No abstract

Broiler productivity is dependent on a range of variables; among them, the rearing environment is a significant factor for proper well-being and productivity. Behavior indicates the bird’s initial response to an adverse environment and is capable of providing an indicator of well-being in real-time. The present study aims to identify and characterize the sequential pattern of broilers’ behavior when exposed to thermoneutral conditions (TNZ) and thermal stress (HS) by constant heat. The research was carried out in a climatic chamber with 18 broilers under thermoneutral conditions and heat stress for three consecutive days (at three different ages). The behavior database was first analyzed using one-way ANOVA, Tukey test by age, and Boxplot graphs, and then the sequence of the behaviors was evaluated using the generalized sequential pattern (GSP) algorithm. We were able to predict behavioral patterns at the different temperatures assessed from the behavioral sequences. Birds in HS were prostrate, identified by the shorter behavioral sequence, such as the {Lying down, Eating} pattern, unlike TNZ ({Lying down, Walking, Drinking, Walking, Lying down}), which indicates a tendency to increase behaviors (feeding and locomotor activities) that guarantee the better welfare of the birds. The sequence of behaviors ‘Lying down’ followed by ‘Lying laterally’ occurred only in HS, which represents a stressful thermal environment for the bird. Using the pattern mining sequences approach, we were able to identify temporal relationships between thermal stress and broiler behavior, confirming the need for further studies on the use of temporal behavior sequences in environmental controllers.

The need to comply with animal welfare has motivated the research for non-invasive methods that allow the evaluation of poultry and eggs to be painless while providing accurate measurements. In this scenario, bioelectrical impedance was tested as a minimally invasive tool for sexing day-old chicks of two different chicken strains and for evaluating the quality of eggs submitted to different days of storage relative to their hatchability. The resistance and phase angle measured allowed the differentiation between chicken strains, but not between sexes. Eggs stored for seven days showed higher resistance and lower phase angle those stored for only one day. Although the bioimpedance method seems to be a promising method to evaluate egg and chick quality, the results of the present study suggest that further studies are needed to validate its utilization, particularly in terms of electrode type and positioning, as well as for the determination of which electrodes and equipment are best suited for different evaluation purposes.

Broilers have better production rates when housed in thermal comfort conditions, outside of this zone the poultry need to maintain homeothermy. The heat production and thermal exchanges are related to body weight and available surface for heat exchange. The genetic evolution of broilers ensured high production with improvement in the feed conversion and reducing the slaughter time. The faster weight gain difficult sensible heat exchange, increasing the needs for climatization systems, in days with high temperatures. Changes in heat waves frequency and days with extreme temperatures are challenging situations for ventilation and evaporative cooling systems in broiler facilities. This review discusses heat exchanges of broilers and the challenges in maintaining the thermal comfort zone in poultry facilities, in a reality of increase of heat stress conditions. Keywords: welfare, heat production, body surface ESTRESSE POR CALOR EM FRANGOS DE CORTE E A NECESSIDADE DE SISTEMAS DE CLIMATIZAÇÃO RESUMOFrangos de corte apresentam melhores índices produtivos quando alojados em condições de conforto térmico, fora desta faixa necessitam manter a homeotermia. A produção de calor e as trocas térmicas estão relacionadas com o peso corporal da ave e a área de superfície disponível para as trocas térmicas. A evolução genética do frango de corte garantiu maior produção de carne com melhor conversão alimentar e menor tempo para o abate. A evolução do ganho de peso dificultou as trocas térmicas sensíveis aumentando a necessidade de sistemas de climatização, em dias com temperaturas elevadas. Estimativas para mudanças na frequência de ondas de calor e dias com temperaturas extremas são situações de desafio para os sistemas de ventilação e resfriamento evaporativo de aviários. Esta revisão discute as trocas térmicas de frangos de corte e os desafios em manter a zona de conforto térmico nas edificações em uma realidade de aumento de condições causadoras de estresse por calor.

The management of poultry feed is an important welfare promoter and the glycemic index a noninvasive evaluation. The aim was to evaluate the glycemic response of broiler breeders in restricted feeding system, and broilers receiving ad libitum feeding. Two experiments were carried out: I) 39-weekoldbroiler breeders, fed with three sources of fiber, in a completely randomized design in factorial scheme (3 fiber diets x 7 collection periods); and II) broilers, 42 days old, housed in different light systems, in a completely randomized design in factorial design (2 sexes x 2 lighting conditions x 13 collection periods). Blood glucose levels were measured at random collecting one blood drop from foot, with three replicates in each condition and treatment. In broiler breeder different fiber sources had no effect on glycemia, but the period affected circulating glucose levels, presenting a minimum of 184.3 mg dL-1 before feed and, a maximum of 242.5 mg dL-1 four hours after feeding. In broilers, there was a significant effect in glycemia for collection period and for sex, and interaction between lighting conditions and collection period. Further studies are needed to establish reference values to compare blood glucose levels in poultry.