O clima do cerrado pode causar estresse térmico em bovinos nelore no sistema de confinamento?

• Ano de defesa: 2019
• Autor(a) principal: Bomfim, Lorena Emily de Lemos Mota
• Orientador(a): Santos, Gladston Rafael de Arruda
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Programa de Pós-Graduação: Pós-Graduação em Zootecnia
• Palavras-chave em Português: Nelore (Bovino); Mudanças climáticas; Bovino de corte; Homeorrese; Índice de temperatura de globo negro e umidade; Índice de temperatura e umidade
• Palavras-chave em Inglês: Correlation; Homeorretic; Black globe temperature and humidity index; Temperature and humidity index
• Área do conhecimento CNPq: CIENCIAS AGRARIAS::ZOOTECNIA
• Link de acesso: http://ri.ufs.br/jspui/handle/riufs/11896

O estresse térmico é um dos fatores que podem levar a queda na produtividade do animal, influenciando no consumo, como também debilitando o metabolismo do animal, desviando sua energia, para dissipação do calor, em uma forma de tentar restabelecer o a termorregulação.The aim of this study was was to evaluate if the climate of the cerrado provides thermal stress in confined Nellore cattle. The experiment was carried out in the Beef Cattle Experimental Confinement of the Federal University of Goiás between July and October 2017, in the city of Goiânia-GO. Two hundred and twenty-four Nellore steers were used in the experiment, which were distributed in 28 collective bays in confinement system. The experiment had a duration of 105 days: 21 days for animal adaptation and 84 days of finishing period. The animals were submitted to the same nutritional management during the whole experimental period where a high inclusion of concentrate diet (10% of grass and 90% of concentrate feeding) based on corn, sorghum, soybean meal, urea and mineral supplement was offered. Four weighings were carried out, each of which was denominated period, so it was possible to evaluate the performance against the climatic changes that occurred, the performance data collected were, dry matter intake (DMI), avaraged daily gain (ADG), total weight gain (GPT) and feed gain (FG). Performance and climate data as average temperature (Tavg), maximum temperature (Tmax), minimum temperature (Tmin), thermal amplitude (TA), temperature humidity index (THI), black globe temperature and humidity index (BGTH) and relative humidity were collected. Three blood samples were collected between the periods, to quantify blood urea nitrogen (BUN) and non-esterified fatty acids (NEFA). The design was entirely at random, and the pen was considered the experimental unit. Pearson correlations were estimated for performance and climatic indexes. Performance and metabolic parameters between periods were evaluated by ANOVA and Tukey's test at 5% of significance with the software R. In the analysis of performance and temperature between the periods, the animals obtained a normal behavior for the conditions of feedlot, where the average temperature 22.98ºC, and the average values ITU 69,28 and ITGU 73,86, characterizing an environment of thermal comfort for animals. There was no significant correlation (p> 0,01) for total body weight gain (TBWG) and dry matter intake (DMI)) among the bioclimatic indexes. However, the final body weight (FBW), feed efficiency (FE) and dry matter intake / body weight (DMI / BW%) presented a significant correlation (p <0,01) among climatic indexes. There was no significant difference in the metabolic parameters (p> 0,01) among periods for the NEFA variable, but there was significant difference for the BUN variable (p <0,01), which one had 18,24 mg / dL, 24,15 mg / dL and 23,57 mg / dL for the first, second and third periods, respectively. It was concluded that the cerrado climate during the experimental period was not conducive to Nellore cattle under thermal stress confinement, without alterations in the metabolic profile for AGNE, but there was an increase in BUN metabolic concentrations during the periods, requiring more studies on this metabolite in confined Nelore.