대장균은 장관 내에 1% 정도 정상적으로 존재하는 세균입니다. 공장식 농장에서 사육되고 있는
반추동물의 약30%는 병원성 대장균 O157:H7을 보균하고 있습니다. 공장식 농장에서는 사료
효율을 높이기 위하여 고농도의 곡물사료를 급여하고 있지요. 옥수수 및 콩 위주의 곡물사료
급여에 따라 가축들의 소화계(장관)에서 대장균이 득실거리는 환경을 조장하고 있습니다.
자세한 내용은 2009년 발표된 아래 논문은 참고하세요.
Diet, Escherichia coli O157:H7, and cattle: a review after 10 years.
Todd R Callaway, M A Carr, T S Edrington, Robin C Anderson and David J Nisbet Curr Issues Mol Biol 11(2):67-79 (2009) PMID 19351974 l
Escherichia coli are commensal bacteria that can account for up to 1% of the bacterial population of the gut. Ruminant animals are reservoirs of the pathogenic bacteria E. colil strain O157:H7, and approximately 30% of feedlot cattle shed E. coli O157:H7. Feedlot and high-producing dairy cattle are fed high grain rations in order to increase feed efficiency. When cattle are fed high grain rations, some starch escapes ruminal microbial degradation and passes to the hindgut where it undergoes fermentation. Ten years ago researchers demonstrated that populations of total E. coli were higher in grain-fed than in forage-fed cattle, and when cattle were abruptly switched from a high grain diet to an all hay diet, total E. coli populations declined 1000-fold within 5 days and reduced the ability of the surviving E. coli to survive an acid shock mimicking passage through the human gastric stomach. This research provoked many questions about the effects of diet or E. coli O157:H7 populations that have not been conclusively answered to date. Subsequent research has shown that diet does affect E. coli O157:H7 populations, but the effects have varied in magnitude and impact. Further studies have demonstrated that the effects of forage feeding on E. coli O157:H7 populations may be due to concentrations of tannins and phenolic acids in forages. Other ration components such as rapidly ruminally fermented grains (e.g., barley) increase the shedding of E. coli O157:H7, and in some situations, feeding distillers grains can increase fecal shedding of E. coli O157:H7 due to VFA concentrations. Data from researchers across North America indicate that diet does impact STEC/EHEC populations in cattle prior to slaughter; however the economic, logistic and practical impacts of dietary changes must be examined and accounted for.
Escherichia coli are commensal bacteria that can account for up to 1% of the bacterial population of the gut. Ruminant animals are reservoirs of the pathogenic bacteria E. colil strain O157:H7, and approximately 30% of feedlot cattle shed E. coli O157:H7. Feedlot and high-producing dairy cattle are fed high grain rations in order to increase feed efficiency. When cattle are fed high grain rations, some starch escapes ruminal microbial degradation and passes to the hindgut where it undergoes fermentation. Ten years ago researchers demonstrated that populations of total E. coli were higher in grain-fed than in forage-fed cattle, and when cattle were abruptly switched from a high grain diet to an all hay diet, total E. coli populations declined 1000-fold within 5 days and reduced the ability of the surviving E. coli to survive an acid shock mimicking passage through the human gastric stomach. This research provoked many questions about the effects of diet or E. coli O157:H7 populations that have not been conclusively answered to date. Subsequent research has shown that diet does affect E. coli O157:H7 populations, but the effects have varied in magnitude and impact. Further studies have demonstrated that the effects of forage feeding on E. coli O157:H7 populations may be due to concentrations of tannins and phenolic acids in forages. Other ration components such as rapidly ruminally fermented grains (e.g., barley) increase the shedding of E. coli O157:H7, and in some situations, feeding distillers grains can increase fecal shedding of E. coli O157:H7 due to VFA concentrations. Data from researchers across North America indicate that diet does impact STEC/EHEC populations in cattle prior to slaughter; however the economic, logistic and practical impacts of dietary changes must be examined and accounted for.
