Metabolism and Nutrition III: Feed Additives

Aflatoxins (AF) are a class of mycotoxins that impair poultry health and performance by causing immune suppression, liver damage, and changes in serum chemistry. The toxic effects of AF can be efficiently counteracted by some adsorbents. The aim of this study was to investigate fully characterized clay adsorbents in a feeding trial with broiler chickens to correlate in vitro and in vivo AF detoxifying efficacy. A completely randomized design was used with 4 replicate pens of 5 chicks assigned to each of 10 dietary treatments from hatch to 21 days. Dietary treatments evaluated included a negative control diet (no AF), a positive control diet (2 mg/kg AF), and 8 treatment groups receiving 2mg/kg AF and 0.5% of one of 8 adsorbents. Results of in vitro experiments ranked the adsorbents as ′good′ (6 bentonites, R, MB, B7, M32, M34, M5), ′avaerage′ (bentonite C2) or ′poor′ (zeolite Z08). Compared with the negative control, AF caused lower (P<0.05) feed intake (FI) and body weight gain (BWG). The addition of the ′good′ bentonites prevented (P<0.05) the reduction in FI and BWG caused by AF. Adsorbent C2 prevented the reduction in FI (P<0.05) but did not completely prevent the reduction in BWG. Adsorbent Z08 was not effective in reducing or preventing the effects of AF on FI or BWG. Similarly the ′good′ adsorbents prevented the decrease in serum albumin, serum globulin and serum total protein caused by AF. Aflatoxin caused an increase in relative liver weight (LWT) and relative kidney weight (KWT). Adsorbents R, B7, M5, M23 and M34 prevented (P<0.05) the increase in LWT caused by AF. Adsorbents R, MB, B7, M5 and M23 prevented (P<0.05) the increase in KWT observed in chickens fed AFB alone. Adsorbents C2 and Z08 were not able to diminish the negative effects of AF on LWT and KWT. The ability of adsorbents to ameliorate AF toxicity in poultry basically correlated with the in vitro findings meaning that ′average′ and ′good′ adsorbents did not (Z08) or only partially (C2) protected against AF in vivo. However, several in vitro tests are required to differentiate amongst ′good′ AF adsorbents.