The meta-analysis data were obtained from a survey of published articles over 15 years. The data were selected to classify the factors that impact broiler production and separated by influence aspects of animal production (thermal environment and other factors). The relevant data for each study were systematized, grouped and later tabulated and inserted into a database prepared in a spreadsheet. The variables used to analyze the thermal environment were temperature (comfort, high and low) and performance data (weight gain, feed intake, and feed conversion). The variables used for other features were ventilation (TER = tunnel + evaporative cooling, PP = positive pressure, NV = natural ventilation) and performance (feed conversion, live weight, mortality, and weight gain). The factors that may influence the production of broilers were tested by covariance analysis, Pearson correlation coefficient and divergence analysis, about the Cobb ® , Ross ® and Hubbard ® strains. The results showed that the factors that most influenced the performance of broilers were temperature, ventilation rate, and genetic strain.

RESUMOO estudo foi realizado com objetivo de avaliar os parâmetros fisiológicos de poedeiras alojadas em diferentes densidades de alojamento e períodos. Foram utilizadas 150 poedeiras Dekalb White com 20 semanas de idade alojadas em um galpão convencional com gaiolas metálicas com duas subdivisões de 50x45x40 cm 2 e distribuídas em três tratamentos: 8 aves por gaiola (562,5 cm 2 /ave); 10 aves por gaiola (450 cm 2 /ave) e 12 aves por gaiola (375 cm 2 /ave), com cinco repetições cada. Avaliaram-se parâmetros fisiológicos (frequência respiratória, temperatura cloacal e temperatura superficial) e condições ambientais (temperatura ambiente e umidade relativa) durante três ciclos de 28 dias. Adotou-se um delineamento inteiramente casualizado com arranjo fatorial 3x3 (três densidades de alojamento e três períodos). Os resultados demonstraram que a densidade de alojamento não prejudicou a frequência respiratória e a temperatura superficial, porém, a temperatura cloacal diferiu significativamente, sendo superior às 16 horas e a densidade de alojamento com 10 aves/gaiola permaneceu intermediário às outras densidades. Os parâmetros voltados à busca do conforto térmico evidenciaram que nos horários mais quentes do dia (até as 16:00 horas), independente da densidade, as aves apresentaram temperaturas maiores que na parte da manhã. Palavras-chave: produção de ovos, conforto térmico, condições ambientais WELFARE OF LAYING HENS IN DIFFERENT DENSITIES OF HOUSING ABSTRACTThe study was carried with objective to evaluate the physiologic parameters of bird laying housed on different housing density and period. Were used 150 Dekalb White bird laying with 20 weeks of age was housed on conventional aviary with metallic cages with two subdivision of 50x45x40 cm² and distribution on three treatments: 8 bird laying by cage (562,5 cm²/bird); 10 bird laying by cage (450 cm²/bird) and 12 bird laying by cage (375 cm²/bird), with five repetition each. Were evaluated physiologic parameters (respiratory frequency, cloacal temperature and superficial temperature) and ambience (environmental temperature and relative humidity) during three circles of 28 days. Was adopted a randomized design with factorial arrangement 3x3 (three housing density and three periods). The results demonstrate that the housing density not impaired the respiratory frequency and superficial temperature, however the cloacal temperature differed significantly, being higher at four p.m. nilsa

Ammonia (NH 3 ) emissions from broiler production can affect human and animal health and may cause acidification and eutrophication of the surrounding environment. This study aimed to estimate ammonia emissions from broiler litter in two systems of forced ventilation, the tunnel ventilation (TV) and the dark house (DH). The experiment was carried out on eight commercial broiler houses, and the age of the birds (day, d), pH and litter temperature were recorded.Broilers were reared on built-up wood shaving litter using an average flock density of 14 bird m -².Temperature and relative humidity inside the broiler houses were recorded in the morning during the grow-out period. A factorial experimental design was adopted, with two types of houses, four replicates and two flocks with two replicates each. A deterministic model was used to predict ammonia emissions using the litter pH and temperature, and the day of grow-out. . Model-predicted ammonia emissions provided comprehensible estimations and might be used in abatement strategies for NH 3 emission.

Light is an important environmental variable for the regulation and control of broiler behavior. Some light sources may also add heat to the rearing environment, and indirectly affect the heat exchange between the birds and the environment. This study aimed at investigation the surface temperature and behavioral response of broilers reared in an environment with monochromatic light emitted diode (LED). Broilers were reared inside commercial dark houses under two treatments: fluorescent or LED light sources. Bird surface temperature and behavior was monitoredfrom the first day of grow-out. The houses were virtually divided in four quadrants, and the variables were monitored in the geometric center of each quadrant. Surface temperature results were mapped, behavioral responses were divided as normal and abnormal, and their interaction with light source was tested. Broiler surface temperature in both houses presented lack of homogeneity, independently of the light source. No effect of the light source on any of the evaluated behavior was found in the present study. The long life and energy savings obtained with the LED light source suggest its use in broiler production.