Evaluation of Spent Bleaching Clay as a Feed Supplement in Broiler Diets

Spent bleaching clay, a bentonite product from canola oil refining, was fed to 651 broiler chickens aged 0 to 4 weeks in diets containing 2.8 to 3.1 kcal/g apparent metabolizable energy (AME). Up to 7.5% spent clay could be included successfully in the diet with no deleterious effects on feed intake, growth rate, or feed efficiency (gain/feed intake). Toxicological studies involving mortality, the weight of organs, bone ash percentage, and histopathology of tissues revealed no adverse effects. The AME was 2.87 kcal/g (dry matter basis). The product had beneficial effect on pellet hardness. Reclaimed oil gave slightly poorer growth than refined oil but had no toxic effects. Spent clay did not influence broiler skin color significantly, although unused clay had a marked adverse effect. The results suggest that spent bleaching clay could be added to poultry feed at .5 to 2% clay, which is similar to the amount of bentonite clay used currently.