| dc.description.abstract | Nowadays there is an increasing concern in relation to human consumption of potentially toxic metal-contaminated animal products, namely, that normal cuts of meat, excluding liver and kidney. Therefore a series of trials were designed to evaluate tissue and organ of economical importance animal species, such as rabbit, responses to trace element (Cd, Pb, and Hg) levels that could actually exist in the feedstuffs in a farm. The daily rations included carrot, potato, or beetroot. The effects of toxic metal burden on growth, the digestibility, the changes of haematological and biochemical values as well as of pathophysiological processes were detected. Furthermore, for the investigation of the possible adverse effects of Ni burden, both a broiler chicken and rabbit model experiment were planned.
The carrot samples contained in DM 2.30 mg/kg Cd, 4.01 mg/kg Pb, and 30.00 mg/kg Hg, while the potato samples contained in DM 2.12 mg/kg Cd, 4.1 mg/kg Pb, and 3.44 mg/kg Hg and the beetroot samples contained in DM 4.72 mg/kg Cd, 3.03 mg/kg Pb, and 6.75 mg/kg Hg. Both the grower diet for broilers and the commercial pellet for rabbit were supplemented with 0, 50 or 500 mg/kg Ni.
The results of this study suggest that the adverse effect exerted by high concentrations of Cd, Pb and Hg can hardly be monitored by determining the classical zootechnical parameters (i.e. feed intake, body weight gain). The smaller body weight of rabbits fed carrot, potato or beetroot samples is probably due to the reduced dry matter and, consequently, the lower energy intake from these feedstuffs. Supplemental 500 mg/kg of Ni to the diet significantly (P<0.05) reduced weight gain, feed intake and worse FCE were observed in growing broiler cockerels.
After a 4-week ingestion of Cd, Pb or Hg, their concentrations in blood were significantly (P<0.001) elevated. RBC, HGB, and HCT are significantly (P<0.05) decreased while MCH and MCV are increased by Pb burden; macrocytic hyperchromic anaemia has developed in rabbits. The initial ZPP concentration was insignificantly (P>0.05) changed as a consequence of Pb-ingestion.
The increased activity of both AST and ALT and reduced activity of CHE are referring to the damage of the liver parenchyma. Both the reduced activity of GGT and the increased activity of ALP indicate toxicity of trace elements to the kidneys and/or liver. Due to the increased concentration of CREA as well, Cd, Pb and Hg burden of body could cause toxic effect to kidneys. The results of serum biochemistry have been confirmed by pathological focal fatty infiltration found in livers and by slight tubulonephrosis developed in kidneys of rabbits. Even 50 mg/kg of Ni damaged the liver parenchyma induces pathological focal fatty infiltration in broilers and rabbits.
The toxic elements (especially the Pb and Hg) reduced the activity of pancreatic amylase, trypsin and total protease, and lipase.
A large number of syncytial giant cells and degenerated cells indicating abnormal meiosis and reduced rate of spermatogenesis were observed among the spermatogenic cells in rabbit testes by Cd- or Pb-loading. The activity of ovaries could be reduced by supplementation of 500 mg/kg Ni.
The Cd burden of rabbits is highly reflected by kidneys, followed by liver. The highest mean concentrations of Pb, Hg and Ni were observed also in the kidneys. Hairs could also be good indicator of the Hg-burden but not for Cd or Pb. Concentration of toxic metals in kidneys of rabbit could exceed the their maximum permissible limit. Therefore consumption of organs like kidney and liver should be avoided if animal feed has been contaminated with toxic metals. | en |
