Relative efficacy of bentonite-montmorrilonite and dried yeast cells as biosystemic sequestering agents at high dietary aflatoxin load in turkey poults

Aflatoxin (AFL) is sporadically experienced in poultry diets, resulting in depressed performance. Thus additive binders or active biomolecules suppressive to AFL noxious effects are routinely supplemented to practical feeds. Nevertheless, there is little comparative data on the relative efficacies of available supplements. Therefore we compared the efficacy of proprietary Bentonite-Montmorillonite (Bioad®) and dried yeast cells (Promotop®) used in the industry to prevent or alleviate aflatoxicosis. Turkey poults were used for this investigation.

 

Methods: One hundred and ninety-two 14 d poults were distributed in a completely randomized design to 6 diets, 4 replicates and 8 poults per experimental unit. Treatments were: diet 1 (positive control, as uncontaminated standard diet, PC), diet 2 (negative control, NC), made by partial replacement of uncontaminated corn in the PC with corn cultured with toxigenic Aspergillus flavus to achieve 150 ppb total AFL), diet 3 (NC + 1.5 g/kg Bioad®), diet 4 (NC+ 3 g/kg Bioad®), diet 5 (NC + 1.5 g/kg Promotop®), diet 6 (NC + 3 g/kg Promotop®). Aflatoxin level was confirmed in individual diets by gas liquid chromatographic analysis. Data were subjected to analysis of variance and means were separated based on Duncan multiple range tests (5% α-value). All animal procedures were approved by animal welfare regulations unit and conducted in accordance with the guide for the care and use of agricultural animals in research and teaching (FASS, 2010).

 

Results: At d 44, high dietary ingestion of aflatoxin was detrimental to feed intake, BW gain and fcr (P < 0.05). These parameters, however, were significantly improved relative to NC by both supplements at each level evaluated (P < 0.05), although their benefits could not match the PC in terms of BW gain (P < 0.05). Aflatoxicosis resulted in 56% mortality in the unsupplemented diet which was attenuated to 0 in both diets supplemented with Bioad®, while the use of Promotop® reduced mortality to 12% and 0 in diets 5 and 6, respectively. On the other hand blood haematology and serum biochemistry assayed were not sensitive to aflatoxin intoxication. We interpreted the efficacy of each agent as the slope of a second order polynomial fitted to the BW gain (g/30 d) and daily intake of each agent in mg/30 d (Figure 1, left). F test (5% α-value) showed that the supplements had similar efficacy at the levels tested (P > 0.05). However, the marginal efficiency computed as the first derivative of the polynomial fit suggested different utilization efficiencies (Figure 1, right).

 

Conclusion: This study demonstrated that 150 ppb AFL is toxic in poults and could be ameliorated by dietary supplementation of the tested sequestering agents but at varying efficiencies which decreases with increasing rate of intake.