Abstract:
Aflatoxins are toxic secondary metabolites of fungi that may retard growth and cause upsurge in mortality of animals when ingested. Existing toxin binders do not mitigate the inevitably absorbed fraction of the toxins, which may be sufficient to elicit deleterious effects. The use of yeast cell wall beta-glucans with established in vitro aflatoxins binding activity, antioxidants such as selenium, vitamins E and C, and an anti-haemorrhagic agent (vitamin K), in mitigating the impact of aflatoxins in chickens is less explored. Therefore, effects of beta-glucans, antioxidants and vitamin K in reducing cellular oxidative activities that may result from absorbed aflatoxins in broiler chicken were investigated.
Aspergillus flavus 3228 inoculated maize was used to formulate a Basal Diet-BD containing 270ppb aflatoxins. Seven diets comprising Negative Control (NC- aflatoxin-free diet), BD and BD containing beta-glucans at: 125ppm (BD125), 250ppm (BD250), 375ppm (BD375), 500ppm (BD500) and 625ppm (BD625) were fed to 210 one-day-old Arbor Acres Chicks (AAC), replicated thrice with 10 birds each for 42 days. Absorbed Aflatoxins-AA was determined by balance trial method. In another trial, NC, BD and BD containing vitamins: E (VE), C (VC), K (VK) and selenium at 200mg, 250mg, 3mg and 0.3mg/kg diet, respectively in four combinations: R1 (BD+VE+VC), R2 (BD+VE+VC+Se), R3 (BD+VE+VC+VK) and R4 (BD+VE+VC+VK+Se), were fed to 180 AAC, replicated thrice with 10 birds/replicate for 42 days. Serum malondialdehyde-MDA (nmol/mL) and reduced:oxidised glutathione (GSH:GSSG) were measured. Also, NC, BD and combinations of two best treatments each from previous studies: TD1 (BD250+R3), TD2 (BD250+R4), TD3 (BD375+R3) and TD4 (BD375+R4) were fed to 180 AAC for 49 days in augmented (2x2)+2 factorial arrangement. Experimental design was completely randomised. Body Weight Changes-BWC (g/bird) was measured and mortality recorded. At day 49, two birds/replicate were sacrificed for Residual Aflatoxin-RA (µg/kg) determination in liver and Breast Meat-BM by ELISA method.Data were analysed using descriptive statistics and ANOVA at α0.05.
Increased levels of beta-glucans resulted in decreased AA from 98.9±0.5% (BD) to 20.7±8.5% (BD375). Beyond 375 ppm, AA increased to 64.4±2.0% (BD500) and 75.4±2.2% (BD625). Serum MDA ranged between 12.4±10.5 (NC) and 128.2±31.1 (BD). This was significantly reduced by combinations of antioxidants and VK from 128.2±31.1 to 42.0±10.4 (R4), while 79.2±38.6 (R1), 80.1±12.5 (R2) and 72.5±24.9 (R3) were similar and lower than in BD. The GSH:GSSG was highest in NC (3.64±1.44), inclusion of antioxidants with or without selenium and/or VK elevated GSH:GSSG to 1.98±0.89 (R1), 1.94±0.78 (R2), 1.88±0.72 (R3) and 2.19±0.92 (R4) from 0.83±0.58 (BD), which indicated effective mitigation. Combinations of beta-glucans and selenium improved BWC up to 99%, from 956.27±19.34 (BD) to 1,903.98±32.56 (TD4). Mortality was reduced from 39.4±5.3% (BD) to 9.1±5.3% (TD3), 12.1±5.3% (TD4), 21.2±5.3% (TD1) and 24.2±5.3% (TD2). The RA decreased 10-fold, from 2.56±0.34 (BM) and 3.46±0.43 (liver) for BD to 0.23±0.02 in BM (TD3) and 0.35±0.11 in liver (TD4).
Yeast beta-glucans inclusion in aflatoxin-contaminated diet up to 375 ppm reduced aflatoxins absorption and combinations of beta-glucans, vitamins E, C, K and selenium ameliorated theeffects of inevitably absorbed aflatoxins in broiler chicken.
