The effect of adding cadmium and lead alone or in combination to the diet of pigs on their growth, carcase composition and reproduction

Limits for cadmium and lead concentrations in food animal products have been established independently, whereas these two toxic metals often co-exist in polluted regions. Weaned pigs (60) were allocated to ten treatments: control; low (0.5 mg kg(-1)), medium (1 mg kg(-1)) or high cadmium (2.5 mg kg(-1)) in feed; low (5 mg kg(-1)) medium (10 mg kg(-1)) or high (25 mg kg(-1)) lead in feed; and low, medium and high cadmium plus lead in feed. Growth rates and concentrations of cadmium and lead in body tissues (kidney, liver, spleen, lungs, heart, testicle, ribs, hair and teeth) were measured after 137 days. There was a similar reduction in weight gain for pigs in the cadmium and lead treatments, compared with the control, and a greater reduction for the pigs in the cadmium plus lead treatments. The reduction increased with the level of metal included. There was an increase in cadmium concentration of all tissues and blood with increasing feed cadmium concentration, which was usually less when lead was also included in the feed. There was also an increase in tissue lead concentration with increasing dietary lead, and this was in most cases increased when cadmium was also included in the feed. The most sensitive tissues for cadmium and lead exposure were the kidney, liver, hair and teeth, and regression equations were developed for the accumulation rates in these tissues. Tissue and blood cadmium concentrations increased gradually with increasing dietary lead, whereas tissue lead concentration was not sensitive to dietary cadmium, except in the ribs and heart. In a second experiment, 10 sows were allocated to a control diet or the same diet but with a supplement of cadmium and lead. The birth weight of piglets was decreased by the supplement and their mortality increased. Lead accumulated most in the ovary and oviduct of the sows, and there were increases in the lead and, to a lesser extent, cadmium concentrations of tissues of the piglets from these sows. (C) 2003 Society of Chemical Industry