EVALUATION OF BACILLUS SPP. AS DIRECT FED MICROBIAL (DFM) CANDIDATES FOR AFLATOXIN B1 BIODEGRADATION IN BROILER CHICKENS.

The limits of physical and chemical methods to decrease aflatoxins in feed ingredients, stimulated the search on biological approaches of degradation. Recently, we identified three Bacillus spp. candidates that showed in vitro activity to biodegradate aflatoxin Bl (AFB1). The aim of this study was to evaluate the biodegradation potential of previously selected Bacillus spp. provided as a direct-fed microbial candidate (DFM), in broiler chickens consuming feed containing different concentrations of AFB1. In the present study, three independent experiments were conducted. In Exp 1, broilers were allocated randomly to four groups: Control feed; feed + DFM; feed + 2 ppm AFB1; feed + DFM + 2 ppm AFB1. Each group had six replicates of 20 chickens (n = 120/group). In Exp 2, broilers were allocated randomly to six groups: Control feed; feed + DFM; feed + 1 ppm AFB1; feed + DFM + 1 ppm AFB1; feed + 1.5 ppm AFB1; feed + DFM + l.5 ppm AFB1. Each group had 5 replicates of 16 chickens (n = 801 group). In Exp 3, broilers were allocated randomly to six groups: Control feed; feed + DFM; feed + 50 ppb AFB1; feed + DFM + 50 ppb AFB1; feed + 500 ppb AFB1; feed + DFM + 500 ppb AFB1, each group had 5 replicates of 10 chickens (n = 801 group). In all experiments, chickens were fed starter (dl-d7) or grower diet (d8-d21) ad libitum until the end of the experiment at day 21. All broilers were individually weighed and body weight (BW), body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were obtained weekly. The results of the present study show clear evidence, that not all DFM are the same, and in this case, administration of 106 spores/gram of feed showed no beneficial performance effects in two out of three independent experiments. In addition, even though the individual isolates incorporated in the DFM showed some in vitro activity to biodegradate AFB1, when administered in the diets at 5 different concentrations of AFB1, no significant performance differences were observed when compared with their respective control diets. [ABSTRACT FROM AUTHOR]