Potential of Tanzanian local clay and ash based materials for binding aflatoxins in animal feeds

Abstract

Potential of Tanzanian local materials was explored for alleviating aflatoxin-contamination of feeds. Preliminarily, farmers’ awareness of aflatoxins was assessed using data collected from a random sample of 258 households in Meru District in Arusha, Tanzania. An in-vitro experiment, was used to evaluate aflatoxin-binding capacity of test materials (TMs); clays from Arusha (AC), Kilimanjaro (KC), Coast (CC) and Morogoro (MC) and ash-materials identified as volcanic ash (VA) and rice-husk ash (RA) in buffered solution. The TMs were compared for binding capacity with a reference-binder (Mycobind ® , R). An in-vivo complete randomized experiment was used to evaluate aflatoxin-binding capacity of the TMs in reducing bioavailability of dietary aflatoxins using 109 rats in unbalance eight groups. On basal diet, dietary treatments DAC, DKC, DCC, DMC, DVA, DRA, each containing 2% of one of the TMs, DR containing 2% of R and DC (control) were formulated. One rat-group was fed one of the diets. Effects of the diets on feed intake (FI), growth rate (GR), feed conversion efficiency (FCE), packed-cell-volume (PCV), serum-total protein, albumin, globulin and albumin/globulin ratio (AGR) and parameters of liver, kidney and spleen of the rats were assessed. About 52%, 8% and 32% of respondents were aware that fungal toxins may occur in feeds, be transferred into foods of animal origin and are detoxifiable, respectively. About 28% of the respondents had ever heard about aflatoxins. Significantly (p<0.05), ≥secondary education, biological/life science exposure and short-time in livestock industry, positively influenced farmers’ awareness of aflatoxins. Statistically, in-vitro aflatoxin-binding capacity of RA (84.7%) or AC (72.6%) was comparable to that of R (98.1%). Each of TMs could bind >94% of aflatoxin-B1.Statistically, FCE (16.6%) of DKC and AGR of DVA (1.2) were comparable to that of DR (17.5%, 1.2), respectively. Relative weight of liver of DRA (3.8%) was statistically normal comparable to that of DR (3.7%). Only DVA showed normal tissues of liver, kidneys and spleen. Farmer’ awareness of aflatoxins was low, calling for more sensitization. Based on the in-vitro and in-vivo experiments, RA seems to be the best aflatoxin-binding material. Further testing of the TMs using farm animals and their combined performance effect are recommended.