Comparative study of forage toxic metals of conventional versus non-conventional pastures in relation to animal mineral nutrient allowance.

At present, the forage production is the foundation of beef cattle and sheep industries in graziery. This study was designed to assess the toxic metal composition of the conventional pastures and non-conventional pastures in consideration of mineral needs of ruminants. At all the surveyed sites, these mean soil metal concentrations were measured to be higher or lower than the referred threshold levels. Specifically, these concentrations of Co, Pb, and Cr were observed as much higher than the referred threshold levels of 0.01-0.06 mg/kg (Co), 0.05 mg/kg (Pb), and 0.02 mg/kg (Cr). On the contrary, the mean soil concentrations of Cd were observed to be relatively lower than the threshold levels of 0.50-10 mg/kg at all sites. The estimated mean concentrations of Co, Cd, Pb, and Cr in both conventional and non-conventional forage species were measured to be lower than the referred threshold levels. The supplementation of these metals for livestock grazing from pasture was unnecessary based on these findings. However, further research should be conducted for ecological safety and conservation of ruminant forages, so that both the conventional and non-conventional pastures are employed as livestock friendly consuming forages.