NUTRITION PIH-3 PURDUE UNIVERSITY. COOPERATIVE EXTENSION SERVICE. WEST LAFAYETTE, INDIANA Dietary Energy for Swine Authors Palmer J. Holden, Iowa State University Gerald C. Shurson, University of Minnesota James E. Pettigrew, University of Minnesota Reviewers Richard C. Ewan, Iowa State University John P. Hitchcock, University of Tennessee William G. Luce, Oklahoma State University Pigs require energy to maintain normal body processes, to grow and to reproduce. Feeds supplying energy are major com- ponents of all swine diets, and the quantity of diet voluntarily consumed by pigs is related to its energy content. Carbohydrates from cereal grains are the most abundant energy source in swine diets. Fats and oils contain more energy than carbohydrates per unit weight but are included to a lesser extent. Amino acids, or protein, may serve as an energy source if included in the diets in excess of animals' requirement for protein synthesis. The value of a feedstuff is based on several factors: pala- tability (how well the material will be consumed by an animal), availability of energy and the feed's contribution of other nutrients (protein or amino acids, vitamins, minerals). Should a pork producer buy corn, wheat, or oats as a feed ingredient? This depends primarily on the cost of these ingredients and their value as sources of energy and other nutrients for the pig. Measurement of Energy To make sound decisions in selecting feed ingredients, it is desirable to have an understanding of the system by which feedstuffs are rated for energy content and the use of these rat- ings toward meeting the energy requirements for pigs' growth and production. The gross energy (GE) of a feed ingredient is defined as the heat produced when a substance is burned. It is expressed as calories per unit weight. A calorie is the amount of heat required to raise the temperature of one gram of water from 14.5 to 15.5 degrees C. A kilocalorie (kcal) is 1,000 calories, and a megacalorie (mcal) is a million calories. Not all of the feed consumed is digested and absorbed. Some energy is lost in the fecal material (Fig. 1). Thus, GE is a poor estimate of energy for the pig. The amount of energy remaining after subtracting the fecal energy loss from total energy intake is designated as digestible energy (DE). The difference between GE and DE may be large. The greater the digestibility of energy (DE/GE) the greater its value as a source of energy to the animal. DE is a more meaningful measure for livestock producers than GE. Metabolizable energy (ME) is the "usable" energy of a feed for the pig to live and grow and is obtained by subtracting the urinary energy loss from the DE. In most cases, metabolizable energy represents approximately 95% of the digestible energy con- tent, so the conversion from DE to ME can be made easily. Some energy is released as heat as a result of inefficien- cies in the metabolism of the nutrients. This is called the heat increment (HI). It can be used only to keep the animal warm; heat increment produced beyond that needed to maintain body tempera- ture is wasted. The remaining energy is called net energy (NE) and is used for maintenance (NEm) and production (NEp). Determi- nation of NE values requires special equipment and/or animal feeding trials. Major Energy Sources Cereal Grains The basic energy sources for swine are the cereal grains: corn, sorghum grain (milo), barley, wheat, oats and their by- products. Cereal grains are high in carbohydrates (starch), palatable and highly digestible. Usually they contain less lysine and other amino acids, minerals and vitamins than swine require. The diets therefore must be supplemented with other feeds to increase these nutrients to recommended levels. Grain by-products have many characteristics of their origi- nal source but tend to be bulkier and have less metabolizable energy. Although their protein content usually is increased, the protein quality often is rather poor. Corn contains less protein but more energy than the other cereals. Like all cereals, the composition of corn is influenced by variety, growth conditions, method of harvesting and storage. Because of its abundance and readily available energy, corn is used as the base grain for comparing the nutritive value of other cereal grains. Grinding is recommended except for high moisture corn. Sorghum grain is similar in quality to corn and can com- pletely replace corn in swine diets. Its energy value is about 95% of the value of corn except for some bird-resistant varieties which may be only 80% to 90% of the value of corn. Grinding is recommended because the grain is rather small and hard. Barley contains more protein and fiber than corn. High qual- ity barley has 90% to 100% of the feeding value of corn, but it may be less palatable. Wheat is equal to corn in feeding value and is very palat- able when it is medium to coarsely ground in complete rations. Wheat can completely replace corn in swine diets. Oats