Heavy metal poisoning and its impact on livestock health and production system

Abstract

Heavy metals are different from other toxic substances as they can be neither created nor destroyed. Anthropogenic activities are responsible for their redistribution into environment and exposure to man and animals. Biologically heavy metals are both beneficial and harmful. While a few heavy metals including copper, cobalt, iron, magnesium, manganese, selenium, and zinc are essential for vital physiological processes in trace amount, others like lead, cadmium and mercury are better known for their toxicities. Irrespective of their physiological role, all heavy metals when taken in excess than the tolerance limit are toxic. Animals are exposed to heavy metals via contaminated feed, fodder, forage and water mainly due to anthropogenic environmental pollution. Soils and water-bodies in certain geographic regions were found to carry excess concentration of heavy metals, which can be a natural source of poisoning in animals. Once consumed, heavy metals persist in the body for considerable time, and depending on the extent of exposure they induce acute or chronic; clinical or subclinical or subtle toxicities. Acute heavy metal poisoning is associated with typical clinical symptoms culminating into the death of an individual animal or a group of animals with similar necropsy findings. Chronic toxicities are characterized by detrition in general condition and loss in production. Presence of heavy metals above critical level in edible animal products is a cause of public health concern. Early diagnosis and specific antidote and management can effectively reduce the adverse impact of heavy metals on livestock health and production. Highlights:  Heavy metal poisoning is one of the major non-infectious causes of adverse impact on animal health and production.  Range of anthropogenic activities cause redistribution and elevated concentrations of heavy metals in the environment.  Heavy metals bioaccumulate and persist in the body for considerable time, and can induce acute or chronic; clinical or subclinical or subtle toxicity.  Presence of heavy metals above critical level in edible animal products is a cause of public health concern.  Timely diagnosis, specific antidote therapy and management constitute the mainstay for early recovery.