Assessment of Pb retention coefficient and nutrient utilization in growing pigs fed diets with added clinoptilolite

The main objective of this study was to measure the retention coefficient of lead (Pb) from clinoptilolite, of Greek origin, in a balance trial with growing pigs. Twelve weaned pigs of 45 days of age were divided into two equal groups. The first group was fed a control (C) diet and the other (the experimental E group) the same diet added with 20 g clinoptilolite of volcanic origin/kg. The Pb content of the clinoptilolite used was 46 ppm, and the dietary contents were 1.1 and 2.1 ppm for diets C and E, respectively. Feed intake, growth rate and feed conversion efficiency, as well as digestibility and nitrogen (N) retention were measured to investigate any effects of the dietary inclusion of clinoptilolite in pigs. Pb concentration was measured in whole blood and edible parts of the carcass (muscles, liver, heart and kidneys), and Pb retention coefficient was determined. The results showed that digestibility did not differ between diets C and E, apart from that of ether extract, which was lower (P < 0.01) for the C diet, whereas, N retention was higher in pigs of group E. No significant differences were observed for feed intake, growth rate and feed efficiency. The retention coefficient of Pb from clinoptilolite was found to be 0.009, whilst the retained Pb in edible parts of the pig carcass was negligible. In conclusion, this particular clinoptilolite used at a level of 20 g/kg in diets of growing pigs has no deleterious effect on feed intake and growth rate, and does not lead in a significant increase of Pb concentration in blood and edible tissues, owing to its low retention rate. Thus, its use as binder in pig's diets is safe for animals and for consumers.