Effects of Early Heat Conditioning on Performance in Broilers exposed to Heat Stress
2014
Yoon, H.S., Gyeongsang National University, Jinju, Republic of Korea | Hwangbo, J., RDA, Cheonan, Republic of Korea | Yang, Y.R., Gyeongsang National University, Jinju, Republic of Korea | Kim, J.M., Gyeongsang National University, Jinju, Republic of Korea | Kim, Y.H., Gyeongsang National University, Jinju, Republic of Korea | Park, B.S., Gyeongsang National University, Jinju, Republic of Korea | Choi, Y.H., Gyeongsang National University, Jinju, Republic of Korea
Heat manipulation at early age has been known to help chickens cope with heat stress later in life. The present study was conducted to determine the effects of early heat conditioning at 5 days of age on performance in broilers when re-exposed to heat stress later in life. Day-old, 256 Arbor Acre boiler chicks were housed in two identical rooms where all broilers were exposed to a 23-h light: 1-h dark cycle throughout the study and provided with feed and water ad libitum. At the age of 5 days, one group was exposed to 37℃ for 24 hours and then returned to the temperature at which control birds were maintained (early heat condition group) while the other was maintained without heat modulation (Control). On 21 days, broilers were regrouped into 4 groups (CON+CON: control+control; CON+HS: control+heat stress; HC+CON: heat conditioning+control; HC+HS: heat conditioning+heat stress), and given 7 days for adaptation. On 28 days, birds in one room were exposed to heat stress (21℃-31℃) for 3 days whereas those in the other were at room temperature. Heat stress resulted in decreased feed intake, water intake, and body weight gain (P0.05), but increased rectal temperature and mortality (P0.05). No beneficial effects of heat conditioning were detected when broilers were exposed to heat stress again at later in life. The present results were discussed together with other studies regarding possible differences in methods such as ages of breeders and strains, which may have resulted in the failure of heat conditioning to help broilers resist heat stress.
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