Influence of Temperature Manipulation during the Last 4 Days of Incubation on Hatching Results, Post-Hatching Performance and Adaptability to Warm Growing Conditions in Broiler Chickens

Two incubation and two growing trials were carried out. A total of 1000 (Trial I) and 1897 (Trial 2) eggs of the ROSS (308) strain were incubated from d 1 to 17 under normal conditions and from d 18 until hatch as follows: 37.2 to 37.4 degrees C (control), 38.2 to 38.4 degrees C for 24 h daily (chronic warm incubated) and 38.2 to 38.4 degrees C for 2 h daily (short term warm stimulated). In incubation Trial 2, the chickens were sorted by sex. Chick quality was analysed by the Pasgar score. In the 35 day growing Trial 1, a total of 240 one day old chickens and in Trial 2 a total of 120 male and 120 female chickens from all incubation groups were kept at 34 degrees C at d 1 and 2, and from d 3 up to the age of 35 days, at 32 degrees C. The results of the two incubation trials showed that chronic or short-term increase in incubation temperature at the end of incubation did not diminish hatchability and chick quality. The data indicates different effects of chronic and short-term warm incubation as well as warm growing conditions on the performance of female and male broiler chickens. Female chickens seem to be better adapted to warm growing conditions and show a higher tendency in performance parameters (feed intake, body weight gain, and body weight) during the final growing period. In male chickens exclusively chronic warm-incubation leads to a lowered daily feed intake in the final growing period which results in the lowest fattening weight of 1332 g per animal (control: 1476 g, short term warm incubated: 1482 g). A lower feed intake decreases the bodily heat production and can help to minimize heat stress. At slaughtering (Trial 2), the percentages of breast meat, liver, heart, stomach, spleen and fat showed no statistical difference between the groups or sexes.