Effect of dietary butyric acid on performance, intestinal morphology, microflora composition and intestinal recovery of heat-stressed broilers

• Butyric acid (BUT) improved performance of heat-stressed broilers.
• BUT ameliorated heat stress-induced damage in intestinal epithelia.
• BUT accelerated recovery of normal villus histological characteristics.
• BUT promoted growth of beneficial intestinal bacteria.

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 twenty-eight 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 diet+0.5 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 (P<0.05) 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 (P>0.05). 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 (P<0.05) 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.