Survey of some heavy metals in forage of coastal rangelands of Bushehr province (Case study: Tangestan city)

Rangeland forage is the main source of feed for sheep and goats in many countries and the concentration of heavy metals in these plants is very important. Bushehr province is also affected by environmental pollution due to its proximity to the Persian Gulf, the occurrence of different wars and the existence of different oil and gas resources. The environment and rangelands, which feed on various livestock, are also exposed to these contaminants. Therefore, knowing the composition of the compounds and health of grassland forages will greatly help experts to better understand the health of meat and milk of animals that graze on these pastures.

Based on the rangeland area and the number of livestock in the coastal strip, two rangelands of Bashi and Rostami were selected and their grassland forage was randomly sampled. Plants were sampled at three grazing stages (first, middle and end of grazing season). Samples were dried in shade, then mixed and milled and sent to the laboratory.

The results showed that the average of lead, cobalt, cadmium and chromium were 0.30, 0.15, 0.017 and 3.73 mg/kg dry matter in total rangeland, respectively. Significant differences were observed in the amount of cobalt element in the two study areas and the amount of other elements was not significantly different. The amount of cadmium was significantly different in the various stages of grazing, with the highest concentration in the first stage of grazing.

In general, the concentrations of these elements in the fodder of coastal rangelands of Tangestan area of Bushehr province were at permissible level for grazing animals. No risk of shortage or poisoning for the animals was observed and hence no danger to human health.