RESUMO
Two aviary sheds were used, the shed 1 (AECS) equipped with an adiabatic evaporative cooling system and the shed 2 (AECS + ESPB) equipped with an adiabatic evaporative cooling system together with an evaporative system of perforated bricks in the front and side of the shed. The temperature and the relative humidity of the air were assessed with automated devices (datalogger), together with the Environmental Thermal Index of Productivity for meat chicken (ETIPmc). Nine hundred and sixty male chickens from the Cobb strain were used, fed with isoproteic diets, except for the energy levels, which varied from 3,100 to 3,400 kcal. The use of the AECS was more efficient when associated to the ESPB. The AECS + ESPB provided a more comfortable and homogeneous environment, reflected on the productive parameters and favoring food conversion. Although the sheds exhibited moderately comfortable environments, according to the ETIPmc obtained, the AECS + ESPB showed a better balance of the environmental conditions between the sessions. The energy levels did not influence the variables analyzed, with the exception of the deposition of abdominal fat.
Foram utilizados dois galpões aviários, sendo o galpão 1 (SRAE) equipado com um sistema de resfriamento adiabático evaporativo e o galpão 2 (SRAE+SETV) equipado com um sistema de resfriamento adiabático evaporativo associado a um sistema evaporativo de tijolos vazados, instalado frontal e lateralmente a este galpão. Foram avaliadas a temperatura e a umidade relativa do ar por meio de equipamentos automáticos (datalogger), juntamente com o Índice Térmico Ambiental de Produtividade para frangos de corte (IAPfc). Utilizou-se 960 aves, machos, da linhagem Cobb, sendo as rações experimentais isoprotéicas, com exceção dos níveis energéticos, que foram de 3100, 3200, 3300 e 3400 kcal. A utilização do sistema de resfriamento adiabático evaporativo SRAE foi mais eficiente quando associado ao sistema evaporativo de tijolos vazados SETV. O SRAE+SETV proporcionou um ambiente mais confortável e homogêneo mostrando efeito sobre os parâmetros produtivos, favorecendo a conversão alimentar. Mesmo os galpões apresentando ambientes moderadamente confortáveis, segundo os valores do IAPfc obtidos, o SRAE+SETV mostrou melhor equilíbrio nas condições ambientais entre as sessões. Os níveis de energia influenciaram apenas a deposição da gordura abdominal.
RESUMO
Two aviary sheds were used, the shed 1 (AECS) equipped with an adiabatic evaporative cooling system and the shed 2 (AECS + ESPB) equipped with an adiabatic evaporative cooling system together with an evaporative system of perforated bricks in the front and side of the shed. The temperature and the relative humidity of the air were assessed with automated devices (datalogger), together with the Environmental Thermal Index of Productivity for meat chicken (ETIPmc). Nine hundred and sixty male chickens from the Cobb strain were used, fed with isoproteic diets, except for the energy levels, which varied from 3,100 to 3,400 kcal. The use of the AECS was more efficient when associated to the ESPB. The AECS + ESPB provided a more comfortable and homogeneous environment, reflected on the productive parameters and favoring food conversion. Although the sheds exhibited moderately comfortable environments, according to the ETIPmc obtained, the AECS + ESPB showed a better balance of the environmental conditions between the sessions. The energy levels did not influence the variables analyzed, with the exception of the deposition of abdominal fat.
Foram utilizados dois galpões aviários, sendo o galpão 1 (SRAE) equipado com um sistema de resfriamento adiabático evaporativo e o galpão 2 (SRAE+SETV) equipado com um sistema de resfriamento adiabático evaporativo associado a um sistema evaporativo de tijolos vazados, instalado frontal e lateralmente a este galpão. Foram avaliadas a temperatura e a umidade relativa do ar por meio de equipamentos automáticos (datalogger), juntamente com o Índice Térmico Ambiental de Produtividade para frangos de corte (IAPfc). Utilizou-se 960 aves, machos, da linhagem Cobb, sendo as rações experimentais isoprotéicas, com exceção dos níveis energéticos, que foram de 3100, 3200, 3300 e 3400 kcal. A utilização do sistema de resfriamento adiabático evaporativo SRAE foi mais eficiente quando associado ao sistema evaporativo de tijolos vazados SETV. O SRAE+SETV proporcionou um ambiente mais confortável e homogêneo mostrando efeito sobre os parâmetros produtivos, favorecendo a conversão alimentar. Mesmo os galpões apresentando ambientes moderadamente confortáveis, segundo os valores do IAPfc obtidos, o SRAE+SETV mostrou melhor equilíbrio nas condições ambientais entre as sessões. Os níveis de energia influenciaram apenas a deposição da gordura abdominal.
RESUMO
Assuming that selection in closed herds can promote reduction in additive genetic variance, multiple regression models were used to estimate this change in additive genetic (co)variance component, over the years when the selection was done. Weights at 550 days (W550) were studied using simulated data of herds submitted to 20 years of selection. (Co)variance components were estimated assuming that the weight at 550 days was a new trait every five years, by multiple-trait analyses involving four traits in the animal model. Three multiple regression equations were fittedRMI, RMM, RMFestimating thus the additive genetic (co)variance components for the 20 years of selection and eight years prior to the selection process. The initial years of each generation of selection were used as a covariate in the RMI. In the RMM, intermediate years were used, and the final years were considered in the RMF. The equations showed high coefficients of determination. However, there was no difference in the adjustment between the models. It was observed that the multiple regression models can be used in the estimation of genetic (co)variance components, when heteroscedasticity is assumed over time due to the selection process.
RESUMO
Assuming that selection in closed herds can promote reduction in additive genetic variance, multiple regression models were used to estimate this change in additive genetic (co)variance component, over the years when the selection was done. Weights at 550 days (W550) were studied using simulated data of herds submitted to 20 years of selection. (Co)variance components were estimated assuming that the weight at 550 days was a new trait every five years, by multiple-trait analyses involving four traits in the animal model. Three multiple regression equations were fittedRMI, RMM, RMFestimating thus the additive genetic (co)variance components for the 20 years of selection and eight years prior to the selection process. The initial years of each generation of selection were used as a covariate in the RMI. In the RMM, intermediate years were used, and the final years were considered in the RMF. The equations showed high coefficients of determination. However, there was no difference in the adjustment between the models. It was observed that the multiple regression models can be used in the estimation of genetic (co)variance components, when heteroscedasticity is assumed over time due to the selection process.