Lactobacillus rhamnosus GG modulates gastrointestinal absorption, excretion patterns, and toxicity in Holstein calves fed a single dose of aflatoxin B.

The aim of the present study was to evaluate the effects of Lactobacillus rhamnosus GG (LGG; ATCC 53013) on growth performance and hepatotoxicity in calves fed a single dose of aflatoxin B (AFB) and to investigate the absorption, distribution, and elimination of AFB and the hydroxylated metabolite aflatoxin M (AFM) in rumen fluid, blood, and excretions. Twenty-four male Holstein calves were blocked for body weight and age and were randomly assigned to 1 of 3 treatment groups: (1) untreated control, (2) treated with 4.80 mg of AFB (AFB only), or (3) treated with 1 × 10 cfu of LGG suspension and 4.80 mg of AFB (AFB plus LGG). The calves received LGG suspension in 50 mL of phosphate-buffered saline daily via oral administration for 14 d before and on the day they received a single oral dose of AFB. Body weight was recorded at the beginning of the study (before LGG administration), at the day of AFB administration, and at the end of the trial. Rumen fluid, blood, urine, and feces samples were collected continuously for 96 h after AFB administration. Average daily gain (ADG) and plasma biochemical parameters were analyzed, and concentrations of AFB and AFM in the samples were determined for monitoring excretion pattern and toxicokinetics. The results showed that ADG was lower in AFB-treated animals; LGG administration partially mitigated the decrease in ADG (0.85 ± 0.08 vs. 0.76 ± 0.18 kg of gain/d). The AFB treatment increased plasma aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase levels. Administration of LGG alleviated the AFB-induced increase in plasma enzymes activity. The excretion patterns of AFB and AFM were surprisingly regular; toxins were rapidly detected in all samples after a single oral dose of AFB, and the peak of toxins concentrations was sequentially reached in rumen fluid, plasma, urine, and feces (except AFM in rumen fluid), followed by an exponential decrease. The excretion curves showed that AFB and AFM concentrations were the highest in feces and urine, respectively. Administration of LGG decreased the concentrations of free AFB and AFM in rumen fluid and reduced the release of toxins into plasma and urine. Toxicokinetic parameters (except for the time of maximum concentration and the terminal half-life) were reduced by LGG administration. In conclusion, the absorption, distribution, and excretion of AFB and AFM were rapid in calves fed a single dose of AFB. Urine was the main route for the excretion of AFM, and the clearance pattern from the peak of concentration was well fitted by exponential decreasing function. Administration of LGG reduced the absorption of AFB in the gastrointestinal tract by increasing the excretion via the feces, thus alleviating the hepatotoxic effect of AFB.