Study of the soil-plant (carrot)-animal cycle of nutritive and hazardous minerals in a rabbit model

Carrots were grown on soils polluted by heavy metal salts. Each particular microelement reached a high concentration [molybdenum (Mo) 39.00, cadmium ( Cd) 2.30, lead (Pb) 4.01, mercury (Hg) 30.00, and selenium (Se) 36.20 mg/kg dry matter] in the carrot. In a metabolic balance trial conducted with 15 male and 15 female New Zealand White rabbits, the control animals (n = 5) w ere fed nd libitum with concentrate as basal diet, while the other rabbits received the basal diet and carrots containing the particular microelement. Blood samples were taken to determine the activity of serum enzymes. To in vestigate the metabolism of Mo, Cd, Pb, Hg and Se, samples were taken from the heart, liver, lungs, kidneys, spleen, ovaries/testicles, entire digesti ve tract, adipose tissue, femur, hair, faeces and urine. Carrot had signifi cantly higher digestibility for all nutrients than the rabbit concentrate. Carrot samples of high Pb content had the lowest digestibility of crude pro tein. The microelements differed in their rate of accumulation in the organ s examined: Mo and Cd accumulated in the kidneys, Pb in the kidneys, liver, bones and lungs, Hg in the kidneys and liver, while Se in the liver, kidne ys and heart. The proportions of microelements eliminated from the body eit her via the faeces and urine (Mo 80.18% and Se 47.41%) or via the faeces (C d 37.86%, Pb 66.39%, Hg 64.65%) were determined. Pathohistological examinat ion revealed that the rate of spermatogenesis was reduced in the Mo, Cd, Pb and Hg groups compared to the control. Lead, Cd and Hg intake resulted in a considerable decrease in gamma-glutamyltransferase (GGT) and in an increa se of alkaline phosphatase (ALP) activity because of damages to the kidneys and bones. All experimental treatments decreased the activity of cholinest erase (CHE) because of lesions in the liver.