contain more protein than corn, but their value in swine diets is only 90% of corn because of their higher fiber and lower energy content. Fats and Oils Fats and oils contain about 2.25 times as much metabolizable energy per pound as cereal grains, but they are more expensive. Fats are available commercially in products such as bleachable fancy tallow, prime tallow, yellow grease, hydrogenated vegetable fat and various dry fat products which include fat and a dry car- rier. Fat sources should be protected from rancidity by an antioxidant. There do not appear to be major differences in dietary value among the fat sources, except for very young pigs which may not utilize the harder animal fats as well as softer vegetable fats. Vegetable oils and the dry fat products tend to be more expensive than animal fats. Supplemental fat is difficult to mix in on-farm mixing facilities, especially in cold weather. Fat changes the physical characteristics of a swine feed. Feed containing added fat is somewhat sticky and therefore tends to bridge in bulk bins and feeders. It tends to "oil out" of paper bags and reduce pellet hardness. These problems increase as the fat level increases and become severe when the added fat exceeds 6% of the feed. Added fat reduces dustiness and therefore improves the environment in swine buildings. Certain biological effects also can be expected when fat is added to diets of starting, growing and finishing pigs. These include: improved palatability, reduced feed consumption, signi- ficant improvement in feed efficiency, slight increase in growth rate, increased carcass fatness at high fat levels and high lev- els of vegetable oils causing a softening of carcass fat. Pigs' responses to fat may be greater in warm or hot environments than in cool environments. Fat has a lower heat increment than carbohydrates and proteins and is less likely to cause reduced feed intake during heat stress. When fat is added to a swine diet, the amount of feed con- sumed usually decreases. However, animals' needs for other nutrients remain relatively constant when expressed on a daily basis. Therefore, to maintain performance when fat is added to the diet, the concentration of other nutrients should be increased. The decision to add fat is an economic one. If improvement in growing-finishing swine preformance more than offsets the cost of adding fat, it is economical. Typically, adding 1% fat to the diet results in approximately 2% better efficiency. When the piglet survival rate is below 85%, supplementing the sows' diet with fat during late gestation may improve sur- vival rate. The added fat must provide at least 2.0 lb. to 2.5 lb. of fat to each sow prior to farrowing. This appears to be a response to fat and not to increased energy intake. The added fat increases the fat content of the colostrum and milk which is responsible for the increased survival rate. Adding fat to lacta- tion diets increases voluntary ME consumption, but only slightly reduces the weight loss in the sows. It increases weaning weights of the litters due to increased fat in the milk. There is no evi- dence that added fat improves subsequent reproductive preformance of sows. Fiber Content Some energy sources are relatively high in fiber and reduce gain and efficiency if fed at excessive levels. Pigs 40 lb. and heavier usually can tolerate up to 5% of a high-fiber feed such as alfalfa in their diet without a noticeable effect on perfor- mance. As pigs mature, more and more low energy-high fiber feeds can be fed, especially to sows during gestation and post-weaning. Fiber feeds such as wheat bran and beet pulp may be useful in gestation and farrowing diets because of their laxative effects, but should constitute no more than 5% of a lactation diet. Fiber has a high heat increment and during cold stress this heat can be utilized to maintain body temperature, thus, less is wasted. Therefore, there is a smaller difference in relative values between fibrous grains (such as barley or oats) and corn in cold weather. Conversely, in hot weather the high heat incre- ment becomes a problem for the pigs' cooling ability. Moisture Content High-moisture grains contain less energy per pound of feed because of the water content. More pounds of high-moisture grain must be used to get the same amount of dry matter. Studies with high-moisture grains fed in complete diets indicate similar per- formance to dried grain when efficiency is measured on a dry matter basis. Free-choice feeding of grain and supplement often results in poorer efficiency. See PIH-73, High Moisture Grains for Swine. Grinding With the exception of high-moisture corn, grinding improves feeding efficiency for all grains, especially high-fiber grains such as oats or barley. Finer grinding usually results in improved efficiency, although finely ground corn increases the incidence of ulcers in finishing swine. Fine grinding is most advantageous for pigs under 40 lb. Wheat is very palatable