Reproductive response of synchronized and extensively grazed Blackbelly ewes during the summer in the tropics

The present experiment aimed to evaluate the reproductive response of Blackbelly ewes synchronized with low doses of eCG during the summer in a tropical climate. Sixty multiparous hair ewes were divided into three groups (20 ewes/group): control group (CG; 0 IU of eCG), treated group 1 (TG-1; 140 IU of eCG) and treated group 2 (TG-2; 300 IU of eCG). The study found that the three groups of ewes showed differences in their reproductive behavior (P < 0.01). Indeed, all the ewes in the TG-1 and TG-2 groups presented a higher response to estrus than the CG (P < 0.01). In the same way, TG1 and TG-2 had an onset to estrus in less time (P < 0.01). On the other hand, prolificacy was also higher in TG-1 and TG-2 (P < 0.05). Likewise, ewes from TG-1 and TG-2 had more lambs than those from CG (P < 0.05). On the other hand, the variables of fertility and gestation length were similar regardless of the group of ewes (P > 0.05). It´s concluded that the ewes treated with eCG presented good reproductive behavior, and the majority did so in the first 24 to 36 h after removing the intravaginal device.

Environmental and physiological measures in the neonatal period as indicators of growth and puberty of Holstein heifers / Medidas ambientais e fisiológicas no período neonatal como indicadores de crescimento e puberdade de novilhas Holstein

The present study assessed the influence of environmental variables at birth (birth season, temperature, relative humidity, THI - temperature and humidity index) and newborn serum protein level of 450 Holstein heifers on growth (body weight, and mortality rate) and reproductive performance (weight and age at puberty, age at first conception, and conception rate at first artificial insemination). The immune passive transfer was positively related to the weights at 30 and 60, with a trend at 90 days, which consequently affected weight at puberty, age at puberty, and age at conception. Therefore, it reinforces the importance of protocols with newborns that allow the assessment of the passive transfer of immunity. Calves born during the warmer months exhibited 4.2 and 12.28 kg less weight at weaning and puberty, respectively, compared to calves born during winter. Thus, calves born in an environment with higher THI showed changes in development, health, and reproductive efficiency in the short, medium, and long term. These findings reinforce the importance of adopting better colostrum management and welfare conditions, especially in warm season, to allow successful immune passive transfer and increase system efficiency.

O presente estudo teve como objetivo avaliar a influência das variáveis ambientais ao nascimento (estação de nascimento, temperatura, umidade relativa, ITU - índice de temperatura e umidade) e nível de proteína sérica no recém-nascido de 450 novilhas Holandesas sobre o crescimento (peso corporal e taxa de mortalidade) e o desempenho reprodutivo (peso e idade na puberdade, idade na primeira concepção e taxa de concepção na primeira inseminação artificial). A transferência de imunidade passiva foi positivamente relacionada ao peso corporal aos 30, 60 e 90 dias, o que consequentemente afetou o peso na puberdade, idade na puberdade e idade na concepção. Isto reforça a importância de protocolos com recém-nascidos que permitem a avaliação da transferência passiva de imunidade. Os bezerros nascidos durante os meses mais quentes apresentaram 4,2 e 12,28 kg de peso a menos no desmame e na puberdade, respectivamente, em comparação aos bezerros nascidos durante o inverno. Assim, os bezerros nascidos em um ambiente com maior THI apresentaram alterações no desenvolvimento, saúde e eficiência reprodutiva a curto, médio e longo prazo. Esses achados reforçam a importância de adotar melhores condições de manejo e bem-estar do colostro, especialmente nas estações mais quentes, para permitir a transferência de imunidade passiva bem sucedida e aumentar a eficiência do sistema.

Bioclimatic zoning and trend analysis applied to broilers / Zoneamento bioclimático e análise de tendência aplicados a frangos de corte

The objective of the present study was to establish the bioclimatic zoning by the temperature and humidity index (THI), considering a historical period and a future scenario, in order to represent the thermal environment for broiler breeding in the State of Minas Gerais. A historical series (1976 - 2014) of THI minimum, average and maximum calculated based on data from 48 conventional meteorological stations was used, belonging to the National Institute of Meteorology of the State of Minas Gerais. The analysis of the temporal series was based on the Mann-Kendall test and linear regression. A geostatistical analysis was also carried out to determine the comfort zoning of broilers as a function of the THI intervals. In this way, the THI spatial mapping methodologies and trend analysis for the prediction of a possible future climate scenario can help in the development of risk maps for monitoring thermal comfort of broilers, being indispensable in the planning of actions for the mitigation of the climatic change impacts on the productive chain of the State of Minas Gerais.(AU)

