Elevated blood mercury and haematological response in free ranging chicken (Gallus Gallus domesticus) from gold mining areas in Zamfara State Nigeria

Abstract

Gold mining and other anthropometric activities in mining areas result in pollution. Mercury toxicosis is thus a common occurrence in chickens from gold mining areas (GMAs). The study was designed to evaluate and compare haematological response in chickens (Gallus Gallus domesticus) from Anka GMAs and Gusau Non‑gold mining areas (NGMAs) of Zamfara State, Nigeria. A total of sixty adult chickens were randomly selected in six locations (thirty each in GMAs and NGMAs). Blood mercury concentration was measured with atomic absorption spectrophotometer (AAS) with thermal decomposition. Haematological parameters which include packed cell volume (PCV), Red blood cell count (RBC), haemoglobin, heterophils, lymphocytes, total white blood cell count (TWBC), monocytes and heterophil/lymphocyte (H/L) ratio were measured using standard procedure. Both multivariate and univariate analysis were used to measure differences while correlation and regression were also used to analyse relationship between mercury and haematological parameters. Mean PCV 23.26%, RBC 2.661 × 10⁶/L, Haemoglobin 13.70 g/dL, TWBC 5.07 × 10 ⁹/L, Heterophils 2.00 × 10⁹/L and Lymphocytes 2.65 × 10⁹/L were significantly lower (p < 0.05) in chickens from GMAs when compared with 33.39%, 3.77 × 10 ⁶/L, 19.79 g/dL, 10.13 × 10⁹/L, 2.82 × 10⁹/L and 4.91 × 10⁹/L respectively from NGMAs. However, monocytes 0.44 × 10⁹/L and H/L Ratio 0.788 were significantly higher in chicken from GMAs when compared with 0.24 × 10⁹/L and 0.54 from NMGAs. Hameatological parameters are direct correlates of mercury concentration. A unit increase in monocytes significantly (p < 0.05) correspond to an increase in blood Hg level by 0.262 μg/mL. In conclusion, this research suggested that mining activities in GMAs exerts deleterious impacts on chicken haematological parameters. Result of this study will be of diagnostic significance in local chicken mercury toxicosis.