design with four replications. At each sampling time, basal tillers were sampled to observe meristematic differentiation and were linked with the respective daylength. Soil moisture was determined, and the water availability index (WAI) was calculated. The dry matter production (DMP) was taken and relative productivity was calculated. Soil moisture was the key seasonal drive in spring-summer and the WAI could be used to adjust the maximum production for that season. The major drive for DMP in fall was the daylength, which was found at 11.81 h. For all seasons, DMP correlated better with the residues in early regrowth phase (r = 0.82 and p < 0.0001) and with degree-days at final regrowth phase (r = 0.73 p < 0.01). Applying these critical values to management guidelines should make Guinea grass DMP more efficient on tropical farms.(AU)

On the controlling of temperature: A proposal for a real-time controller in broiler houses

Environmental conditions in broiler houses, specifically temperature, are key factors that should be controlled to ensure appropriate environment for broiler rearing. In countries with tropical/subtropical climate, like Brazil, high temperatures produce heat stress to animals, affecting the production process. This research proposes a real-time model to control temperature inside broiler houses. The controller is a self-correcting model that makes real-time decisions on the ventilation system operation (exhaust fans) together with temperature prediction at the facility. The model involves partial differential equations (PDE) whose parameters are updated according to data registered in real-time. Some experiments were carried out at a pilot farm in the municipality of Jundiaí, São Paulo State, Brazil, for different periods during winter and summer. The results based on simulations in comparison with the current automatic ventilation system show that the model is consistent to keep temperature under control for an efficient production. The model achieved a bias of 0.6 °C on average in comparison with the ideal temperature, whereas the automatic controller measured a bias of 3.3 °C, respectively. Future lines suggest that this approach could be useful in many other situations that involve environmental control for livestock production.(AU)

Effect of frequency of protein-energetic supplementation on the performance and ingestive behavior of Nellore calves kept in a tropical pasture in the dry season / Frequência de suplementação proteico-energética sobre o desempenho e comportamento ingestivo de bezerros Nelore mantidos em pastagem tropical na estação seca

With the objective to evaluate different frequencies of supplementation on the performance and ingestive behavior of Nellore calves kept on Urochloa brizantha cv. Marandu pasture, 56 animals with initial average body weight (BW) of 174.5 kg were submitted to the following treatments: no supplement and 1x, 3x, and 7x supplementation per week. The supplement was provided in the amount of 3.5 g kg-1 of BW day-1. BW and evaluation of behavior were assessed every 28 days. The randomized block"s design with two repetitions was used. The analyses of variance were carried out by the GLM procedure in the SAS software, and the means were compared by the Tukeys test at 5% significance. The supplementation increased the average daily gain (ADG; P ? 0.05); however, it did not differ between frequencies (0.005, 0.190, 0.183, and 0.177 kg head-1 day for the no supplement treatment and 1x, 3x, and 7x per week, respectively). The animals in the no supplement treatment showed longer grazing time (P ? 0.05) compared to those receiving the supplement. However, results did not differ between frequencies (10.44, 8.57, 8.32, and 8.59 hours day-1 for no supplement treatments and 1x, 3x, and 7x per week, respectively). Thus, the frequency of supplementation can be reduced to once a week without reducing animal performance.(AU)

Com o objetivo de avaliar diferentes frequências de suplementação sobre o desempenho e comportamento ingestivo de bezerros Nelore mantidos em pasto de Urochloa brizantha cv. Marandu, 56 animais, com peso corporal (PC) inicial de 174,5 kg, foram submetidos aos seguintes tratamentos: sem suplementação, 1x, 3x e 7x por semana. O suplemento foi oferecido na quantidade de 3,5 g kg-1 de PC dia-1. A pesagem e a avaliação do comportamento foram feitas a cada 28 dias. O delineamento foi de blocos inteiramente casualizados com duas repetições. As análises de variância foram realizadas pelo procedimento GLM do SAS e as médias comparadas pelo teste de Tukey a 5% de significância. A suplementação aumentou o ganho médio diário (GMD; P ? 0,05), porém não diferiu entre as frequências (0,005, 0,190, 0,183 e 0,177 kg dia-1 para sem suplementação, suplementados 1x, 3x e 7x, respectivamente). Os animais do tratamento sem suplementação apresentaram maior tempo de pastejo (P ? 0,05) em relação aos animais suplementados, porém não diferiram entre as frequências (10,44, 8,57, 8,32 e 8,59 horas dia-1 para aqueles sem suplementação, 1x, 3x e 7x respectivamente). Assim a frequência de fornecimento pode ser reduzida para uma vez por semana, sem prejuízo ao desempenho animal.(AU)

Óleo de soja e sebo bovino na ração de poedeiras semipesadas criadas em regiões de clima quente / Soybean oil and beef tallow in the diet of semi-heavy laying hens reared in hot climate regions

The objective of this study was to evaluate the productive performance and physical quality of eggs from semi-heavy laying hens reared in hot climate regions and fed diets containing soybean oil or beef tallow. The experiment had a duration of 63 days divided into three cycles of 21 days each. A total of 160 semi-heavy Hisex Brown laying hens at 50 weeks of age and with an initial weight of 1.755 ± 0.172 kg were used. The birds were reared in a floor system and housed in boxes. A completely randomized design consisting of two treatments and five replicates was used, with 16 birds per experimental unit (box). Two experimental diets based on corn and soybean meal were formulated and soybean oil or beef tallow was added, corresponding to treatments 1 and 2, respectively. The following parameters were evaluated: egg production (%), feed intake (g/bird/day), egg mass (g/bird/day), feed conversion per egg mass (kg/kg), feed conversion per dozen eggs (kg/dozen), egg weight, percentage of yolk, egg white and shell (%), specific gravity (g/cm3), animal viability (%), and body weight variation (g). No differences (P>0.05) were observed in any of the parameters studied. The dietary inclusion of soybean oil or beef tallow does not influence the productive performance or egg quality of semi-heavy laying hens reared in hot climate regions.

