Effects of Heavy Metal Contamination on Blood Parameters, Egg Quality, and Histopathology of Layer Chickens influenced by Crude Oil Exploration

Introduction: Petrochemical pollution from oil spills, gas flaring, and effluents containing heavy metals is prevalent in the oil-producing regions of Delta State, Nigeria, posing systemic health risks to humans and animals. The present study assessed the effects of crude oil exploration on laying chickens across 21 poultry farms in seven zones of Delta State, Nigeria. Materials and methods: Blood, egg, and tissue samples (liver and kidney) from 105 layer chickens, comprising 15 chickens from each zone (Aniocha, Ijaw, Ika, Isoko, Itsekiri, Ukwani, and Urhobo), were analyzed for hematological, biochemical, and histological parameters. Results: The current findings revealed that packed cell volume (PCV) was significantly higher in Urhobo (45.56%) and Ijaw (39.22%) compared to the normal range of PCV. Hemoglobin levels ranged from 12.77 g/dL (Aniocha) to 15.46 g/dL (Ijaw), while white blood cell counts varied from 6.37 µL (Aniocha) to 8.40 µL (Urhobo). Red blood cell counts were significantly lower than the normal range from 4.01 µL (Isoko) to 5.10 µL (Urhobo). Serum albumin levels peaked in Urhobo (5.27 g/dL), whereas lower values were observed in Isoko and Ijaw farms. Alanine aminotransferase (ALT) was elevated in Urhobo (43.83 IU/L), Itsekiri (38.72 IU/L), and Ukwani (44.51 IU/L), exceeding physiological norms. Cadmium (Cd) concentrations exceeded permissible limits across all zones, with the highest level in Urhobo (21.032 ppm). The current findings highlighted the presence of environmental toxicity associated with oil-related pollution, signifying disruptions in blood chemistry, egg quality, and organ function in poultry. Conclusion: Elevated levels beyond physiological norms endanger animal health, compromise food safety, and threaten public health, highlighting the critical need for environmental monitoring and remediation in Delta State, Nigeria.