Then comes their follow-up comment: “I’ve seen lots of grain in the manure, and I don’t want to pay for feed that my cattle can’t use.”

Lane woody
Lane Livestock Services / Roseburg, Oregon
Woody Lane is a certified forage and grassland professional with AFGC and teaches forage/grazing ...

My answer to the first question is the classic “it depends.” Really, it does – mostly on the production level of the cows or calves, their nutrient requirements and the feedstuffs that are available.

And also some practical issues like feeding equipment and if the feed will contain drugs, minerals or other additives. And also, some cattlemen have a very practical reason: They use a grain bucket to attract the cattle and bring them in.

But the response to the second question is not so straightforward. Sure, everyone is startled to see whole corn or barley in the manure – an obvious financial loss.

And cattlemen have been told by so many people – their neighbors, veterinarians and, of course, a million folks on the Internet – that they must process grain to get any good out of it. Well, actually, that’s not true. But processing grain for cattle is a complex situation. Let’s step back and consider some of the issues.

Advertisement

Fiber and starch

Here is the main point: We want to feed cattle – not hogs or chickens or purebred crocodiles. Cattle, like sheep and goats, are ruminants. This is important. Ruminants evolved over millions of years to do one thing extremely well: extract nutrients from feeds that contain lots of fiber.

Ruminants are exquisitely designed to consume forages and other high-fiber plants, re-grind that feed as cud, ferment the fiber into compounds they can use for energy and do it more efficiently than most other animals. That strength has given them a critical evolutionary advantage in a world where feed is often in short supply.

Their rumen is a complex ecosystem of microbes, an oxygen-free environment carefully buffered to a pH of 6.2 or higher, which provides the ideal living conditions for the specialized bacteria that ferment fiber.

Grains, on the other hand, are a horse of a different color. From a nutritionist’s perspective, grains are really packages of starch. Grains also contain some soluble sugars, but they don’t contain much fiber.

On any laboratory report, we identify the amount of fiber in a feedstuff by the amount of neutral detergent fiber (NDF). For example, medium-quality grass contains 50 to 65 percent NDF, mid-bloom alfalfa contains 35 to 45 percent NDF, and corn grains contain only 9 percent NDF. Most of the rest of the grain is starch. (The hard outer shell of shelled corn does not qualify it as a high-fiber feedstuff.)

But when starch is introduced into the rumen, it can cause problems. Plant leaves and stems don’t usually contain much starch, and the rumen was not really designed for starch. Sure, rumen bacteria will ferment most of it, but the starch fermentation pattern is different than with forages.

Starches and sugars ferment more quickly than fiber. This results in a faster release of stronger acids like lactic acid which, if its levels get too high, can overcome some of the rumen buffering capacity and drive down the pH of the rumen fluid, usually to well below 6.

This radically changes the rumen environment. Starch-fermenting bacteria love it, but fiber-fermenting bacteria – the microbes that convert the fiber into usable digestible nutrients – do not. In extreme situations, high levels of starch can cause acute rumen acidosis; low levels of starch can cause the subacute version.

The trouble with acidosis

We all know about acute acidosis. This is what happens when steers get into the grain bin. But subacute acidosis occurs quite frequently with lower levels of starch, quietly, without any obvious symptoms. But in the rumen, fiber digestion declines, and the risk of the acute version goes up dramatically.

And to make things more complex, the various grains carry different risks of acidosis, primarily because of differences in their starch molecules. Starches can differ in their ratios of amylose (unbranched molecules) to amylopectin (branched, crosslinked molecules) which affect their solubility and the speed of fermentation. Wheat ferments faster than barley, which ferments faster than corn.

Cattlemen generally know this in a practical way. They will say that “wheat is a ‘hotter’ feed than corn.” In practice, wheat can be a very risky grain to feed to ruminants.

And many wheat byproducts – bakery waste, old ground-up bagels, etc. – are, from a ruminant nutritionist’s perspective, really feedstuffs composed of finely ground wheat starch.

