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摘要
Nitrite is regulated as an undesirable substance in animal feed. "Products and by-products from sugar beet and sugarcane" are currently exempted from maximum limits. Technological work by the European sugar producers showed that the levels of nitrite in feed materials from sugar plant processing is variable without allowing a stringent control at the full-scale factory process.
The German Sugar Association (VdZ) reviewed the physiological-toxicological data base on nitrite in ruminants considered by EFSA (2009): The established toxicological endpoint of nitrite is oxidized hemoglobin (methemoglobin) that leads to a lack in oxygen supply. The review revealed that the NOAEL (No Observed Adverse Effect Level) of 3.3 mg nitrite/kg bw/day in ruminants is based on a 1940 study with 990 mg nitrate/kg bw in cattle in which nitrite is not mentioned. As auxiliary, a nitrite dose of 99 mg/kg bw was imputed, nitrite considered as being 10 times more toxic, and an uncertainty factor of 3 applied. Published physiological data, however, suggest that such a nitrate dose would be associated with a much higher nitrite exposure and support a lower toxicity of nitrite.
To substantiate this assumption, cannulated cows received 7.5 mg nitrite/kg bw/day over a period of 7 days. After dosage, the expected transient increase of nitrite in ruminal fluid was observed that disappeared 1.5 h after dosage. No relevant increase in methemoglobin was observed. From this study, it can be concluded, that repeated feeding of 7.5 mg nitrite/kg bw to cows did not result in adverse effects. The dosage corresponded to 5.5 g nitrite intake per day and would cover the exposure from molasses with 500 mg nitrite/kg when the other feed contained 10 mg nitrite/kg. The data are supportive that nitrite is a normal metabolite in ruminants that does not require a regulation as contaminant in feed for ruminants.
- 出版日期2018-6-1