O objetivo do presente trabalho foi estabelecer o zoneamento bioclimático por meio do índice de temperatura e umidade (ITU), considerando-se um período histórico e um cenário futuro, de forma a representar o ambiente térmico para criação de frangos de corte no estado de Minas Gerais. Foi utilizada uma série histórica (1976 - 2014) de ITU mínimo, médio e máximo, que foram calculados com base em dados oriundos de 48 estações meteorológicas convencionais, pertencentes ao Instituto Nacional de Meteorologia do Estado de Minas Gerais. A análise da série temporal se baseou no teste de Mann-Kendall e na regressão linear. Procedeu-se, também, à análise geoestatística para determinação do zoneamento do conforto de frangos de corte segundo os intervalos de ITU. Dessa forma, as metodologias de mapeamento espacial do ITU e a análise de tendência para predição de um possível cenário climático futuro podem auxiliar no desenvolvimento de mapas de risco para o monitoramento do conforto térmico de frangos de corte, sendo indispensáveis no planejamento de ações para mitigação dos impactos das mudanças climáticas sobre a cadeia produtiva do estado de Minas Gerais.(AU)

Bioclimatic zoning and trend analysis applied to broilers / Zoneamento bioclimático e análise de tendência aplicados a frangos de corte

The objective of the present study was to establish the bioclimatic zoning by the temperature and humidity index (THI), considering a historical period and a future scenario, in order to represent the thermal environment for broiler breeding in the State of Minas Gerais. A historical series (1976 - 2014) of THI minimum, average and maximum calculated based on data from 48 conventional meteorological stations was used, belonging to the National Institute of Meteorology of the State of Minas Gerais. The analysis of the temporal series was based on the Mann-Kendall test and linear regression. A geostatistical analysis was also carried out to determine the comfort zoning of broilers as a function of the THI intervals. In this way, the THI spatial mapping methodologies and trend analysis for the prediction of a possible future climate scenario can help in the development of risk maps for monitoring thermal comfort of broilers, being indispensable in the planning of actions for the mitigation of the climatic change impacts on the productive chain of the State of Minas Gerais.(AU)

O objetivo do presente trabalho foi estabelecer o zoneamento bioclimático por meio do índice de temperatura e umidade (ITU), considerando-se um período histórico e um cenário futuro, de forma a representar o ambiente térmico para criação de frangos de corte no estado de Minas Gerais. Foi utilizada uma série histórica (1976 - 2014) de ITU mínimo, médio e máximo, que foram calculados com base em dados oriundos de 48 estações meteorológicas convencionais, pertencentes ao Instituto Nacional de Meteorologia do Estado de Minas Gerais. A análise da série temporal se baseou no teste de Mann-Kendall e na regressão linear. Procedeu-se, também, à análise geoestatística para determinação do zoneamento do conforto de frangos de corte segundo os intervalos de ITU. Dessa forma, as metodologias de mapeamento espacial do ITU e a análise de tendência para predição de um possível cenário climático futuro podem auxiliar no desenvolvimento de mapas de risco para o monitoramento do conforto térmico de frangos de corte, sendo indispensáveis no planejamento de ações para mitigação dos impactos das mudanças climáticas sobre a cadeia produtiva do estado de Minas Gerais.(AU)

Ethology, physiological, and ingestive responses of sheep subjected to different temperatures and salinity levels of water.

The objective of this study was to evaluate the physiological responses, ethology, and ingestive behavior of female Morada Nova sheep kept in a thermoneutral environment, after thermal stress and after consuming water with different levels of salinity. Thirty-six Morada Nova females with a mean age of 10.0 ± 2.0 months and a mean weight of 25.0 ± 3.0 kg were evaluated and distributed in a climatic chamber. The experimental design was completely randomized, with a factorial scheme of 2 (air temperature (AT)) × 3 (salinity levels (SLs)) and six replications. The sheep's physiological responses, ethology (day/night), and ingestive behavior were evaluated while they were subjected to ATs of 26.0 and 32.0 °C and SLs of 3.0, 6.0, and 9.0 dS/m. With elevation in AT, the animals experienced increased (P < 0.05) rectal temperatures (RTs), respiratory rates (RFs), and surface temperatures (STs) and exhibited reduced (P < 0.05) heart rates (HRs). When consuming water with an SL of 9.0 dS/m, a HR reduction (P < 0.05) was observed. Sleep behavior increased (P < 0.05) with the increase in SL during the day. Sleeping and drinking behaviors increased (P < 0.05), and the time of inactivity was reduced (P < 0.05) during the nocturnal period with increased SLs. With increased SLs, sheep consumed more water (P < 0.05) and reduced (P < 0.05) the number of regurgitated ruminal boluses per day (NRBD). Under the conditions of thermal stress (32.0 °C), sheep need to make physiological adjustments to maintain homeothermy. Water consumption of SLs up to 9.0 dS/m causes a higher state of dormancy in female Morada Nova sheep.

