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Feeding Small Grains to Swine

by 5m Editor
7 November 2005, at 12:00am

By Zebblin Sullivan, Animal Science, Iowa State University; Mark Honeyman, Professor, Department of Animal Science; Lance Gibson, Associate Professor, Department of Agronomy; Jean McGuire, Editor, Educational Materials and Marketing Services and Micki Nelson, Designer, Educational Materials and Marketing Services - Small grains, such as barley, oats, rye, triticale, and wheat can be useful feedstuffs in swine feeding programs. In many instances, pigs fed well-balanced small grain-based diets can perform as well as those fed corn-based diets.

Contents

  • Introduction
  • Nutrient Composition of Small Grains
  • Bedding
  • Possible Challenges of Feeding Small Grains to Swine
  • Barley
  • Oats
  • Rye
  • Triticale
  • Wheat
  • Guidelines Summary

Introduction

Nutritionally, small grains are similar to corn in some aspects, but there are differences depending on the grain. Small grains are higher in crude protein than corn and, more importantly, they are higher in lysine, the fi rst limiting amino acid in cereal grainbased swine diets. Small grains are also higher in digestible phosphorus than corn, but tend to be lower in energy content.

When viewed in the context of an integrated crop and livestock system, several additional attributes also make small grains attractive. Addition of an extra crop to the corn soybean rotation typical of the U.S. Corn Belt can reduce costs, improve distribution of labor and equipment, improve yields of corn and soybeans, provide better cash flow, and reduce weather risks. Lengthening the time between crops on the same ground can decrease the prevalence of some pests, most notably soybean cyst nematode and corn rootworm. Straw from small grains is an excellent source of bedding that becomes available in the late summer when corn stalks stored since the previous fall may be in poor condition. Small grains also provide environmental benefits, such as erosion control and improved nutrient recycling. Proper grain testing and diet formulation are important aspects of maximizing the performance of small grains as swine feed. Growing and harvesting conditions can greatly infl uence the nutritional composition of small grains even within the same variety. Testing for lysine concentration is especially important because improper protein supplementation is a major cause of problems when feeding small grains.

The first section of this publication provides information and guidelines common to inclusion of barley, oats, rye, triticale, and wheat in swine diets. The middle section contains information specifi c to the feeding of each small grain species to the various classes of swine. The last section contains summarized guidelines for including small grains in swine diets. The information should be consulted carefully as some small grains should only be fed in limited amounts in certain situations. University swine extension specialists and company-based or independent swine nutritionists can be contacted for more information on feeding small grains to swine.

Nutrient Composition of Small Grains

Small grains contain more crude protein than corn and greater levels of several essential amino acids, including lysine, threonine, and tryptophan (Table 1). The higher lysine concentration in small grains is especially important. Lysine is the fi rst limiting amino acid in many swine diets, so balancing the diet on the basis of lysine content usually provides adequate levels of the other essential amino acids. Compared to corn, small grains contain 30 to 50% more lysine, which reduces the need for soybean meal in small grain-based fi nishing diets by about 100 lb/ton. This increases the feed value of small grains relative to corn by 5 to 7%. Lysine concentration is the most important consideration when balancing small grain-based swine diets with protein or amino acid supplements. Balancing on crude protein alone is often ineffective because the amount of lysine relative to protein varies among small grains and corn. If lysine concentration is unknown, substituting small grains for corn on an equal weight basis would be a conservative approach for constituting swine diets.

The phosphorus (P) in small grains is more available to swine than that in corn, which provides both economic and environmental benefits. Even though cereal grains contain significant amounts of P, much of it is chemically bound within phytate. Since pigs lack the enzymes needed to remove P from phytate, inorganic P must be added to the diet to meet the pig’s requirement for this mineral. Dicalcium phosphate, the most common P source, is an expensive ingredient. Feeding grains with more available P reduces the amount of inorganic P supplementation in the diet, which minimizes negative environmental impacts connected with excessive P in swine manure. Most of the phosphorus locked in phytate is excreted in the manure and makes its way into streams and lakes if it is spread on erodible farmland already high in soil P. Since the P in small grains is more available than that in corn, there may be up to 30% less P secreted by animals fed small grains. Phosphorus availability is 10 to 15% in corn, 20 to 30% in barley and oats and 45 to 50% in triticale and wheat.


Small grains are lower in fat, higher in fi ber, and typically contain less metabolizable energy than corn (Table 1). Rye, triticale, and wheat contain 5 to 10% less energy than corn, but these differences do not appear to have negative effects on average daily gains when fed in fi nishing diets. In many studies, these grains have successfully replaced 100% of the corn used in control diets. The lower energy has affected feed effi ciency in some instances because pigs on small grain diets ate more than pigs on corn-based diets. When palatable, pigs generally consume higher amounts of small grains to meet their energy requirements. Barley and oats have higher fiber content than other small grains because the kernels are encased in a hull. The higher fi ber content of barley does not appear to negatively affect gains in growing-fi nishing swine if plump, high-test weight grain is fed. However, high fi ber content lowers oats’ feed value to about 80% of that of corn. Lower energy limits the use of oats to only a portion of swine diets, but the high fi ber can be useful for adding bulk to the diets of gestating sows.

