Killing the pathogen
By Sharon OmahenUniversity of GeorgiaUniversity of Georgia scientists have developed a method foreliminating the harmful E. coli O157:H7 pathogen in cattlewatering troughs.An estimated 73,000 cases of E. coli O157:H7 in humans arereported each year in the United States. Studies have shown thatthe pathogen can be transferred from one cow to another throughthe animals’ drinking water. Safer, but not as tastyHe found that the cows drank 19 liters per day of the lactic acidwater, compared to 30 liters per day of nontreated water.”They’ll drink the treated water, but obviously, they’rereluctant to drink it,” he said. “So it’s not suited forcontinuous feeding.”West said cows could survive on the reduced water intake. Butwhen a cow’s water or feed intake is reduced, her growth and milkproduction also decline.To keep from reducing cows’ water intake, the scientistsrecommend farmers periodically treat their water tanks with thechemical treatment.”A farmer could treat his tanks for 20 minutes and basicallysanitize his watering system,” Doyle said. “He could treat theholding tanks and the troughs, then flush and refill them withclean water. This would kill the organism and then provide freshwater for the animals.”Adding the chemical to his cattle’s water supply would be anadded task and, for now, a voluntary action for the farmer, Doylesaid. Searching for the best controlThe best treatments were a combination of lactic acid, acidiccalcium sulfate and caprylic acid and another combination oflactic acid, acidic calcium sulfate and butyric acid.”Both treatments include a base chemical, acidified calciumsulfate, or Safe2O,” Doyle said. “This chemical has avery lowpH, less than 2, which makes it very acidic.”Doyle’s laboratory studies found that the two chemicalformulations not only eliminated E. coli O157:H7, but also killedother enterohemorrhagic E. coli which are related to E. coliO157:H7.But what do the cows think of this new power-drink? UGA animalscientist Joe West fed the treated water to a group of test cows.”We use Calan doors, which are electronically controlled doors,”he said. “Each cow has a transponder that works as the door’skey.”In this way, West can monitor how much water a cow trulyconsumes. For the study, he measured how much water the cowsdrank over seven days and compared that to what theynormally drink. Ready when needed”Until someone down the line gets serious about controlling E.coli at the source, this is just a control method available tofarmers,” he said. “If on-farm controls should be mandated, wehave a treatment available that will work.”Adding the chemicals to cattle drinking water shouldn’t becost-prohibitive for farmers.”The material is fairly dilute, and we’ve determined that a verydilute combination can still be effective” Doyle said. Contaminating drinking water”Cattle drinking water is often contaminated with cud (rumencontent),” said Michael Doyle, a UGA microbiologist and directorof the Center for Food Safety in Griffin, Ga. “Cattle water canalso have manure in it, and together, this leads to E. colicontamination.”In the past, disinfectants like chlorine have been ineffective atremoving E. coli O157:H7 from cattle drinking water. With fundingfrom the American Meat Institute Foundation, Doyle led a projectthat focused on identifying practical treatments for eliminatingE. coli O157:H7 in cattle drinking water.The UGA scientists first screened various chemicals in searchof an effective control.”We knew right away that chlorine and ozone treatments had littleto no effect,” Doyle said. “But we were able to ultimatelyidentify two chemical combinations that are highly effective.”
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