AFLATOXINS (AF) are secondary metabolites produced by certain fungi belonging to the genus Aspergillus and can occur as natural contaminants of poultry food (Leeson et al 1995, O˘ guz 1997). The toxicity of AF in broiler chickens has been widely investigated (Giambrone et al 1985, Dafalla et al 1987, Espada et al 1992, Fernandez et al 1994, O˘ guz et al 2000). As well as the carcinogenic and mutagenic effects of AF, their growth inhibitory effects have economic impor- tance for the broiler industry and these have also been well described (Kubena et al 1993, Santurio et al 1999, O˘ guz and Kurto˘ glu 2000). Removing AF from contaminated food and foodstuffs remains a major problem and there is a great demand for effective decontamination technology (Leeson et al 1995, Boutrif and Canet 1998). In the last 10 years, several studies have been performed to detoxify AF in contaminated food and foodstuffs and to minimise the deleterious effects of AF in broilers (Kubena et al 1990, 1993, Harvey et al 1993, Jindal et al 1994, Abo-Norag et al 1995, Bailey et al 1998) and other poultry species (Sjamsul et al 1990, Kubena et al 1991, Parlat et al 1999). The non-nutritive clays such as alu- minosilicates (Kubena et al 1990, 1993, 1998, Ledoux et al 1999), zeolites (Scheideler 1993, Kececi et al 1998), ben- tonites (Araba and Wyatt 1991, Santurio et al 1999) and clinoptilolite (CLI; Harvey et al 1993, Parlat et al 1999, O˘ guz and Kurto˘ glu 2000, O˘ guz et al 2000) were preferred by the researchers because of their high binding capacities against AF and their reducing effect on AF-absorption from the gastrointestinal tract. These are also generally inert and non-toxic to animals (Olver 1997). A protective effect against AF was observed in most of the experiments. Although many adsorbents studies have been performed by greater levels of AF (2 to 5 ppm) and a short-term (21-day) period in broilers, there is little information about the preventive efficacy of the adsorbents against the lower AF levels and long-term experimental periods. Determination of the preventive effectiveness of adsor- bents in lower AF concentrations, which naturally occurred in field conditions, is important for animal health. Surveying studies have demonstrated that the AF levels in broiler food ranged from 5 to 100 ppb in Turkey (Kaya 1982, Acet et al 1989, Coksoyler et al 1992, Ozkazanc et al 1992, Nizamlioglu 1996) and some other countries (Hegazy et al 1991, Kichou and Walser 1993, Pitet 1998). However, gen- erally, the determined values cumulated less than 50 ppb in broiler food in these studies. The objective of the present study was to evaluate the toxic effects of two levels (50 and 100 ppb) of AF on performances of chicks during one broiler period and to determine the preventive effectiveness of simultaneously-added CLI at a level of 15 g kg –1 to both AF-containing diets. MATERIALS AND METHODS Chickens and diet Five hundred and seventy-six 1-day-old Ross broiler chicks of both sexes were obtained from a commercial hatchery. Individually weighed chicks were divided at random into six groups. There were six replicates of 16 broiler chicks for each of six dietary treatments, totalling 576 chicks. The chicks were housed in heated batteries under fluorescent lighting and were fed a commercial food starter (maize and soybean based, 230 g protein, 13·80 MJ ME kg –1 ) up to 21-days, a grower diet (215 g protein, 13·60 MJ ME kg –1 ) up to 42 days. Preventive efficacy of clinoptilolite in broilers during chronic aflatoxin (50 and 100 ppb) exposure H. OG ˘ UZ*, V. KURTOG ˘ LU†, B. COS ¸KUN† Departments of Pharmacology and Toxicology, and †Animal Nutrition and Nutritional Diseases, Faculty of Veterinary Medicine, University of Selçuk, 42031 Kampüs, Konya, Turkey SUMMARY This study was conducted to evaluate the protective efficacy of clinoptilolite (CLI, a natural zeolite) in the prevention of toxic effects of aflatoxin (AF). A total of 576 1-day-old Ross broiler chicks were housed in six treatment groups [six replicates of 16 each; con- trol, CLI (15 g kg –1 diet), 50 parts per billion (ppb) AF, 50 ppb AF plus CLI, 100 ppb AF, 100 ppb AF plus CLI] for 42 days. Compared to controls, 100 ppb AF treatment significantly decreased body weight gains of chicks. The addition of CLI to the 100 ppb AF- containing diet moderately reduced the adverse effects of AF on performances of chicks. The chicks consuming 50 ppb AF-contain- ing diet showed no significant differences on investigated parameters compared to controls. Also, the single addition of CLI to the AF-free diet had no adverse effects in birds. These results suggest that CLI can be beneficial in broilers for protection of AF toxicity at the level above. © 2000 Harcourt Publishers Ltd 0034-5288/00/050197 + 05 $35.00/0 © 2000 Harcourt Publishers Ltd *Corresponding author. Research in Veterinary Science 2000, 69, 197–201 doi:10.1053/rvsc.2000.0417, available online at http://www.idealibrary.com on