Temperature acclimatisation - either during the incubation or the early growing period - has been suggested as an effective method to improve thermotolerance of broilers to cooler rearing temperatures, report M. Aksit from Adnan Menderes University in Turkey and co-authors there and at Ege University and at Virginia Polytechnic Institute and State University in the US.

In a paper in Journal of Applied Poultry Research, the scientists compared the response of broilers from younger and older breeder flocks to cooler rearing temperatures after temperature acclimatisation during incubation and early post-hatch.

Eggs were exposed to either a control incubation temperature (37.6°C) or a cooler temperature (36.6°C; IT-cool) for six hours (from 10:00 to 16:00h) daily from days 10 to 18 of incubation.

From days 22 to 42, chicks were reared at a control temperature (RT-cont), a cooler temperature (17 ± 2°C; RT-cool), or at a cooler temperature after acclimation of chicks to cooler temperatures by exposing them to 17 ± 2°C for six hours on day 5 post-hatch.

The IT-cool conditions reduced mortality and mortality due to ascites of older broilers reared under cooler temperatures from days 22 to 42.

Early age acclimatisation to cooler temperatures did not support thermotolerance of broilers, concluded the researchers.

Regardless of incubation temperature, the RT-cool broilers from younger breeders gained more weight but had poorer feed conversion than RT-cont.

Repeated cooler temperatures applied during incubation and early post-natal stage disturbed homeostasis and energy balance of broilers from older breeders.

Reference

^{Aksit M., S. Yalçin, P.B. Siegel, Ç. Yenisey, D. Özdemir and S. Özkan. 2013. Broilers respond to cooler ambient temperatures after temperature acclimation during incubation and early postnatal age. J. Appl. Poult. Res. 22(2):298-307. doi: 10.3382/japr.2012-00675}

August 2013