Mean daily ambient temperatures in the barn were
26.8°C (range 22.0 to 31.3°C) at 0700 h, 30.0°C (range
23.3 to 35.0°C) at 1400 h, and 26.4°C (range 20.7 to
30.7°C) at 2200 h. The mean THI was 72.2 (range 66.1
to 77.7) at 0700 h, 84.3 (range 77.4 to 89.6) at 1400 h,
and 76.6 (range 69.1 to 82.3) at 2200 h (Figure 1).
There were no treatment effects (P > 0.05) on overall
respiration rates or rectal temperature; however, there
were significant effects based on time of day (P < 0.01)
for both body temperature and respiration rate (Table
2). Cows fed SFA had decreased rectal temperatures
at 1400 h (P < 0.05; Table 2) compared with controls.
Respiration rate was not different among treatments
during any time of the day (Table 2). There was a
tendency for increased respiration rate at 2200 h when
SFA was fed (P < 0.10; Table 2