Impacts of Dietary Humic Acid Supplementation on Growth Performance, Some Blood Metabolites and Carcass Traits of Broiler Chicks

This study was designed to evaluate the effect of graded levels of humic acid (HA) supplementation on broiler performance. Day-old broiler chicks (300) were randomly divided into 5 groups under completely randomized design (CRD). Five iso-caloric and iso-nitrogenous broiler starter and finisher diets (HA(0), HA(1), HA(2), HA(3) and HA(4)) containing 0, 0.75, 1.5, 2.25 and 3 g/kg HA, respectively, were formulated and were randomly allotted to each group. Results indicated that, during starter phase highest weight gain (WG) was observed in chicks fed HA(2) diet, but during finisher phase it was observed in birds fed HA(3) diet. Weight gain during whole experiment was also highest in broiler fed HA(3) diet. The best feed conversion ratio (FCR) was also observed in broiler fed HA(3) diets. There were no influences of humic acid on carcass weight, liver weight, heart weight, gut length, breast weight, thigh weight and abdominal fat weight. Blood glucose, urea, Ca, P, creatinine, red blood cells, white blood cells and haemoglobin were not affected by humic acid supplementation but blood cholesterol and low density lipoprotein (LDL) level were significantly reduced (P<0.05) in HA(3) and HA(4) diets. Therefore, it could be concluded that humic acid as an organic feed additive could improve growth performance of broiler chicks and reduce levels of total and low density lipoprotein cholesterol in the blood. The best level of HA to be recommended is 2.25 g/kg diet.