Barley and oats also have relatively high heat increment content. Heat increment is the increase in heat production from digestion of feed. High heat increment of a feedstuff can help keep an animal warm in cold environments, hence feeding oats and barley during the winter may be advantageous. However, in hot conditions, feeding oats and barley may decrease feed intake, because the additional heat generated by the fi brous feeds is not needed by the animal.

Bedding

Straw from small grain makes excellent bedding for pigs. Oat straw is one of the most absorbent bedding types commonly available. Oat straw is about 10% more absorbent than pine saw dust or shredded corn stalks. Wheat and triticale straw are about 25% less absorbent than oat straw. Barley straw is about 33% less absorbent than oat straw. Good straw should be clean, bright, and free of mold or dust. Shredded barley straw is preferred for fl oating biocover for manure storage structures. Because straw is an important economic component of a small grain crop, it should be harvested in a timely manner.

Possible Challenges of Feeding Small Grains to Swine

Ergot. Ergot is most common in rye, and is only occasionally found in barley, oats, and wheat. This does not mean it cannot be a problem in these grains under certain conditions. A serious ergot infestation of barley occurred in northeast Iowa in 1996. Rye is particularly susceptible to ergot infestation and should be fed with extreme caution. Ergot is caused by a fungus that regularly infests wild and cultivated grasses in Iowa and other humid areas. Ergot produces dark purple to black sclerotia (bodies) that replace the grain in the heads and contaminate the harvested grain. Grain with more than 0.1% ergot sclerotia (about 1 body in 1000 kernels) should not be fed to growing-fi nishing swine unless it is diluted to lower levels with ergot-free grain. Ergot concentrations above this level can reduce feed intake, slow growth, and reduce feed conversion. If fed at levels that are too high, ergot can even cause death. Grain containing any ergot should not be fed to breeding stock.

Ergot sclerotia contain alkaloids, which stimulate contraction of small blood vessels. Early symptoms of ergot poisoning include animal lameness, usually in the hind limbs, appearing a few weeks after fi rst ingesting ergot. Continued ergot consumption results in gangrene and sloughing of tissue extremities such as the nose, ears, tail, and limbs. Ingestion of very low levels of ergot by lactating animals markedly reduces, and may stop, milk production. Occasionally ergot alkaloids affect the animal’s nervous system causing convulsions and staggering.

Symptoms vary with ergot alkaloid content, amount ingested, frequency of consumption, and the climatic conditions during sclerotia growth. Some ergot sclerotia are similar to the grain kernels in size, while others are larger. A large size difference between the sclerotia and the grains allows for removal of the ergot bodies with grain cleaning equipment.

In triticale research at Iowa State University, ergot levels varied greatly with variety and growth environment. In most cases, ergot levels were not problematic in winter triticales. However, most spring varieties had ergot levels near or greater than 0.1%. AC William was the only spring triticale variety with ergot levels as low as wheat. Ergot is most prevalent in areas and seasons with wet soil surface conditions during spring and early summer combined with rainy weather during flowering.

To minimize ergot infestation, select low ergot varieties and avoid planting small grains in fi elds that contained pasture or forage grasses the previous growing season. Scab. All small grains can be infected with the fungus Fusarium graminearum resulting in what is commonly called scab. With severe Fusarium infection, the grain becomes shriveled and takes on a chalky white or pink appearance. Scab is most likely to occur under cool, wet weather during early summer. Scabby grain can contain unacceptable levels of deoxynovalenol (DON) or vomitoxin, a mycotoxin associated with feed refusal in swine. Pigs fed diets having harmful DON levels will gain slowly and have poor feed effi ciency. Contaminated grain should not be fed to gestating or lactating sows or pigs weighing less than 50 lb. For growing-fi nishing swine, contaminated grain may be blended with noncontaminated grain to reduce the DON concentration below 1 ppm, usually a no effect level. Cattle and other ruminants may be better alternatives for feeding scab infested small grains because they are less sensitive to DON than swine.

Enzyme inhibitors: Some varieties of rye and triticale contain excessive levels of antinutritional compounds that interfere with the activity of trypsin and chymotrypsin, enzymes that assist the digestion of proteins. Inhibition of these enzymes reduces gain, diminishes muscle growth, and negatively affects pancreatic health. Trypsin inhibitor levels vary widely among rye and triticale genetic lines. Newer triticale varieties have acceptable trypsin inhibitor levels, thus their use in swine diets should not be limited by these factors.

Low-test weight: Less than ideal growing and harvesting conditions can lower small grain test weight. Low-test weight grain has higher fi ber content and lower energy density than high test weight grain. Pigs fed lowtest weight grain may gain poorly or have poorer feed effi ciency versus those fed high test weight grain. Test weight differences may account for the variability in pig performance found among oat feeding trials. It has been commonly accepted that oats should not constitute more than 20% of a growing-fi nishing pig diet. However, research with high-test weight oats (at least 36 pounds per bushel) at Iowa State University found that oats could make up 40% of the diet without affecting pig performance. Low-test weight oats are best used as a feedstuff in gestating sow diets or as a small percentage of fi nishing diets where feed intake usually is not the limiting factor.

To read the full article, including tables, please click here (PDF)

Source: Published by Iowa State University - June 2005

Iowa State University
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