Temperature, thermal comfort, and animal ingestion behavior in a silvopastoral system / Temperatura, conforto térmico e comportamento ingestivo animal em sistema silvipastoril

Thermal discomfort is one of the main causes of production losses in animals fully exposed to solar radiation under extensive livestock farming. The inclusion of trees in this farming system is the most efficient strategy to decrease the temperature and increase animal productivity without the need to explore new areas. In this context, the objective of this study was to characterize the microclimate in a silvopastoral system (SPS), a refuge area, and an open pasture, and evaluate thermal comfort and the ingestive behavior of animals under shade. The study was conducted at the Agronomic Institute of Paraná (IAPAR), located in Ibiporã, Paraná state, Brazil, in three areas with distinct management systems: a SPS of Eucalyptus grandis with Tifton 85 (Cynodon spp.), a woodland of Leucena leucocephala that provided shade to cattle, and a pasture in full sun (PFS). Automatic meteorological stations were installed in the SPS (one station beside the tree lines and the other in an average distance perpendicular to the rows), one in the refuge area, and one in the PFS. The measured variables were air temperature and relative humidity. The mean temperatures of the shaded treatments were compared to those of the PFS using a t-test. The mean values of the temperature and humidity index (THI) were calculated for each season of the year. The animal ingestion behavior in the SPS was analyzed in three typical days in different seasons of the year. Significant differences were observed between shade treatments and full-sun pasture, with a temperature decrease ranging from 0.4 to 1.6 °C in the shaded systems. The comparison of animal thermal comfort between the study areas in different seasons of the year indicated that there were no significant differences in thermal comfort between the SPS and refuge area relative to the PFS, suggesting a need to monitor the animals body temperature to better estimate thermal comfort. The evaluation of the ingestive behavior evidenced the...(AU)

O desconforto térmico é uma das principais causas da queda produtiva da pecuária extensiva a pleno sol, sendo a inserção de árvores no sistema a alternativa mais eficiente para atenuar a temperatura e aumentar a produtividade sem a necessidade de explorar novas áreas. Nesse contexto, objetivou-se caracterizar o microclima em um sistema silvipastoril, uma área de refúgio e a pleno sol, além de estimar o conforto térmico e avaliar o comportamento ingestivo dos animais sob sombra. O estudo foi realizado na estação experimental do Instituto Agronômico do Paraná (IAPAR), localizada em Ibiporã-PR, em três áreas com manejos distintos: um sistema silvipastoril, um bosque que serve como refúgio dos animais e uma pastagem a pleno sol. Foram instaladas estações meteorológicas automáticas no sistema silvipastoril, uma sob a sombra e outra na distância média perpendicular aos renques, na área de refúgio e no pasto a pleno sol. As variáveis medidas foram temperatura do ar e umidade relativa do ar. As temperaturas médias dos tratamentos arborizados foram comparadas com as do pasto a pleno sol por meio do test t. Valores médios de Temperatura e Índice de Umidade (ITU) foram calculados para cada estação do ano. Analisou-se o comportamento ingestivo animal no sistema silvipastoril em três dias representativos de diferentes estações do ano. Constatou-se diferenças significativas entre os tratamentos sombreados e a pastagem a pleno sol, com redução de temperatura variando entre 0,4 a 1,6 °C nos sistemas sombreados. Ao comparar o conforto térmico animal para as estações do ano, não verificou-se diferenças entre o sistema silvipastoril e refúgio em relação ao pleno sol, sendo indicado monitorar a temperatura corporal animal para melhor estimar sua condição de conforto térmico. Entretanto, ao avaliar o comportamento ingestivo animal evidenciou-se a preferência dos animais por realizar suas atividades sob a sombra das árvores; o sistema silvipastoril propiciou mudanças no seu...(AU)

Temperature, thermal comfort, and animal ingestion behavior in a silvopastoral system / Temperatura, conforto térmico e comportamento ingestivo animal em sistema silvipastoril

