Comparison of rectal and axillary temperatures of Isa brown and Harco Black layers fed different levels of dietary acetylsalicylic acid
This experiment was performed to compare the axillary and rectal temperature of two breeds of commercial layers: Harco Black (HB) and Isa Brown (IB) in their early stage of production. Four diets with different acetyl salicylic acid (ASA) levels of 0.00 % - the control diet (T1), 0.025 % (T2), 0.050 % (T3) and 0.075 % (T4) were fed to the birds throughout the eight weeks of the study. The result showed that the ambient temperatures were well above the birds’ thermo-neutral zone in the mornings (25.50oC), afternoons (31.75oC) and evenings (30.08oC) throughout the duration of the experiment. There were no breed differences (p>0.05) in the axillary temperature measured either in the mornings (MAXT), afternoons (AAXT) or evenings (EAXT) but the morning (MRT), afternoon (ART) and evening rectal temperature (ERT) differed between the HB and IB breed. ERT and EAXT were significantly different (p<0.05) among treatments. Layers fed dietary inclusion of 0.075 % ASA had the lowest ERT (41.54oC) and those fed the control diet had the highest ERT (41.72oC) and evening EAXT (40.85oC). The administration of ASA reduced the EAXT by 0.26oC and ERT by 0.18oC. Also, there was a decrease in the rectal temperature as the level of ASA in the diets increased. In conclusion, 0.075 % of ASA in layers diets could ameliorate the ill effects of heat stress on laying chickens through its anti-pyretic effects. Comparatively, the rectal temperature proved to be the more sensitive method of determining the core body temperature which fluctuates in consonance with the ambient temperature. Also, the Isa Brown breed could tolerate more heat stress than the Harco Black.
Keywords: Ambient temperature, Heat stress, Harco Black, Isa Brown, Layers, Rectal temperature