Cloacae and surface temperatures of hybrid converter tom turkeys exposed to 2 different temperature regimes during the first 12 weeks of growth

Abstract

Due to genetic selection, poultry of the 21st century reach a larger final body mass compared to earlier poultry when both strains are grown using the same conditions. Increased growth rates have resulted in increased heat production, which may have caused alterations to the bird's homeostatic processes and requirements. The objective of this project was to determine the thermal responses of Hybrid Converter Tom Turkeys when exposed to either the standard recommended rearing temperature or 4°C below the standard, on a weekly basis. An infrared camera was used to measure surface temperatures of the breast (Tbreast), drumstick (Tdrum), head (Thead), shank (Tshank) and wing (Twing) of 12 turkeys exposed individually over a 2 hour period once each week (wk) for 12 wks. A small thermal data logger (Tlogger) was also used to measure the surface temperature of the skin beneath the wing. Cloacal temperature (Tcore) was measured once before and after the test period. Temperatures of the feathered locations (Tbreast, Tdrum and Twing) decreased from wks 1 – 7 and then remained constant from wks 8 - 12 (P<0.05). In contrast, temperatures of the featherless locations (Thead, Tlogger and Tshank) increased from wks 1 - 3 and then decreased gradually from wks 3 - 12 as the exposure temperature decreased (P>0.05). The remaining featherless location (Tcore) was found to be lower during the first week before rising and remaining constant for the last 11 weeks. A decrease of 4°C caused a decrease in the temperatures of the feathered locations (P<0.05). The greatest calculated difference in temperature between the two treatment groups was seen with Tbreast, while Tdrum and Twing were less affected and had the same calculated difference. No difference in temperature was found between the treatment groups for Tcore (P>0.05). The remaining featherless locations were found to have different temperatures between the treatment groups during the first few wks of growth (P<0.05). Control temperatures were found to be higher in temperature than the treatment temperatures for all measurement locations where a difference in temperature occurred. Exposure temperature therefore, directly influences body surface temperatures to varying degrees, depending on the location's physical parameters and whether the location is feathered or featherless.