Thermal discomfort is one of the main causes of production losses in animals fully exposed to solar radiation under extensive livestock farming. The inclusion of trees in this farming system is the most efficient strategy to decrease the temperature and increase animal productivity without the need to explore new areas. In this context, the objective of this study was to characterize the microclimate in a silvopastoral system (SPS), a refuge area, and an open pasture, and evaluate thermal comfort and the ingestive behavior of animals under shade. The study was conducted at the Agronomic Institute of Paraná (IAPAR), located in Ibiporã, Paraná state, Brazil, in three areas with distinct management systems: a SPS of Eucalyptus grandis with Tifton 85 (Cynodon spp.), a woodland of Leucena leucocephala that provided shade to cattle, and a pasture in full sun (PFS). Automatic meteorological stations were installed in the SPS (one station beside the tree lines and the other in an average distance perpendicular to the rows), one in the refuge area, and one in the PFS. The measured variables were air temperature and relative humidity. The mean temperatures of the shaded treatments were compared to those of the PFS using a t-test. The mean values of the temperature and humidity index (THI) were calculated for each season of the year. The animal ingestion behavior in the SPS was analyzed in three typical days in different seasons of the year. Significant differences were observed between shade treatments and full-sun pasture, with a temperature decrease ranging from 0.4 to 1.6 °C in the shaded systems. The comparison of animal thermal comfort between the study areas in different seasons of the year indicated that there were no significant differences in thermal comfort between the SPS and refuge area relative to the PFS, suggesting a need to monitor the animals’ body temperature to better estimate thermal comfort. The evaluation of the ingestive behavior evidenced the...

O desconforto térmico é uma das principais causas da queda produtiva da pecuária extensiva a pleno sol, sendo a inserção de árvores no sistema a alternativa mais eficiente para atenuar a temperatura e aumentar a produtividade sem a necessidade de explorar novas áreas. Nesse contexto, objetivou-se caracterizar o microclima em um sistema silvipastoril, uma área de refúgio e a pleno sol, além de estimar o conforto térmico e avaliar o comportamento ingestivo dos animais sob sombra. O estudo foi realizado na estação experimental do Instituto Agronômico do Paraná (IAPAR), localizada em Ibiporã-PR, em três áreas com manejos distintos: um sistema silvipastoril, um bosque que serve como refúgio dos animais e uma pastagem a pleno sol. Foram instaladas estações meteorológicas automáticas no sistema silvipastoril, uma sob a sombra e outra na distância média perpendicular aos renques, na área de refúgio e no pasto a pleno sol. As variáveis medidas foram temperatura do ar e umidade relativa do ar. As temperaturas médias dos tratamentos arborizados foram comparadas com as do pasto a pleno sol por meio do test t. Valores médios de Temperatura e Índice de Umidade (ITU) foram calculados para cada estação do ano. Analisou-se o comportamento ingestivo animal no sistema silvipastoril em três dias representativos de diferentes estações do ano. Constatou-se diferenças significativas entre os tratamentos sombreados e a pastagem a pleno sol, com redução de temperatura variando entre 0,4 a 1,6 °C nos sistemas sombreados. Ao comparar o conforto térmico animal para as estações do ano, não verificou-se diferenças entre o sistema silvipastoril e refúgio em relação ao pleno sol, sendo indicado monitorar a temperatura corporal animal para melhor estimar sua condição de conforto térmico. Entretanto, ao avaliar o comportamento ingestivo animal evidenciou-se a preferência dos animais por realizar suas atividades sob a sombra das árvores; o sistema silvipastoril propiciou mudanças no seu...

Genetic variation of the weaning weight of beef cattle as a function of accumulated heat stress.

The objective of this study was to identify the genetic variation in the weaning weight (WW) of beef cattle as a function of heat stress. The WWs were recorded at approximately 205 days of age in three Brazilian beef cattle populations: Nelore (93,616), Brangus (18,906) and Tropical Composite (62,679). In view of the cumulative nature of WW, the effect of heat stress was considered as the accumulation of temperature and humidity index units (ACTHI) from the animal's birth to weaning. A reaction norm model was used to estimate the (co)variance components of WW across the ACTHI scale. The accumulation of THI units from birth to weaning negatively affected the WW. The definition of accumulated THI units as an environmental descriptor permitted to identify important genetic variation in the WW as a function of heat stress. As evidence of genotype by environment interaction, substantial heterogeneity was observed in the (co)variance components for WW across the environmental gradient. In this respect, the best animals in less stressful environments are not necessarily the best animals in more stressful environments. Furthermore, the response to selection for WW is expected to be lower in more stressful environments.