The University of Georgia College of Agricultural & Environmental Sciences
Cooperative Extension Service

Practical Swine Feeding Ideas

Rick Jones, Extension Animal Scientist

Contents

Supplying Basic Nutrients
Special Considerations in Each Production Phase
Combining Ingredients to Meet Nutrient Needs
Common Problems in Georgia Swine Rations

The cost of feed required to produce a pound of live hog is 60 to 80 percent of total production costs. Reducing feed costs per pound of gain will always be a major objective of the successful pork producer.

This publication discusses the nutrients in practical swine diets and the special swine feeding considerations in every production phase. Guidelines are given for combining ingredients to provide those nutrients in the proper quantities with high-quality, economical feed sources. A brief discussion of common nutritional problems in Georgia is also included.

Supplying Basic Nutrients

The basic nutrients of concern in practical swine diets are crude protein, metabolizable energy, minerals, vitamins and water. Recommended allowances of these basic nutrients are in Tables 1 through 3 for each swine class. Average analyses of typical swine feedstuffs are given in Table 4.

Crude Protein

The crude protein requirement of a pig is usually determined as the amount of protein required in a corn-soybean meal diet to meet the animal's amino acid requirements. Since lysine is usually the first limiting amino acid, the amount of protein required is the level that meets the lysine requirement. By adding synthetic lysine, the amount of protein required may be decreased.

Substituting other sources of protein for the soybean meal may increase the protein requirement due to lower lysine levels. When using various sources of protein and amino acids, the amino acid content of the ingredients must be evaluated to insure that specific amino acid requirements are met.

Currently, most nutritionists agree that supplementation of corn diets with soybean meal provides amino acid levels for adequate and possibly optimal performance with a possible exception of starter diets. Combinations of several protein sources with soybean meal may provide a slightly more ideal balance of amino acids. Any improvement in performance, however, may be offset by higher feed costs and the inconvenience of storing and using several protein sources.

Tables 1 through 3 list the recommended allowances for protein plus five amino acids which may be limiting in common swine diets: lysine, methionine plus cystine, tryptophan and threonine.

Metabolizable Energy

The metabolizable energy (ME) in a swine feedstuff is that portion of the total gross energy which can be used by the pig for growth, lactation, maintenance of the body, movement and heat production. Metabolizable energy concentrations of feeds are expressed as kilocalories of ME per pound of feed. Efficient use of this energy depends on the level of other nutrients, especially protein.

Minerals

These minerals are the major ones of concern in typical swine diets for building bones and other important body functions:

calcium zinc
phosphorus copper
salt (sodium + chlorine) iodine
iron selenium
manganese -

At least 10 other minerals are required but are normally found at adequate levels in commonly used feedstuffs. A major concern in mineral nutrition is to select sources which provide adequate levels of the minerals in a readily available form. Evaluation of mineral sources is discussed in Extension Bulletin #856, Evaluating Alternative Swine Feeds.

Supplemental phosphorus is added to the diet mainly through defluorinated phosphates such as dicalcium phosphate and defluorinated rock phosphate. Desirable phosphorus sources are low in fluorine content and have a medium to fine particle size for thorough mixing in the diet.

Vitamins

These 11 vitamins are the major vitamins to be added to swine diets to promote normal body functions:

A pantothenic acid
D choline
E B12
K biotin
riboflavin folic acid
niacin -

All other vitamins that are required by the pig are generally found in commonly used feedstuffs or are produced in the pig at levels adequate for good performance. Biotin and folic acid may only be justified in breeding herd diets because of cost.

Storing vitamins in hot, humid conditions for extended periods of time may reduce potency or activity. Vitamin activity may be prolonged by avoiding storage with certain trace minerals, by gelatin encapsulation and by addition of antioxidants.

Most vitamin allowances (Tables 1-3) are expressed as amounts to be supplemented to the diet. Because of the uncertainty of levels of vitamins in grains and protein sources, it is advisable to disregard their contributions to vitamin needs. Supply the total vitamins needed as added or supplemented vitamins. Vitamin concentrations are reported in various ways but should be converted to I.U.s (International Units), mg (milligrams) or mcg (micrograms) of vitamin added per pound of final ration for comparison with the allowance levels in the tables. Conversion factors and a discussion of vitamin activity are found in Extension Bulletin #856, Evaluating Alternative Swine Feeds.

