Effect of lead on health and productivity of layers

The effect of lead on productivity and health condition of Dominant hybrid layers in the 9th month of laying was observed for 45 d. Layers of the control group were fed complete mixed feed for layers. The 1(st) experimental group received feed supplemented with lead at a level of 1000 mg.kg(-1) mixed feed. The 2nd experimental group, in addition to this dose of lead received vitaminous and mineral mixture consisting of calcium carbonate, sodium hydrocarbonate, Foeniculi fructus, zinc sulphate, mangane-se sulphate, and vitamin C at 3% concentration. Lead addition caused a decrease in the egg weight, strength and thickness of egg shell, content of calcium, iron and vitamin E in blood as well as a decrease in solidity of the tibiae of the hens. The activity of alkaline phosphatase and alanine aminotransferase, content of phosphorus and copper and leukocyte count ill blood were enhanced by lead addition. This adverse effect of lead on metabolism of calcium and egg shell quality was confined by supplementation with the mentioned above vitaminous and mineral mixture. Lead addition reduced also the number of erythrocytes and content of haemoglobin. In one-day-old chicks there were significant changes in alanine aminotransferase activity. Lead at a dose of 1000 mg.kg(-1) feed caused neither clinical nor pathological changes in layers.