Short cold exposures during incubation and postnatal cold temperature affect performance, breast meat quality, and welfare parameters in broiler chickens

Cold stimulations during egg incubation were reported to limit the occurrence of ascites in broilers subjected to cold temperature after 14 d of age. However, data are lacking on the impacts of such strategy in case of cold temperature conditions at start. This study aimed to evaluate the effects of incubation and posthatch cold challenge on performance, breast muscle integrity, and meat processing quality in broiler chickens. Ross 308 eggs were incubated under control temperature (I(0), 37.6°C) or subjected to 15°C during 30 min on day 18 and 19 of incubation (I(1)). Chicks from each group were reared in floor pens either at standard rearing temperature (T(0)), from 32°C at 0 d to 21°C at 21 d of age, or exposed to colder rearing temperature (T(1)), from 29°C at 0 to 21°C at 21 d of age. All birds were then kept at 21°C until slaughter (day 40), when body weights (BW), feed conversion ratio (FCR), breast muscle yield, meat processing quality, and the occurrences of meat defects, hock burns, and pododermatitis were recorded. No significant impact of incubation conditions on hatchability was observed. At day 40, BW was more under T(1) than under T(0) conditions, with T(0) females (but not males) presenting more BW after I(1) than after I(0) conditions. In the whole period, T(1) chickens presented lower FCR than T(0) chickens and higher breast meat yields at day 40. The occurrence of white striping was more in I(1)T(1) males than in all other groups, except for the I(0)T(1) males. Hock burns were more frequent in I(1)T(1) males than in all females and I(0)T(0) males, whereas the occurrence of pododermatitis was lower in T(0) males than in other groups. Despite some positive effects of I(1) incubation on growth after starting under low ambient temperature, this study reveals the limits of such strategy concerning chicken health and welfare, demonstrating that early thermal environment is a major component of the quality and sustainability of chicken meat production.