Incubabilidade e qualidade de pintos de ovos de matrizes de frango de corte submetidos a estresse de temperatura

Abstract

This trial was carried out in order to evaluate the effect in broiler embryos of cold or heat stress on the hatching characteristics, and on the quality of the newborn chicks. Three hundred eggs obtained from 42-week-old broiler breeders were distributed in three incubators maintained at a temperature of 37.8C, relative air humidity of 60%, and mechanically turned on every two hour. At 16 days of incubation (D16), the embryos were submitted to heat (40C) or cold (32C) stress for 5 hours in two of the three machines. The non-stressed embryos of the third incubator were used as control. The data were analyzed in a complete randomized design with 3 treatments. The hatchability and chick s quality, evaluated by the number of neonatal and viable chicks, body weight at birth, and legs and navel qualities, were not different (P>0.05) among the control and temperature-stressed groups. However, results revealed that the eggs exposed to cold or heat stress showed a longer (P<0.05) incubation period – 506.5h and 504.2h, respectively -than those kept at normal temperature - 496.3h - as a consequence of a delay on internal (7 and 6h) and external piping (13 and 12h). It can be concluded that the 5-hour cold or heat stress at D16 is not enough to damage the hatchability or the quality of the chicks, but increase total incubation period, denoting that even a brief period of variation on the normal incubation temperature at a critical period of development is enough to determine stress in broiler embryos.