College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, China.
College of Animal Science and Technology, Northeast Agricultural University, Harbin, 150030, China.
J Dairy Sci. 2019 Feb;102(2):1330-1340. doi: 10.3168/jds.2018-15444. Epub 2018 Dec 26.
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.
本研究旨在评估鼠李糖乳杆菌 GG（LGG；ATCC 53013）对单次给予黄曲霉毒素 B（AFB）的犊牛生长性能和肝毒性的影响，并研究 AFB 在瘤胃液、血液和排泄物中的吸收、分布和消除，以及羟基代谢物黄曲霉 M（AFM）。24 头雄性荷斯坦犊牛按体重和年龄分组，随机分为 3 个处理组之一：（1）未处理对照，（2）用 4.80mg AFB（仅 AFB）处理，或（3）用 1×10cfu 的 LGG 悬浮液和 4.80mg AFB（AFB 加 LGG）处理。在接受单次口服 AFB 之前和当天，犊牛每天通过口服给予 50ml 磷酸盐缓冲液中的 LGG 悬浮液，持续 14 天。在研究开始时（在给予 LGG 之前）、给予 AFB 的当天和试验结束时记录体重。在给予 AFB 后 96 小时内连续采集瘤胃液、血液、尿液和粪便样本。分析平均日增重（ADG）和血浆生化参数，并测定样品中 AFB 和 AFM 的浓度，以监测排泄模式和毒代动力学。结果表明，AFB 处理组的 ADG 较低；LGG 给药部分减轻了 ADG 的降低（0.85±0.08 比 0.76±0.18kg/d）。AFB 处理增加了血浆天冬氨酸转氨酶、碱性磷酸酶和乳酸脱氢酶水平。LGG 的给药减轻了 AFB 诱导的血浆酶活性增加。AFB 和 AFM 的排泄模式非常规律；在单次口服 AFB 后，所有样品中均迅速检测到毒素，毒素浓度峰值依次在瘤胃液、血浆、尿液和粪便中达到（瘤胃液中除 AFM 外），然后呈指数下降。排泄曲线表明，粪便和尿液中 AFB 和 AFM 的浓度最高。LGG 的给药降低了瘤胃液中游离 AFB 和 AFM 的浓度，并减少了毒素向血浆和尿液的释放。LGG 给药降低了毒代动力学参数（除最大浓度时间和终末半衰期外）。总之，在单次给予 AFB 的犊牛中，AFB 和 AFM 的吸收、分布和排泄迅速。尿液是 AFM 的主要排泄途径，从浓度峰值的清除模式通过指数下降函数拟合良好。LGG 的给药通过增加粪便排泄来减少胃肠道对 AFB 的吸收，从而减轻 AFB 的肝毒性。
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