The effect of vitamin C and formic acid on performance, carcass characteristics, immunity, and blood biochemical and hematological parameters of broilers under heat stress

The aim of this study was to compare the effects of dietary supplementation of vitamin C and formic acid on performance, carcass traits, immune organs, blood hematological and biological parameters of broiler chickens during heat stress. The experiment was conducted using a total of 120 day-old broiler chicks (Ross 308) by employing a completely randomized design with 3 treatments, 4 replicates and 10 birds in each replicate. Heat stress performed by setting room temperature on 34 ˚C for 8 hours per day from 29 to 42 days of age. The experimental treatments included: 1- basal diet (control), 2- basal diet + vitamin C (240 mg per kg of diet) and 3- basal diet + formic acid (0.5% of diet) in finisher diet. At the end of the trial, two birds from each replicate were slaughtered to measure the carcass traits. Blood samples were also taken from the wing vein of the chickens on day 42 to measure the biological and hematological parameters. Dietary supplementation of vitamin C and formic acid significantly improved daily body weight gain, daily feed intake and feed conversion ratio of the chickens (P<0.05). The supplemental vitamin C resulted in lower abdominal fat (P<0.05). Relative weights of spleen and bursa of Fabricius were significantly increased by dietary vitamin C (P<0.05). Dietary treatments increased total protein and declined total cholesterol and LDL-C levels, and vitamin C decreased glucose and increased HDL-C, T3 and T4 concentration of the blood (P<0.05). Vitamin C and formic acid significantly increased red blood cells (RBCs) and mean corpuscular haemoglobin concentration (MCHC) and decreased mean corpuscular volume (MCV) and heterophil to lymphocyte ratio (P<0.05). Dietary vitamin C and, to some extent, formic acid could eliminate the adverse effects of heat stress on broilers by having a positive effect on blood parameters and subsequently improved growth performance.