In the big picture, grains are a two-edged sword. Sure, they increase the risk of acidosis, but those starches and sugars also provide a higher energy level than forages. And for high-producing animals, if the price of grain is low enough, the extra nutritive value is a very powerful reason to use them.

Which brings us back to the original observation. If we feed whole grains to ruminants, some of those grains will end up in the manure. What should we do about it?

This too shall pass

First, how much whole grain is really lost in the manure? Actually, this has been studied. (I have in my mind a picture of teams of graduate students, armed with clipboards and white lab coats, quietly walking in the fields behind some cows, hour after hour, meticulously counting corn grains in each pat of manure.)

But seriously, researchers have found that, even for feedlot cattle on 90 percent grain diets or high-producing dairy cows eating 50 pounds of feed each day, the amount of corn that passes into the manure is generally less than 10 to 15 percent of the amount consumed.

We can prevent much of this loss by processing the grains – rolling, cracking, crimping, steam-flaking, grinding and pelleting (which is also fine grinding with some exposure to heat when the material is forced through the small holes in the pellet die).

In each case, these industrial procedures break open the grain kernels, increase the starch solubility, expose more starch to the rumen microbes and facilitate its fermentation. In other words, processing increases the chances that a greater percentage of starch will ferment faster before the grain washes out of the rumen.

But is processing grain worth the extra costs? Let’s consider three aspects to this question. First, will whole grains provide extra nutrition to cattle? That answer is unequivocally yes. Will processing reduce the loss of grains in the manure?

Again, the answer is yes. Starch becomes more available to the rumen bugs; fermentation is faster; less grain passes undigested through the gastrointestinal tract.

But will processing grains increase nutritional value and give better production? That answer is ... not usually. Research trials with growing calves and lambs often show no effect or even reduced growth when processed grains are compared to whole grains.

Why? This brings us to the second aspect: acidosis. The faster fermentation due to processing brings an increased risk of acidosis, especially subacute acidosis.

The nutritional gains from the processed grains are often offset by reduced fiber digestion, reduced rumen efficiency and other metabolic disturbances due to the increased acid load. Ruminants were not designed for high-starch diets, and processing grains can accentuate problems.

Nutrients lost

The third aspect is arithmetic. If we process grains to save the 15 percent lost in the manure, and processing adds more than 15 percent to the cost of the feed ... well, you can do the arithmetic. Also, processing is not without its own losses. Some material is lost in the industrial dust or as wastage, and even after processing, some grain material may still pass undigested into the manure, except that now we won’t notice it.

There are other factors to consider, of course. Processed grains are generally easier than whole grains to blend into mixed rations and supplements. Pelleting allows a consistent addition of various feed additives and prevents sorting.

And depending on the facilities, processed grains may be easier to handle. And some hard grains, like milo, must be processed or else a lot more than 15 percent will end up in the manure. These points can be very important indeed, especially in larger operations.

Whole grains usually do a fine job of providing some extra nutrition, as well as training the cattle to like you. The 10 to 15 percent loss in the manure is really just a cost of production. Or maybe not. Old-time farmers didn’t let this grain go to waste.

The time-honored technique of pigs following cattle made a lot of sense. Kind of like gleaning, as it were. Farmers raised multiple species of livestock and used this technique to increase the efficiency of their grains. In that sense, we might even consider pigs as a form of grain processing.

So is processing grains for cattle worth it? On the surface, not usually, although it really depends on the balance of pluses and minuses. Personally, I like to play to the cow’s strength – its rumen.

And speaking of strengths, I’m reminded of a quote from Damon Runyon, a famous big-city newspaperman in the early part of the 20th century. He was not a cattleman and he didn’t feed cattle, but he may have summarized our dilemma nicely when he said, “The race is not always to the swift, nor the battle to the strong, but that’s the way to bet.”   end mark

Woody Lane is a livestock nutritionist and forage specialist in Roseburg, Oregon. He operates an independent consulting business and teaches workshops across the U.S. and Canada.

His book, From The Feed Trough: Essays and Insights on Livestock Nutrition in a Complex World, is available through Woody Lane.

PHOTO: Grain feeds are packages of starch and contain soluable sugars. Staff photo.

Woody Lane