Respostas pós-eclosão após manipulação térmica na incubação

Abstract

This study assessed the effects of heat stress during incubation on performance, intestinal morphology, physiological variables and behaviour of broilers submitted or not to heat stress post-hatch. Fertile Cobb 500 eggs were placed in two artificial incubators at 37.7°C until 11 days of incubation. Afterwards, the temperature of one incubator was changed to 37.8°C (high temperature). At hatch, 48 birds per treatment were distributed into two climatic rooms under thermoneutral conditions; 3 boxes were used per incubation treatment in each room. At 21 days of age (d), the temperature of one room was adjusted to 33ºC (heat stress). A completely randomized design was used and birds were distributed according to a 2x2 factorial arrangement (two incubation temperatures, 37.7ºC and 38.7ºC; two rearing temperatures (25ºC and 33ºC). Data of performance, jejunum morphology and physiological parameters were submitted to ANOVA and different means were separated by Tukey test. Behaviour variables were analyzed using GENMODE and means compared by chi-square at 5% of probability. Thermal manipulation during incubation positively affected incubation parameters and one-day-old chicks and changed physiological parameters and jejunum morphology when birds were submitted to post-hatch heat stress. There was no effect of incubation temperature on behaviour or post-hatch performance.