The efficacy of a commercial additive containing carvacrol, anethole, limonene, and fructo-oligosaccharides on heat stress (HS) abatement in lactating dairy cows was evaluated. Control pen (n=92, DIM=91±53.1 d, average milk yield=37.0 kg) without feed additive (control) and phytogenic supplemented pen (n=112, DIM=122±46.8 d, average milk yield=36.1 kg) (PS) were fed a basal total mixed ration, while PS group received 15 g of additive into 2 equal parts top-dressed daily for 5 wks. Feed intake, milk production, rectal temperature, respiratory rate, fecal score, number of cows on feed bunk, and blood biochemistry were determined. The inclusion of PS increased feed intake (P<0.05) though it did not alter milk production. While the fecal score improved, the respiratory rate and concentration of thyroxine decreased decreased in PS-supplemented cows. Feeding PS increased the number of cows on bunk feed at 0330 and 0730. Overall, supplementation of PS helped alleviate some negative effects of HS though production performance was not affected. Manuscript profile