Supplemental Figure 1. Effects of heat stress and dietary organic acid and pure botanical supplementation on (A) rectal and (B) skin temperatures, and (C) respiration rates of weaned Holstein calves (62 ± 2 d of age).

Bull and heifer calves were randomly assigned during the first week of life: thermoneutral conditions ( TN-Con; n = 12, 6 heifers and 6 bulls), heat-stress with no organic acids and pure botanicals (OA/PB) ( HS-Con; n = 12, 6 heifers and 6 bulls), thermoneutral conditions pair-fed to HS-Con ( TN-PF; n = 11, 6 heifers and 5 bulls), HS with low-dose OA/PB (75 mg/kg of body weight [BW]; AviPlus R; VetAgro S.p.A., Italy; HS-Low; n = 14, 8 heifers and 6 bulls), and HS with a high-dose of OA/PB (150 mg/kg of BW; AviPlus R; HS-High; n = 13, 7 heifers and 6 bulls).

Calves unsupplemented with OA/PB received a placebo containing matching dose of triglyceride. After weaning, calves (62 ± 2 d of age) were transported to a new facility where they were acclimated for 7 d in thermoneutrality (20 ± 1.7°C; 68 ± 0.4 % relative humidity; 63 ± 2 temperature-humidity index [THI]). Thereafter, calves were exposed to environmental conditions of TN (20 ± 1.3°C; 71 ± 0.3 % relative humidity; 67 ± 2 THI) or HS (32 ± 3.3°C; 41 ± 0.4 % relative humidity; 79 ± 2 THI).