Post by wyomama on Feb 6, 2007 0:03:05 GMT -5
Shawn asked for a further clarification of my response to the Hannah Wallace article Ther Udder Truth posted under In the News. In that post I stated that E. coli H7:0157 is characteristic of the hindgut (colon) not the rumen as is often stated elsewhere.
To non cow people it is not going to make much difference where in the cow E. coli is found. However there is significance for us as I will try to explain.
The dangerous strain was not observed before about 1988. It first appeared in feedlot cattle which as by now we are all aware are fed a diet consisting almost entirely of corn and soy. This creates acid conditions both in the rumen and all the way down the gut. However E. coli as the name suggests is adapted to the colon. There are a great many strains of E.coli. Typically they are adapted to live in the nearly neutral environment of the healthy cow colon and die quickly in acid conditions. But now through mutation or some other means a new form has emerged to fill a new environmental niche, the acid colon. That is about as much as anybody knows about where E. coli H7:0157 came from.
We do, however, know how to get rid of it. This is by feeding hay or permitting grazing. The colon of a cow on her natural diet quickly reverts to a neutral pH which kills H7:0157.
The rumen dislikes excessive acidity for an array of reasons having to do with its job of fermenting fiber to produce fatty acids and proteins. All the work of the rumen is done by specialized bacteria and protozoa. It is these which break down cellulose (fiber) and produce acetic acid which is absorbed directly through the rumen wall. The cow depends on acetic acid to make milk. Already this sounds complicated and I am oversimplifying!
A healthy rumen contains several populations of bacteria, each specialized to ferment a different part of the diet. Besides being able to ferment cellulose (fiber) which is the whole point of being a cow, plenty of carbohydrates (starches and sugars) are always eaten and must be digested. Fresh green grass contains lots of sugars/carbs. As the hours, the days and the seasons pass the proportions of fiber and carbohydrate constantly change.
The rumen is not a passive organ. Its specialist populations of bacteria surge and crash according to the cow’s diet. E. coli are not adapted to the tasks performed by normal rumen bacteria. If the cow gets a dose of E. coli, any kind, perhaps because of drinking from a contaminated pond, she may become ill as these wrong bacteria interfere with digestion. Obviously this will affect milk production and weight gain and will not be tolerated for long either by the cow or by the farmer.
The cow prospers perfectly well when E. coli, any kind, occupy the colon where they belong.
A diet of almost entirely corn and soy does indeed cause an acid rumen. It will literally put the rumen out of business and will ulcerate the rumen wall and the cow will die. To slow down this outcome, some fiber must be fed. Michael Pollan has written effectively about feedlot steers which are grown and fattened in a race with death on this unnatural diet. On such a diet it is possible to build muscle and add fat by essentially converting the steer into a pig. You would not be able to produce milk on this diet because cows produce milk by converting fiber. Confinement dairies always feed enough fiber to keep the rumen functional but they feed as much grain as they can get away with. Confinement cows cud less and by the end of their lactation often have ulcerated rumens and a lot of other things wrong with them. Some confinement dairies are experiencing high counts of E. coli H7:0157. Nobody seems to know how it found its way to them but they are now spreading it around for the rest of us to worry about.
Our cows that have hay and grazing are eating in the way for which they are designed and are not at much risk of ever having the bad E. coli. I would have said never at risk were it not for the chance of contamination from the above sources.
Now here is why I hope you read this far. Many people who are justly outraged by feeding practices which put at risk both human health and rumen function are reluctant to feed any grain at all for fear it will distort the natural climate of the rumen. However, in the normal course of events cows eat and thrive on all kinds of plants besides grass. Besides a huge variety of broad leafed plants found in pasture, they eat carrots and the seeding heads of grasses and my baby apple trees. Many things that cows eat are high in carbohydrates that you might think could pervert the rumen. Molasses especially comes to mind. But this seldom happens because as already mentioned, the rumen is not a passive organ. The bacterial population, if not suddenly challenged with large amounts of a new food, soon has a busy population of microorganisms on the job to digest whatever it is presented with. This includes grain in amounts sufficient to support milk production and maintain body weight as necessary. Kelsey has reported that her Iris bloats on even small amounts of grain but this is a rarity.
I hope this has advanced understanding of this important topic somewhat. A cow is not tiptoeing along a narrow fence line in the matter of rumen acidity. She is adapted to quite a wide variety of feeds so long as we don’t overwhelm her with carbs. A healthy cow’s rumen delivers nicely buffered kimchee to her true digestion and consequently her colon does not provide a hospitable environment for E. coli H7:0157.