when it is medium to coarsely ground in complete rations since high levels of finely ground wheat in diets has been associated with lowered palatability due to pastiness of the meal. See PIH-71, Physical Forms of Feed. Pelleting Pelleting a diet may increase gains by 5% and feed effi- ciency by 5% to 10%. A high-energy cereal such as corn or sorghum benefits less from pelleting than fibrous feeds like barley or oats. When a complete diet is purchased, pelleted diets may be more economical than meal diets. However, the advantage of pel- leting probably will not offset the cost of hauling grain from the farm to a pelleter and home again. Relative Value In selecting energy sources for swine diets, also consider protein quality and content. Because the amino acids lysine, tryptophan, threonine and methionine can be limiting in swine diets, levels of these amino acids on cereal grains affect their overall value. Although sugar, molasses and fats or oils are energy sources, they provide little or no protein to the diets. The amount of feed per unit of gain is not the most impor- tant factor in swine nutrition. Cost per unit of gain is more important; therefore, it is necessary to use the most economical feed sources available in swine diets. The relative feeding values shown in Tables 1 and 2 can be used to determine which ingredient is most economical. For example, if corn costs 5.0 cents per pound, barley is worth about 4.5 cents per pound (5.0 cents x 90%). If barley can be purchased for less than this, it is a better buy. ______________________________________________________________________ Table 1. Relative feeding values of energy sources1. _________________________________________________________________ Metabo- Relative Maximum recommended lizable feeding percent of complete diets3 energy value vs. Gesta- Lacta- Ingredient (air dry) kcal/lb. corn,% 2 tion tion __________________________________________________________________ Alfalfa meal dehydrated 775 70-80 50 5 Alfalfa meal sun-cured 800 60-70 50 5 Animal fat stabilized 3585 185-210 10 6 Bakery surplus material 1650 95-110 40 40 Barley (48 lb/bu) 1380 90-100 80 80 Beet pulp, dried 1020 70-80 10 5 Brewers dried grains 1000 90-100 40 5 Buckwheat 1200 80-90 50 0 Corn yellow 1550 100 80 80 Corn (high lysine) 1520 100-105 90 90 Corn and cob meal 1300 80-90 70 0 Corn distillers dried grains 1540 115-130 40 10 with solubles Corn gluten feed 1285 74 90 5 Corn grits by-product (hominy)1400 100-105 60 60 Emmer 1140 80-90 20 0 Sorghum grain (milo)4 1480 95-100(4) 80 80 Millet (Proso) 1230 90-95 80 80 Molasses (77% D.M.) 1060 55-65 5 5 Oats (36 lb/bu) 1240 85-95 80 5 Oat groats 1550 115-125 0 0 Potatoes (22% D.M.) 370 20-25 80 0 Rice grain 1070 75 40 0 Rye 1300 90 20 0 Spelt 1180 85 40 0 Sugar 1383 70-80 0 0 Triticale 1450 90-95 80 80 Wheat, hard 1475 100-105 80 80 Wheat, soft 1500 90-95 80 80 Wheat, high protein 1500 100-105 80 80 Wheat bran 980 60-65 30 5 Wheat middlings 1340 125-140 30 5 Wheat, dried 1405 135-145 5 5 __________________________________________________________________ Contd ...Table 1. _________________________________________________________________ Maximum recommended percent of complete diet3 Starter Grow- Remarks Ingredient (air dry) finish __________________________________________________________________ Alfalfa meal dehydrated 0 5 Good source of B vitamins Alfalfa meal sun-cured 0 5 Unpalatable to baby pigs Animal fat stabilized 5 10 High energy, reduces dust Bakery surplus material 20 40 High energy, variable salt content Barley (48 lb/bu) 25 85 Corn substitute, lower energy Beet pulp, dried 0 0 Bulky, high fiber, laxative Brewers dried grains 0 10 High fiber, B-vitamin source, low lysine Buckwheat 0 50 Not to light colored pigs outdoors Corn yellow 60 85 High energy, low lysine Corn (high lysine) 60 90 Lysine analysis recommended Corn and cob meal 0 0 Bulky, low energy Corn distillers dried grains 5 10 B-vitamin source, low lysine with solubles Corn gluten feed 5 25 Low lysine Corn grits by-product (hominy)0 60 Subject to rancidity Emmer 0 0 Sorghum grain (milo)4 60 85 Low lysine Millet (Proso) 60 85 Low lysine Molasses (77% D.M.) 5 5 Low energy, partial grain substitute Oats (36 lb/bu) 0 20 Low energy, partial grain substitute Oat groats 20 0 Palatable Potatoes (22% D.M.) 0 30 Must be cooked, low protein Rice grain 0 20 Low energy, low lysine Rye 0 25 Possible ergot toxicity, low palatability Spelt 0 25 Low energy, low lysine Sugar 5 0 High palatability, no protein Triticale 20 85 Possible ergot Wheat, hard 60 85 Low lysine Wheat, soft 60 85 Low lysine Wheat, high protein 60 85 Low lysine Wheat bran 0 0 Bulky, high fiber, laxative Wheat middlings 0 10 Partial grain substitute Wheat, dried 20 5 High lactose content, variable content ____________________________________________________________________ 1Based on an air dry basis unless otherwise noted. High moisture feedstuffs must be converted to an air dry equivalent of 88-90% dry matter to determine energy and substitution rates. Complete data on all ingredients are not available. 