The livestock industry has always competed with other sectors of the economy for corn and other feed ingredients. The most common example is the broad use of corn in the human food sector, where the grain is used for everything from breakfast cereals to sweeteners.

Generally, growth in the human food and livestock sectors occurred at a balanced pace. But, more recently, the very rapid growth of another competitor — the biofuels sector — has disrupted this balance. Consequently, as oil prices rose, the price and availability of corn followed, and the brunt of the escalating demand was felt by everyone associated with livestock feeding.

And, as human food and biofuel manufacturers tapped into more and more of the corn supply, the creation of new coproducts was a natural result. The human food sector generated bakery byproducts, corn gluten meal, corn gluten feed, distillers' grains and distillers' solubles, to name a few. The biofuels sector has dramatically increased the availability of corn distillers' dried grains, with or without solubles added. The increased use of corn for fuel has therefore focused more attention on feeding these by-products to pigs.

As swine feeding programs began adding more coproducts to traditional corn-soybean meal blends, new questions on how to evaluate their nutrient value surfaced. The fact that coproducts typically are less consistent in their composition and nutrient availability makes this task even more difficult.

European producers have a long history of using coproducts in pig diets. Table 1 offers some perspective on how the composition of U.S. swine diets differs from those in the European Union and The Netherlands.

Whereas typical U.S. swine diets have contained about 65% cereal grains (corn, milo, wheat, barley — depending on the region) and 20% coproducts of oilseed processing, namely soybean meal, the Europeans have used much smaller quantities of cereal grains and much higher quantities of coproducts from both the oilseed and human food industries.

While corn and soybean meal will likely remain the staple ingredients in practical U.S. swine diets in the foreseeable future, there is no denying that coproducts will play a bigger role. The survival of the pig industry demands it.

When corn reached the unimaginable price of $8/bu. last year, the volatility on the market was clearly demonstrated. Even though grain prices have settled back to more historically typical levels, we must be prepared for such dramatic changes in the future.

Adaptability in feed markets is important for another reason. The use of alternative feed ingredients gives pork producers more options in their feeding programs; more options generally translate into greater success.

Evaluating New Ingredients

As the market conditions change and producers consider new ingredients, they must understand their chemical composition, including energy, amino acids, vitamins and minerals. Not all nutrients in an ingredient are biologically available, so studies are required to measure the availability of energy, amino acids and phosphorus. Although other nutrients may be of interest, these are the most critical in basal ingredients.

Evaluating energy values is complicated by at least two unique issues. First, energy is not a single entity, but rather a compilation of four energy sources — starch, fats, fiber and protein. Each energy source is used by the pig in different ways.

For example, most starch is digested fairly easily and absorbed from the intestinal tract as glucose, an efficient energy source. However, some starch is resistant to digestion and passes through the small intestine and becomes fermented into volatile fatty acids in the lower gut. Volatile fatty acids are not used as an energy source as efficiently as glucose.

Nutritionists are just beginning to understand the portion of starch in a raw feedstuff that is resistant to digestion. Unfortunately, very little is known about how processing, such as drying, affects the portion of starch that is resistant.

Determining the availability of amino acids and phosphorus also presents technical challenges, but generally accepted procedures are useful and fairly accurate in providing this information.

Amino acids are used less efficiently for energy than starch because amino acids have to be broken down by the pig to remove the nitrogen molecule. There is a metabolic cost to this process, and the issue is further complicated by the fact that amino acids used to create proteins, such as lean tissue or enzymes, are not available as an energy source. Thus, we can see that amino acids used as energy are less efficient than starch, and the exact quantity available to be used as energy is uncertain.

On average, about 60-65% of the amino acids in a pig's diet are not used to build protein, so those are potentially available as an energy source.

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