A cow would be at a great disadvantage if her rumen could not deal with a varied and frequently changing diet. The colon is indeed a passive organ and must just accept what is delivered to it. So it is acid in the colon, not the rumen, that should be our concern.
Joann
To non cow people it is not going to make much difference where in the cow E. coli is found. However there is significance for us as I will try to explain.
The dangerous strain was not observed before about 1988. It first appeared in feedlot cattle which as by now we are all aware are fed a diet consisting almost entirely of corn and soy. This creates acid conditions both in the rumen and all the way down the gut. However E. coli as the name suggests is adapted to the colon. There are a great many strains of E.coli. Typically they are adapted to live in the nearly neutral environment of the healthy cow colon and die quickly in acid conditions. But now through mutation or some other means a new form has emerged to fill a new environmental niche, the acid colon. That is about as much as anybody knows about where E. coli H7:0157 came from.
We do, however, know how to get rid of it. This is by feeding hay or permitting grazing. The colon of a cow on her natural diet quickly reverts to a neutral pH which kills H7:0157.
The rumen dislikes excessive acidity for an array of reasons having to do with its job of fermenting fiber to produce fatty acids and proteins. All the work of the rumen is done by specialized bacteria and protozoa. It is these which break down cellulose (fiber) and produce acetic acid which is absorbed directly through the rumen wall. The cow depends on acetic acid to make milk. Already this sounds complicated and I am oversimplifying!
A healthy rumen contains several populations of bacteria, each specialized to ferment a different part of the diet. Besides being able to ferment cellulose (fiber) which is the whole point of being a cow, plenty of carbohydrates (starches and sugars) are always eaten and must be digested. Fresh green grass contains lots of sugars/carbs. As the hours, the days and the seasons pass the proportions of fiber and carbohydrate constantly change.
The rumen is not a passive organ. Its specialist populations of bacteria surge and crash according to the cow’s diet. E. coli are not adapted to the tasks performed by normal rumen bacteria. If the cow gets a dose of E. coli, any kind, perhaps because of drinking from a contaminated pond, she may become ill as these wrong bacteria interfere with digestion. Obviously this will affect milk production and weight gain and will not be tolerated for long either by the cow or by the farmer.
The cow prospers perfectly well when E. coli, any kind, occupy the colon where they belong.
A diet of almost entirely corn and soy does indeed cause an acid rumen. It will literally put the rumen out of business and will ulcerate the rumen wall and the cow will die. To slow down this outcome, some fiber must be fed. Michael Pollan has written effectively about feedlot steers which are grown and fattened in a race with death on this unnatural diet. On such a diet it is possible to build muscle and add fat by essentially converting the steer into a pig. You would not be able to produce milk on this diet because cows produce milk by converting fiber. Confinement dairies always feed enough fiber to keep the rumen functional but they feed as much grain as they can get away with. Confinement cows cud less and by the end of their lactation often have ulcerated rumens and a lot of other things wrong with them. Some confinement dairies are experiencing high counts of E. coli H7:0157. Nobody seems to know how it found its way to them but they are now spreading it around for the rest of us to worry about.
Our cows that have hay and grazing are eating in the way for which they are designed and are not at much risk of ever having the bad E. coli. I would have said never at risk were it not for the chance of contamination from the above sources.
Now here is why I hope you read this far. Many people who are justly outraged by feeding practices which put at risk both human health and rumen function are reluctant to feed any grain at all for fear it will distort the natural climate of the rumen. However, in the normal course of events cows eat and thrive on all kinds of plants besides grass. Besides a huge variety of broad leafed plants found in pasture, they eat carrots and the seeding heads of grasses and my baby apple trees. Many things that cows eat are high in carbohydrates that you might think could pervert the rumen. Molasses especially comes to mind. But this seldom happens because as already mentioned, the rumen is not a passive organ. The bacterial population, if not suddenly challenged with large amounts of a new food, soon has a busy population of microorganisms on the job to digest whatever it is presented with. This includes grain in amounts sufficient to support milk production and maintain body weight as necessary. Kelsey has reported that her Iris bloats on even small amounts of grain but this is a rarity.
I hope this has advanced understanding of this important topic somewhat. A cow is not tiptoeing along a narrow fence line in the matter of rumen acidity. She is adapted to quite a wide variety of feeds so long as we don’t overwhelm her with carbs. A healthy cow’s rumen delivers nicely buffered kimchee to her true digestion and consequently her colon does not provide a hospitable environment for E. coli H7:0157.
A cow would be at a great disadvantage if her rumen could not deal with a varied and frequently changing diet. The colon is indeed a passive organ and must just accept what is delivered to it. So it is acid in the colon, not the rumen, that should be our concern.
Joann