Chromium propionate as a dietary strategy for heat stress mitigation in broilers

This study was conducted to evaluate the effects of chromium (Cr) levels and dilution rates in broiler diets under heat stress (HS) on performance, digestibility, immunity, carcass characteristics, and mineral retention. One-hundred and twenty-eight 1-day-old Arbor Acres broiler chickens (initial body weight of 37.98 ± 0.22 g) were used in this experiment for d 35. They were assigned to four treatment groups (eight replications, four birds each per cage): PC, birds fed a basal diet under thermoneutral temperature; NC, birds fed a basal diet and were exposed to cyclic HS at d 14 of age; CP2, PC with supplementing Cr 200 μg/kg as chromium propionate (Cr-Pro); CP4, PC with supplementing Cr 400 μg/kg as Cr-Pro. In this study, the NC exhibited decreased (<italic>p</italic> < 0.05) performance and nutrient digestibility compared to the PC, while showing increased (<italic>p</italic> < 0.05) mineral excretion and abdominal fat. Additionally, HS increased (<italic>p</italic> < 0.05) cortisol, norepinephrine, and immunoglobulin A and G levels, while decreasing (<italic>p</italic> < 0.05) glucose levels in serum. However, the CP4 showed higher (<italic>p</italic> < 0.05) body weight gain, crude protein digestibility, and retention of copper and chromium than the NC. Also, Cr-supplemented groups showed lower (<italic>p</italic> < 0.05) abdominal fat than the NC. In the serum profiles, Cr supplementation decreased serum norepinephrine levels under HS. Serum glucose levels were significantly higher (<italic>p</italic> < 0.05) in the CP4 compared to the NC. Serum IgG levels were significantly lower (<italic>p</italic> < 0.05) in the CP2 and CP4 compared to the NC. The CP4 showed a significant decrease (<italic>p</italic> < 0.05) in serum cortisol and H:L ratio compared to the NC. In conclusion, Cr-Pro is an additive that can mitigate the effects of HS, supplementation with 400 µg/kg Cr is suggested as a more effective alternative than 200 µg/kg.