2When fed at no more than maximum recommended % of complete diets. Relative values based on metabolizable energy, lysine and phosphorus content using simultaneous equations. Example: ME Lysine Phosphorus Price ___________________________________________________________ 1550X + .024Y + 0.25Z = $/cwt. corn 1460X + 2.90Y + 0.60Z = $/cwt. soybean meal (44%) 0X + 0Y + 18.50Z = $/cwt. dicalcium phosphate Determine values for X, Y, and Z and multiply them times the M.E. (kcal/lb), % lysine, and % phorphorus of feed in question and sum the values. 3Higher levels may be fed although performance may decrease. 4Some bird resistant sorghums are 80-90% vs. corn. ______________________________________________________________________ ______________________________________________________________________ Table 2. Relative feeding values of protein sources1. _____________________________________________________________________ Metabo- Relative Maximum recommended lizable feeding percent of complete diets3 energy value vs. Gesta- Lacta- Ingredient (air dry) kcal/lb. 44% soybean,%2 tion tion _____________________________________________________________________ Blood meal, flash dried 1200 185-200 5 0 Buttermilk, dry 1400 75-85 0 5 Canola meal (solvent) 1200 75-85 5 5 Corn gluten meal 1395 40-60 5 5 Cottonseed meal, solvent 1150 65-75 5 5 Distillers dried solubles 1180 65-70 5 5 (corn) Feather meal, hydrolyzed 1000 60-70 3 3 Fish meal, anchovy 1120 140-165 5 5 Fish meal, menhaden 1500 140-165 5 5 Fish solubles (50% solids) 780 50-60 3 3 Linseed meal 1280 55-65 5 5 Meat and bone meal 1035 95-110 10 5 Peanut meal, expeller 1400 70-80 5 5 Skim milk, dried 1620 95-100 0 0 Sorghum gluten meal 1460 40-55 5 5 Soybeans, whole, cooked 1640 90-100 30 25 Soybean meal, solvent 1460 100 25 20 Soybean meal, solvent, 1535 110-112 22 18 dehulled Tankage (meat meal) 980 115-130 10 5 Yeast, brewers dried 1400 100-105 3 3 ______________________________________________________________________ Contd ..Table 2. ______________________________________________________________________ Maximum recommended percent of complete diet3 Starter Grow- Remarks Ingredient (air dry) finish ______________________________________________________________________ Blood meal, flash dried 5 5 Low isoleucine, unpalatable Buttermilk, dry 20 5 Good amino acid balance Canola meal (solvent) 5 10 Toxic problem at high levels Corn gluten meal 0 5 Low lysine Cottonseed meal, solvent 0 5 Gossypol toxicity, low lysine Distillers dried solubles 5 5 B-vitamin source, low lysine (corn) Feather meal, hydrolyzed 0 3 Low lysine Fish meal, anchovy 5 5 Excellent amino acid balance Fish meal, menhaden 5 5 Excellent amino acid balance Fish solubles (50% solids) 3 3 Excellent amino acid balance Linseed meal 5 5 Low lysine Meat and bone meal 5 5 Low lysine, tryptophan and methionine, good phosphorus Peanut meal, expeller 0 5 Low lysine Skim milk, dried 20 0 Excellent amino acid source, palatable Sorghum gluten meal 0 5 Low lysine Soybeans, whole, cooked 40 30 Similar to soybean meal, but may produce soft pork Soybean meal, solvent 35 22 Similar to soybean meal, dehulled Soybean meal, solvent, 30 20 Good amino acid balance with dewhulled corn Tankage (meat meal) 0 5 Low digestibility, unpalatable Yeast, brewers dried 3 3 Source of B-vitamins _____________________________________________________________________ 1Based on an air dry basis unless otherwise noted. High moisture feedstuffs must be converted to an air dry equivalent of 88-90% dry matter to determine energy and substitution rates. Complete data on all ingredients are not available. 2When fed at no more than maximum recommended % of complete diet. Relative values based on metabolizable energy, lysine and phosphorus content using simultaneous equations. Example: ME Lysine Phorphorus Price ___________________________________________________________ 1550X + 0.24Y + 0.25Z = $/cwt. corn 1460X + 2.90Y + 0.60Z = $/cwt. soybean meal (44%) 0X + 0Y + 18.50Z = $/cwt. dicalcium phosphate Determine values for X, Y, and Z and multiply them times the M.E. (kcal/lb), % lysine, and % phosphorus of feed in question and sum the values. 3Higher levels may be fed although performance may decrease. _____________________________________________________________________ ______________________________________________________________________ List of Figures: Figure 1: Partition of energy in nutrition. REV 6/91 (5M) ______________________________________________ Cooperative Extension Work in Agriculture and Home Economics, State of Indiana, Purdue University and U.S. Department of Agri- culture Cooperating. H.A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the Acts of May 8 and June 30, 1914. It is the policy of the Cooperative Extension Service of Purdue University that all persons shall have equal opportunity and access to our programs and facilities.