O objetivo do estudo foi avaliar o desempenho produtivo e qualidade física dos ovos de poedeiras semipesadas criadas em regiões de clima quente, alimentadas com rações contendo óleo de soja ou sebo bovino. O período experimental teve duração de 63 dias, sendo dividido em três ciclos de 21 dias cada. Foram utilizadas 160 poedeiras semipesadas da linhagem Hisex Brown, com 50 semanas de idade e peso inicial de 1,755 ± 0,172 kg. As aves foram criadas em sistema de piso, sendo alojadas em boxes. O delineamento utilizado foi o inteiramente casualizado, composto por dois tratamentos e cinco repetições, com 16 aves por unidade experimental (boxe). Foram formuladas duas dietas experimentais a base de milho e farelo de soja, com a inclusão de óleo de soja e sebo bovino constituindo os tratamentos um e dois respectivamente. Os parâmetros avaliados foram: produção de ovos (%), consumo de ração (g/ave/dia), massa de ovos (g/ave/dia), conversão alimentar por massa de ovos (kg/kg), conversão alimentar por dúzia de ovos (kg/dúzia), peso dos ovos, porcentagem da gema, albúmen e casca (%), gravidade específica (g/cm3), viabilidade das aves (%) e variação do peso corporal (g). Não foram observadas diferenças (P>0,05) em nenhum dos parâmetros avaliados. O uso de óleo de soja ou sebo bovino na ração, não influencia o desempenho produtivo e qualidade dos ovos de poedeiras semipesadas, criadas em regiões de clima quente.

Óleo de soja e sebo bovino na ração de poedeiras semipesadas criadas em regiões de clima quente / Soybean oil and beef tallow in the diet of semi-heavy laying hens reared in hot climate regions

The objective of this study was to evaluate the productive performance and physical quality of eggs from semi-heavy laying hens reared in hot climate regions and fed diets containing soybean oil or beef tallow. The experiment had a duration of 63 days divided into three cycles of 21 days each. A total of 160 semi-heavy Hisex Brown laying hens at 50 weeks of age and with an initial weight of 1.755 ± 0.172 kg were used. The birds were reared in a floor system and housed in boxes. A completely randomized design consisting of two treatments and five replicates was used, with 16 birds per experimental unit (box). Two experimental diets based on corn and soybean meal were formulated and soybean oil or beef tallow was added, corresponding to treatments 1 and 2, respectively. The following parameters were evaluated: egg production (%), feed intake (g/bird/day), egg mass (g/bird/day), feed conversion per egg mass (kg/kg), feed conversion per dozen eggs (kg/dozen), egg weight, percentage of yolk, egg white and shell (%), specific gravity (g/cm3), animal viability (%), and body weight variation (g). No differences (P>0.05) were observed in any of the parameters studied. The dietary inclusion of soybean oil or beef tallow does not influence the productive performance or egg quality of semi-heavy laying hens reared in hot climate regions.(AU)

O objetivo do estudo foi avaliar o desempenho produtivo e qualidade física dos ovos de poedeiras semipesadas criadas em regiões de clima quente, alimentadas com rações contendo óleo de soja ou sebo bovino. O período experimental teve duração de 63 dias, sendo dividido em três ciclos de 21 dias cada. Foram utilizadas 160 poedeiras semipesadas da linhagem Hisex Brown, com 50 semanas de idade e peso inicial de 1,755 ± 0,172 kg. As aves foram criadas em sistema de piso, sendo alojadas em boxes. O delineamento utilizado foi o inteiramente casualizado, composto por dois tratamentos e cinco repetições, com 16 aves por unidade experimental (boxe). Foram formuladas duas dietas experimentais a base de milho e farelo de soja, com a inclusão de óleo de soja e sebo bovino constituindo os tratamentos um e dois respectivamente. Os parâmetros avaliados foram: produção de ovos (%), consumo de ração (g/ave/dia), massa de ovos (g/ave/dia), conversão alimentar por massa de ovos (kg/kg), conversão alimentar por dúzia de ovos (kg/dúzia), peso dos ovos, porcentagem da gema, albúmen e casca (%), gravidade específica (g/cm3), viabilidade das aves (%) e variação do peso corporal (g). Não foram observadas diferenças (P>0,05) em nenhum dos parâmetros avaliados. O uso de óleo de soja ou sebo bovino na ração, não influencia o desempenho produtivo e qualidade dos ovos de poedeiras semipesadas, criadas em regiões de clima quente. (AU)