Effect of phloretin on growth performance, serum biochemical parameters and antioxidant profile in heat-stressed broilers

ABSTRACT The objective of this work was to evaluate the effect of phloretin on growth performance, serum biochemical parameters, antioxidant profile, glutathione ( GSH )-related enzymes, nuclear factor erythroid 2–related 2 ( Nrf2 ) and heat shock protein 70 ( HSP70 ) in heat-stressed broilers. A total of 240, 22-day-old Arbor Acres broilers were divided into 4 groups. The control group was housed at 23.0 ± 0.61°C and fed with basal diet, while the 3 heat-stressed groups (A, B, and C groups) were housed at 30.5 ± 0.69°C and fed with basal diet containing 0, 100, and 200 mg/kg phloretin, respectively. Serum was taken form 42-day-old broilers. Results showed that heat stress decreased ( P < 0.05) the final body weight ( FBW ), body weight gain ( BWG ), feed intake ( FI ), serum total protein ( TP ), triglyceride ( TG ), triiodothyronine (T3), thyroxine ( T4 ), GSH, catalase ( CAT ), and total antioxidant capacity ( T-AOC ) levels, but increased ( P < 0.05) the feed-to-gain ratio ( FGR ) and serum malondialdehyde ( MDA ) levels in broilers compared with that in the control group. Among the heat-stressed groups, supplementary 200 mg/kg phloretin increased ( P < 0.05) the FBW, BWG, FI, serum TP, TG, T4, GSH, CAT, and T-AOC levels, and decreased ( P < 0.05) the FGR and serum MDA in broilers. There were significant decreases ( P < 0.05) in the glutathione peroxidase ( GSH-Px ), γ-glutamylcysteine synthetase ( γ-GCS ), and Nrf2, but significant increases ( P < 0.05) in the HSP70 of the broiler serum after heat stress treatment. Among the heat-stressed groups, supplementary 200 mg/kg phloretin increased ( P < 0.05) the GSH-Px, γ-GCS, and Nrf2 levels, but decreased ( P < 0.05) the serum HSP70 level in the heat-stressed broilers. Under high temperature condition, FBW, BWG, FI, FGR, serum TP, TG, T4, MDA, GSH, CAT, T-AOC, GSH-Px, γ-GCS, Nrf2 and HSP70 were linearly affected by inclusion of phloretin. These results indicated that phloretin may improve growth performance, serum parameters, and antioxidant profiles through regulated GSH-related enzymes, Nrf2 and HSP70 in heat-stressed broilers.