ACCUMULATION OF SOME HEAVY METALS AND HISTOLOGICAL ASPECTS OF BODY TISSUES OF GROWING FRIESIAN CALVES FED POULTRY LITTER AND CORN SILAGE

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SUMMARY Eighteen male growing Friesian calves averaging 187±2.50 kg body weight and 9±0.19 months of age were used to study the effect of feeding rations containing different levels of poultry litter and corn silage on some heavy metals accumulation and histological aspects of body tissues. Calves were divided into three similar groups (6 in each) and were assigned randomly to the three experimental rations as follows: R1 (control): 65 % concentrate feed mixture + 15 % berseem hay + 20 % rice straw. R2: 12.5 % poultry litter + 12.5 % corn grains + 75 % corn silage. R3: 25 % poultry litter + 25 % corn grains + 50 % corn silage. The contents of copper (Cu), cadmium (Cd) and lead (Pb) were higher in poultry litter compared to the other tested feedstuffs. The concentrations of Cu, Cd and Pb in experimental rations and intake by growing calves increased with increasing the level of poultry litter and decreasing the level of corn silage. The concentrations of Cu, Cd and Pb in blood and seminal plasma, liver, kidneys, testes and muscles of growing Friesian calves significantly (P<0.05) increased when the level of poultry litter was increased and the level of corn silage was decreased. The concentrations of Cu, Cd and Pb in blood and seminal plasma, liver, kidneys, testes and muscles of growing Friesian calves fed R3 which contained 25% poultry litter were higher than the normal levels. Friesian calves fed R1 and R2 showed normal histological structure of body tissues. However, calves fed R3 showed severely damaged hepatocytes, more vacuolated and enlarged hepatocytes, lymphocytic infiltration between hepatocytes and necrotic area of hepatocytes of liver. Glomeruli lost their architecture and lumen of convoluted tubule besides the lymphocytic infiltration of kidneys. Degenerations and necrosis of the testes were observed while the semineferous tubles and their lumens were free from spermatozoa. It could be concluded that using poultry litter in the ration of growing calves fed corn silage at the level of 25% of DM basis led to an increase in the concentration of heavy metals in blood and seminal plasma and accumulation in body tissues causing abnormal histological aspects. So, poultry litter should not exceed 12.5% on DM basis of the ration.