The production system using cages is a highly polemical issue in Europe, because of the space restriction imposed to laying hens. It is considered that the cage system might compromise important comfort movements, welfare and egg quality. This study evaluated egg quality and welfare of two strains of hens housed in a conventional system (battery laying cages) or litter system with nest and perches, and submitted to heat stress or comfort conditions. Two groups of 20 birds (10 Hy-line W36 and 10 Hy-line Brown) were submitted to two environmental conditions (26°C and 60% RH or 35°C and 70% RH) and two housing systems (cages or litter) in the early production phase. Egg quality was analyzed based on egg weight, eggshell thickness, specific gravity, and Haugh units. Yolk and shell contamination by Salmonella sp was also assessed. A significant (p<0.05) reduction in quality parameters was observed in eggs produced by laying hens under heat stress, mainly in the birds housed in cages.

The matter of animal welfare has led to studies in order to evaluate alternative rearing systems for livestock in order to improve well-being. The semi-intensive system is an alternative method of rearing broilers in which the birds are kept in a poultry house and have free access to a pasture area during the day. It is known that ambient conditions may directly affect the behavior of birds reared in the semi-intensive system. Therefore, this research evaluated the behavior of four broiler strains reared under a semi-intensive system with a shaded area (provided by a black plastic screen - 50%) and the bioclimatic characteristics of this environment when compared with the non-shaded pasture. Thirty-five birds were reared in pens with 4.5 m² and 35 m² of pasture. Ambient variables were measured throughout the day to calculate the indexes of thermal comfort (BGHI and enthalpy). Data was analyzed in a 4 x 2 factorial (4 strains and 2 rearing environments) with 2 repetitions, in order to establish the rate of bird permanence in the pasture. There was an improvement in the ambient conditions of the shaded pasture in the hottest hours of the day (from 10:00 to 14:00 h), i.e., there was a reduction in the mean values of BGHI (approximately 26%) and enthalpy (36%). As a consequence, there was an increase in the rate of permanence in this environment if compared with the non-shaded pasture. Three out of four evaluated strains showed better adaptability to the semi-intensive rearing system.

Aves de quatro linhagens de galinhas para corte foram criadas no sistema semi-intensivo, em 16 boxes, sendo 4 boxes por linhagens, com 4,5 m² de área interna (abrigo) e 35 m² de área de pastejo, com o objetivo de analisar a adaptação dessas linhagens a esse sistema de criação, através de parâmetros ambientais e comportamentais. O período experimental desenvolveu-se entre 35 e 75 dias de idade, durante o qual foram coletados dados relativos à quantidade de aves presentes no pasto, temperatura e umidade relativa nos boxes e no pasto e porcentagem de sombra no pasto. Os parâmetros ambientais monitorados influenciaram o comportamento das aves. A análise bioclimática e a observação do comportamento permitiram diferenciar as linhagens estudadas no que diz respeito à adaptação das linhagens ao sistema semi-intensivo de criação. As aves das linhagens avaliadas mostraram-se adaptadas ao sistema semi-intensivo por demonstrar o comportamento esperado para esse sistema de criação.

Birds of four meat-type chicken lines were reared at the semi-intensive system with the objective of evaluate the adaptation to these breeding systems through environmental and behavioural parameters. The experimental period took place between 35 and 75 days of age during which it was collected data of number of broilers in the pasture, air temperature and relative humidity inside the boxes and in the pasture areas, and percentage of shadow in the pasture areas. Environmental factors influenced the behaviour of the evaluated lines. The bioclimatic analysis and the observation of the chicken behaviour allowed to discriminate the studied lines regarding to the adaptation to the semi-intensive breeding system. The broilers of the evaluated lines showed adaptation to the semi-intensive system, presenting the expected behaviour for this breeding system.

Aves de duas linhagens, sendo uma portadora do gene pescoço pelado (Na_) que determina redução no empenamento, e outra não portadora, com empenamento normal (nana), foram submetidas a estresse térmico gradativo (38, 40 e 42ºC), em câmara climática, nas idades de 28, 35 e 42 dias, com o intuito de se verificar a resistência ao estresse térmico. Foram verificadas diferenças significativas entre a temperatura retal média e a taxa respiratória média da linhagem de empenamento normal quando comparada com a linhagem de pescoço pelado, em todas as idades e períodos de estresse. Foram verificados valores mais altos das aves de empenamento normal, demonstrando a influência do conjunto temperatura de estresse térmico e idade. Pôde-se constatar que houve diferença significativa entre as linhagens para as médias de perda de peso apenas aos 35 dias de idade. Os resultados obtidos sugerem que a linhagem de pescoço pelado (Na_) possui maior resistência ao estresse térmico em relação à linhagem de empenamento normal (nana).

Birds of two lineages, a carrier of the Naked Neck gene (Na_) that determines reduction in the feathering and other non-carrier (normal feathering, nana), were submitted to thermal stress (38, 40 and 42ºC) in climatic chambers at 28, 35 and 42 days of age to verify the resistance to the thermal stress. Significant differences were verified among the mean rectal temperature of the normal feathered lineage when compared with the naked neck lineage, in all the ages and stress periods, with higher values in the normal feathered birds. The same result was found for mean respiratory rate. Significant difference was found for weight loss between the two lineages only at the age of 35 days. The results obtained suggest that the Naked Neck lineage possesses higher resistance to the thermal stress in relation to the normal feathered lineage.