Hatching phase influences thermal preference of broilers throughout rearing.

Here we aimed for the first time to analyse whether opposite hatching patterns associated or not to high incubation temperature from day 13 to hatching interferes with the thermal preference and response of broilers to heat stress throughout the rearing period. Fertile eggs from 56-week-old broiler breeders (Cobb-500®) were used in a completely randomized trial with a 2x2 factorial arrangement (Short-Long and Long-Short hatching patterns: short time interval between internal and external pipping followed by long time interval between external pipping and hatching, and long time interval between internal and external pipping followed by short time interval between external pipping and hatching, respectively; and control and high incubation temperatures: 37.5°C and 39°C from the 13rd day, respectively). Thermal manipulation from day 13 was chosen because it is known endocrine axes are already established at this time. At hatching, male chicks were reared in climatical chamber with 16 boxes, maintained at the temperature recommended for this strain, with 4 replicates of 18 chicks per treatment. Broilers with Long-Short hatching pattern and from eggs incubation at 37.5°C preferred the lowest ambient temperature at all analyzed ages, whereas broilers with Short-Long hatching pattern and from eggs incubated at 39°C preferred the highest temperatures from 21 days of age. Heat-exposed broilers showed increased respiratory frequency in all ages analyzed, which should have to contributed to maintainance of their rectal (body) temperature. The hatching patterns did not influence the feed intake, but broilers with Short-Long hatching pattern had better feed conversion, weight gain, and body weight. High incubation temperature reduced the feed consumption, as well as the weight gain and body weight by worsening the feed conversion. The results of this study reveal that hatching patterns associated or not to high incubation temperature influence the broiler thermal preference and heat response throughout the rearing period. Chicks with Long-Short and Short-Long hatching patterns should be reared separately, although this is not practical within a hatcher.

Torta de mamona destoxificada para alimentação de poedeiras comerciais / Detoxified castor cake feed for laying hens

Objetivou-se com este experimento avaliar o efeito da inclusão de torta de mamona destoxificada (TMD) na ração de poedeiras comerciais sobre o desempenho e a qualidade interna e externa dos ovos. Foram utilizadas 200 poedeiras comerciais de 40 a 50 semanas de idade, da linhagem Hy-Line W-36®, com 1543±34g de peso corporal, que foram distribuídas em um delineamento inteiramente casualizado com cinco tratamentos (0, 5, 10, 15 e 20% de torta de mamona destoxificada na ração) com cinco repetições de oito aves cada. Foram avaliados o consumo de ração, a produção, o peso e a massa de ovos e a conversão alimentar. A qualidade interna foi avaliada por meio da unidade de Haugh, percentual de albúmen e de gema. A qualidade da casca foi medida pela espessura, densidade específica e percentual de casca. As variáveis de desempenho foram afetadas pela inclusão da TMD com resposta linear negativa para o consumo de ração e quadrática para produção de ovos, peso do ovo, massa do ovo e conversão alimentar, com os melhores níveis de 10,5, 5,7, 9,2 e 10,3% respectivamente. Não houve efeito significativo da inclusão da TMD para as variáveis de qualidade interna e externa dos ovos. Concluiu-se que a TMD pode ser incluída na ração de poedeiras em até 5,7% para otimizar o desempenho e não alterar a qualidade interna e externa dos ovos.

This experiment aimed to evaluate the use of detoxified castor cake (DCC) in the diet of laying hens on performance and internal and external quality of eggs. A total of 200 laying hens with 40-50 weeks of age, of Hy-Line W-36® line, with 1543±34g body weight, were distributed in a completely randomized design with five treatments (0, 5, 10, 15 and 20% of DCC in diet) with five replicates of eight birds each. The feed intake, egg production, egg weight, egg mass and feed conversion were evaluated. The egg internal quality was evaluated by Haugh unit, percentage of albumen and yolk. The shell quality was evaluated by the thickness, density and specific percentage of eggshell. The performance variables were affected by the inclusion of DCC with a negative linear response to food intake and quadratic for egg production, egg weight, egg mass and feed conversion, with the best levels of 10.5, 5.7, 9.2 and 10.3% respectively. There was no significant effect of DCC inclusion for the variables of egg quality. It is conclude that the DCC can be included in hens diets up to 5.7% to optimize performance and do not alter the internal and external quality of the eggs.