The study investigated the effect of butyric acid on heat-stressed broilers performance, intestinal histological
changes, beneficial intestinal bacteria counts and recovery responses. One hundred and twentyeight
Hubbard male broilers were equally distributed into 4 treatment groups, with 8 replicates per
treatment (4 birds each). At 21 d of age, birds were assigned into 2 dietary treatments and fed either a
control diet (CONTR) or the control dietþ0.5 g/kg butyric acid (BUT). Each dietary treatment was further
divided into 2 experimental groups; thermoneutral (TN) or heat stress (HS), each of which included one
group fed with CONTR and one fed with BUT. The TN-CONTR and TN-BUT birds were kept at 21 °C from d
21 to d 42. The HS-CONTR and HS-BUT birds were kept at 32 °C from d 21 to d 34 (heat stress period) and
returned back to 21 °C from d 35 to d 42 (recovery period). During the heat stress period, HS-CONTR
birds had reduced (Po0.05) body weight, daily gain, villus height, villus surface area and intestinal
weight compared with other treatment groups, while HS-BUT birds exhibited growth performance and
intestinal histological parameters similar to TN-CONTR birds (P40.05). During the recovery period,
butyric acid enhanced the recovery of body weight, villus height, villus surface area, epithelial cell area,
intestinal weight and viable counts of Lactobacillus and Bifidobacterium. Butyric acid had extra positive
effects in heat-stressed broilers as revealed by temperature diet interactions (Po0.05) detected in final
body weight, daily gain, feed conversion ratio, villus height, villus surface area, intestinal weight and
beneficial intestinal bacteria. It is concluded that dietary inclusion of butyric acid for heat-stressed
broilers can reduce intestinal epithelia damage and accelerate subsequent recovery of growth performance
and intestinal histological characteristics.