ارزیابی تاثیر متقابل آفلاتوکسین B1 و جاذب‌های سم آلومینوسیلیکاته بر فراسنجه‌های تولیدگاز، تخمیر و هضم شکمبه در شرایط برون‌تنی

به منظور ارزیابی تاثیر متقابل آفلاتوکسین b1 (afb1) و جاذب‌های سم آلومینوسیلیکاته بر فراسنجه‌های تولیدگاز، تخمیر و هضم شکمبه در شرایط برون‌تنی پژوهشی در قالب دو آزمایش انجام گرفت. در آزمایش اول ابتدا تاثیر مقادیر مختلف afb1 بر فراسنجه‌های تولید گاز، تخمیر و هضم با استفاده از روش کشت ثابت بررسی شد. نتایج نشان داد با افزایش مقدار afb1 از صفر به 900 نانوگرم در میلی‌لیتر، نرخ تولید گاز، پتانسیل تولید گاز، غلظت نیروژن آمونیاکی و قابلیت هضم کاهش یافت، ولی افزودن afb1 به محیط کشت تاثیری بر ph نداشت. در آزمایش دوم تاثیر متقابل afb1 و سه نوع جاذب‌ آلومینوسیلیکاته شامل مگاباند، مایکوباند و میلباند (در سطح 6 درصد ماده خشک جیره) بر فراسنجه‌های تولیدگاز، تخمیر و هضم شکمبه با استفاده از روش کشت ثابت بررسی گردید. نتایج بدست آمده نشان داد که بر خلاف انتظار، هیچکدام از جاذب‌ها نتوانستند تاثیرات منفی afb1 بر فراسنجه‌های تولید گاز، تخمیر و هضم شکمبه ای در شرایط برون‌تنی را خنثی نموده و یا کاهش دهند که احتمالاً به‌دلیل مکانیسم جذب سطحی جاذب‌های آلومینوسیلیکاته برای جذب afb1 باشد. نتایج این پژوهش بیان می‌کند که جاذب‌ها نمی‌توانند اثرات منفی afb1 بر گوارش و تخمیر شکمبه را کاهش دهند و تنها راهکار پیشنهادی برای کاهش اثرات منفی afb1 بر تخمیر، جلوگیری از ورود این سموم به خوراک دام می‌باشد.

Effect of Aflatoxin B1 and Aluminosilicate Toxin Adsorbents on the Parameters of Gas Production, Fermentation and Ruminal Digestion (in vitro)

Introduction: When aflatoxin contaminated food is given to lactating animals, the metabolite of aflatoxin, called M, is secreted in milk. Since pasteurization, sterilization, and milk processing have little effect on the survival and reduction of AFM1 toxicity, this poison ultimately transports to various dairy products and endangers consumer health. Along with the negative effects of mycotoxins on health and livestock products, these compounds can to be effective in digestion, metabolism and ruminal microbial populations. In ruminants (especially lactating cows) fed with AFB1 contaminated feeds, health problems such as liver cancer, reduce immunity, reproductive disorders, malformation, decreased feed intake and milk production have also been reported. An increase in liver enzymes can be attributed to the signs of an abnormal body. In addition, previous studies aluminosilicate has been show to tightly bind aflatoxins in vitro. This significantly reduce mortality and morbidity in animals, decrease molecular biomarkers of aflatoxin exposure in humans and animals.Materials and Methods: Two experiments were conducted to investigate the effect of aflatoxin B1 and aluminosilicate toxin adsorbents on the parameters of gas production contains gas production potential (b) and gas production rate (c), in vitro fermentation parameters includes pH, ammonia nitrogen concentration, volatile fatty acids and ruminal digestion. In the first experiment, the effects of different levels of AFB1, including 0, 300, 600 and 900 ng/ml, were investigated on the parameters of gas production, fermentation and digestion using batch culture method. In the second experiment the effectiveness of three aluminosilicate adsorbents on the AFB1 detoxification was investigated. MegaBond and MycoBond as native adsorbents and MilBond as a commercial adsorbent were used in 6% of DM. The gas produced was recorded at 2, 4, 6, 8, 12, 16, 24, 48, 72 and 96 h of the incubation. The data obtained were fitted to the nonlinear equation to calculate parameters of gas production. Also, at the end of 24 h incubation, four bottles were transferred to refrigerator to stop fermentation. Then, pH, ammonia nitrogen concentration and volatile fatty acid (VFA) of batch culture medium was measured, as well as the dry matter digestibility.Results and Discussion: Results of first experiment indicated that with increasing the AFB1 from 0.0 to 900 ng/ml, the gas production rate (c) decreased from 0.134 to 0.092 ml/h and the gas production potential (b) decreased from 160.7 to 131.3, but there was no significant difference between the treatments 0 and 300 ng/ml AFB1. In addition, the gas production lag phase increased significantly with increasing level of AFB1 (P lt،0.05). Addition of AFB1 to the batch culture did not affect its pH, but the dry matter digestibility significantly decreased (P lt،0.05) with increasing AFB1. Ammonia nitrogen concentration decreased significantly (P lt،0.05) with AFB1 addition, so that the lowest concentration of ammonia nitrogen was observed at 600 and 900 ng/ml AFB1 (15.2 and 15.3 mg/dL, respectively). In this experiment the total VFA concentration decreased significantly with AFB1 (P lt،0.05), but the molar ratio of acetate, propionate, butyrate, valerate and isovalerate was not affected (P gt،0.05). In the second addition of different aluminosilicate adsorbents significantly reduced the rate and potential of gas production. Likewise, dry matter digestibility and ammonia nitrogen concentration reduced significantly (P lt،0.05). Significant increase in pH of the culture medium by addition of aluminosilicate adsorbents can be attributed to the fact that aluminosilicate acts as a modifier of hydrogen ion in the environment due to the replacement of cations with hydrogen ion and prevents a significant decrease in rumen pH. Probably lowering the ammonia nitrogen concentration is due to the fact that the protozoan population is affected by aluminosilicate adsorbent and decreases، consequently, the population of the ruminal bacteria increases, which results in the removal of more ammonia nitrogen by microorganisms, and ultimately the concentration ammonia nitrogen decreases in the rumen.Conclusion: The results of this study showed that AFB1 reduced gas production rate (c), the gas production potential (b), the concentration of ammonia and digestibility, but the pH is not affected in vitro. Also, none of the adsorbents was able to neutralize or reduce the negative effects of AFB1 on the parameters of gas production, fermentation and rumen digestion, which could be due to the absorption mechanism of aluminosilicate adsorbents for AFB1 absorption. The results of this study indicate that adsorbents cannot reduce the negative effects of AFB1 on digestion and rumen fermentation, therefore only proposed strategy is to prevent the contamination animal feed with mycotoxins.