Effect of Dietary Mercury Concentrations on Growth Performance and Relative Organ Weight in Female Broiler Chickens

An experiment was conducted to investigate the effect of dietary mercury concentrations on growth performance and relative organ weight in female broiler chickens. A total of 400 2-d-old Ross 308 female broiler chicks were housed in 40 battery cages for a 5-wk feeding trial. Birds were randomly allotted to 1 of 5 dietary treatments with 8 replicated cages. Each replicate had 10 birds per replicate. Dietary mercury concentrations were set to 0, 50, 100, 250, or 500 mg/kg by adding mercury chloride (≥ 73.9%) at the expense of the celite. At the conclusion of the experiment, 1 bird per replicate with a body weight (BW) close to the replicate mean BW (i.e., 8 birds per treatment) were euthanised by CO₂ asphyxiation, then immediately dissected. The breast, liver, heart, kidney, spleen, lung, bursa of Fabricius, and small intestine were collected and weighed individually. Relative organ weight was expressed as a percentage of live BW. Results indicated that increasing mercury concentrations in diets decreased BW gain (linear and quadratic, P < 0.05) and feed intake (linear, P < 0.01) of female broiler chickens. Birds fed diets containing 500 mg/kg mercury showed less (P < 0.05) body weight gain and feed intake than those fed the control diets. However, there were no differences in feed efficiency and mortality among dietary treatments. The relative weight of the liver was increased (linear, P < 0.05) with increasing mercury concentrations in diets. There was a quadratic relationship (P < 0.01) between the relative weight of the small intestine and increasing mercury concentrations in diets. In conclusion, the concentrations of 500 mg/kg mercury in diets are toxic to female broiler chickens. The liver is likely the most sensitive organ to the toxic concentrations of mercury in diets for female broiler chickens.