Why Grass is Great!
This picture might not seem all that spectacular, a cow on pasture. When you break down the amazing orchestration of what’s actually happening in this picture it is absolutely amazing though. For thousands of years cattle have been in a symbiotic relationship with the microflora that inhabit their rumens. A cow’s rumen gives the bugs a home and a food source. In turn the bugs do for the cow what she couldn’t do on her own: they let her survive and thrive on a high cellulose diet of plant material that would otherwise be undigestible.
If you were to sample the cow in this picture, her ruminal fluid would be close to pH neutral, remaining more or less constant between 6.7 and 6.9. At this pH a whole host of “good guy” bacteria are hard at work in her rumen, breaking down plant fibers and producing volatile fatty acids, B vitamins, protein, and carbohydrates.
Understanding pH and how a seemingly small change in pH actually reflects a very large change in the amount of acid present is important for later in this article. The pH scale is simply a measure of how acidic or how alkaline/basic a substance is. A pH of zero is close to the equivalent of battery acid, whereas a pH of 14 is close to the equivalent of lye. The pH scale is logarithmic, meaning that for each whole number change there is a ten times (or ten-fold) change in the amount of acid or base. For example a pH value of 6 is ten times more acidic than a pH of 7 and a pH of 5 is 100 times more acidic then a pH of 7. This is why the physiological pH (also known as the pH of blood where life is considered compatible) is such a narrow window of 7.3-7.4.
Back to our cow grazing grass. The microflora in that cow’s rumen are adapted to survive at a pH of 6.7-6.9. So what happens when the cow is fed a foreign feed such as grains? The microflora in her rumen are all-stars at fermenting feed, but when that feed changes to a highly and much more easily fermented feed, such as grain or finely chopped hay, they go into overdrive and become their own demise. When fermentation is increased, so are the products of fermentation, including lactic acid. If lactic acid production exceeds the buffering systems in place, the pH begins falling in the rumen, becoming more and more acidic. The good bugs of the rumen get sick and begin to fail and die, and the other bacteria that had been merely getting by in a basic pH begin to thrive at the lower pH. Unfortunately these bacteria also metabolize glucose to lactate, which becomes a very dangerous situation very rapidly. So dangerous that if this were to happen rapidly, for instance in a ration error or when a cow gains access to a large amount of concentrated feed such as a bag of grain, the end result could very well be death.
If this acidifying process happens slowly though (as it does when cattle are put on feed for showing, feedlots, or dairy production), the outcome is different. In the case of feedlot calves the long term outcomes are rarely noted because they are slaughtered prior to the full development of clinical signs. Putting calves less than 14 months “on feed” has been shown to have deleterious effects on their long term survival and productivity. Bull purchasers have acknowledged this for years and many range cattle operations will not purchase grain backgrounded bulls due to the knowledge that they will “have had their feet burnt out from under them”. This is due to the fact that many cattle subjected to grain diets and the resulting ruminal acidosis will go on to have either subclinical or clinical laminitis. This is well demonstrated in dairy herds and in feedlots where the incidence of subclinical laminitis reaches nearly 100%.
If you don’t have good sound feet and legs under a cow or bull, regardless of how much the animal is worth, all you have is a slaughter animal. Cattle are large, heavy animals and clinically lame cattle become a serious humane issue. It is important to note that some animals with subclinical laminitis will show no outward signs of lameness, but can be diagnosed with radiographs or after death by measuring sole thickness and amount of digital rotation. This is part of the reason that many heavily fed breeding animals will show no signs until they are introduced into a situation where they must travel farther distances or over rough country. The example of the corn fed bull that gets turned out on the range and becomes completely lame and worthless is a good illustration of this.
Unfortunately, laminitis is one of the few ways that intensive feeding is visually recognized, but the unseen consequences are just as grim. When the rumen of a cow becomes acidotic, the good bugs are killed and bad bacteria invade. These “bad guys” produce a substance known as endotoxins. Endotoxins have many negative effects on the body, including making blood vessels “leaky”. Leaky blood vessels are implicated in the pathogenesis of laminitis as well as the other syndromes associated with ruminal acidosis. Most cattle that suffer from laminitis will also have liver abscesses. Liver abscesses are created when the bad bacteria are able to travel to the liver and colonize there. If the bacteria are able to escape the liver they are capable of colonizing the heart valves, lungs, joints, and kidneys. All of these can result in disease processes of the effected organs including; endocarditis, pneumonia, arthritis, and pyelonephritis. Many of these diseases are hard, if not impossible, to diagnose while the animal is alive but many of them can be diagnosed after the animal is slaughtered or dies. Sometimes the presentation of these problems will manifest rather dramatically with a dead cow with no outward reason for her being dead. Other times cows will present as chronic poor doers–they won’t gain well, they won’t milk well, they just aren’t “right”. It has always been greatly ironic to me that the process of feeding cattle up can result in them being lifelong poor doers.
Breeding cattle are fed concentrate rations for a couple reasons: to show them off to buyers and to show them. Fat cattle look better than thin or moderately fleshed cattle for the reason that fat hides flaws in conformation. The old saying that “the best color on a horse is fat” holds true in this case as well. The show standard for cattle is fat. If you tried to tell someone you were going to show grass fat calves they would laugh you out of the show ring, because grass fat isn’t the same as corn fat or pushed rate of gain. I am not completely condemning showing, but I will in good conscience issue a very stern warning to buyers and breeders to be aware when you know you are dealing with concentrate fed cattle. I will also issue a suggestion that all sellers be upfront and forthright, with what their feeding program is, when selling cattle. If you try to hide behind an all natural or grass fed front your grain fed cattle will rat you out.
I know that some people reading this article will believe it is biased because we are known to be a grass based program with grass based genetics. I will say that the truth is quite the contrary; we choose grass based genetics and run a grass based program because of the facts stated in this article: concentrate feeding cattle negatively affects a herd’s long-term productivity and profitability. . I also know that this article may be interpreted that I am against showing. I am not against showing but do believe that those who choose to feed their cattle concentrated rations should be aware of the potential outcomes and implications that it can have, not only for the individual cow but for the breed as a whole.
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Why Grass is Great!