Water

Water is often neglected as a critical nutrient and must be supplied in unlimited amounts for optimum growth and performance. Feed intake may be reduced by low water consumption. Water requirements range from 7 to 20 pounds of water per 100 pounds of body weight depending on pig age and environmental conditions. Even with free access to automatic watering devices, low flow rates may cause inadequate water intakes.

Special Considerations in Each Production Phase

Although sound nutrition ideas apply to all phases of pork production, each phase has special dietary problems and nutritional needs. A complete life cycle feeding program is needed to reduce feed costs per pound of hog marketed.

Developing Gilts and Breeding Sows

Feed management for the developing replacement gilt and the open sow should maximize reproductive performance. Developing gilts should be fed to encourage growth of skeleton, muscle and general body size and to stimulate sexual maturity at an early age.

Select replacement gilts as early as possible (180-200 pounds) and limit feed intake to prevent over-conditioning. Excessive fatness or finish is wasteful and may lead to lowered reproductive performance. Generally five to six pounds of a grower diet will provide adequate nutrients. It is desirable to have gilts in a weight-gaining condition so as to encourage regular cycling, acceptable conception rates and large litter sizes. Breeding of gilts that are too small (under 250 pounds) or in poor body condition will often lead to rebreeding problems after weaning. Flushing gilts (at least six to eight pounds of feed per head per day) before breeding may improve litter size; however, feed intake must be reduced to about four pounds per head per day as breeding begins.

Most open sows have recently been weaned or have failed to conceive in a previous breeding period. Feed levels for these open sows should control body condition but put them in a weight gaining situation at breeding time.

Withholding feed from sows at weaning will not "reduce the flow of milk" and could have a detrimental effect on rebreeding. Open sows should receive four to six pounds of a quality gestation diet per day while in the breeding area. Extremely thin sows may require more feed to enhance rebreeding. If many sows become extremely thin due to heavy milk production, consider ways to increase feed intake during lactation. More frequent feeding or adding palatable ingredients to the diet may help. Adding fat to the lactation diet may also increase energy consumption. High levels of intake during gestation may further reduce lactation intake levels. If sows do not cycle or rebreed, consider culling the sow.

No special diet ingredients are necessary for breeding females. Adequate amounts of protein, calcium, phosphorus and vitamins are especially important for breeding success. Exercise extreme care to prevent use of moldy feedstuffs. Zearalenone, aflatoxins or other toxic substances produced by certain molds may negatively affect reproduction in the sow.

Bred Gilts and Sows

Mature bred sows require little more than a maintenance diet during the first 90 days of gestation. During the last 20-25 days of gestation, rapid growth of the developing litter demands extra nutrients. Gestation weight gain for mature sows need not be more than 30-60 pounds. Some producers prefer to maintain a constant daily feed allowance throughout gestation. Others increase feed amounts as gestation progresses. Research demonstrates that either method can be successful if the total gestation feed allowance supplies adequate nutrients.

Bred gilts require feed nutrients for maintenance, growth of the developing litter and additional body growth of the gilt herself. Assuming proper body condition at breeding, gilts should gain about 75 pounds during the first gestation. Inadequate nutrition at this time frequently leads to problems in rebreeding the first litter sows.

The amount of feed intake during gestation will depend on sow productivity, type of housing, energy concentration of the diet and season of the year. Typical corn-soybean meal diets fed at four pounds per head per day will supply adequate energy to maintain the average sow in acceptable body condition. Diets containing higher fiber levels (including oats, barley, alfalfa, etc.) may be required in slightly higher amounts.

Sows kept in group pens or individual stalls get less exercise and are generally not exposed to as much cold weather as sows kept on pasture or in outside lots. Therefore, the bred sow requires less feed energy when confined. Total feed intake may vary from three to four pounds per day for individually penned sows in summer to six pounds for sows in outside lots during winter.

The adequacy of feed intake over the reproductive cycle of a sow can be evaluated by the degree of condition or body fat levels. This can be measured as backfat, fatness over the hook or aitch bone and general body shape. Sows that have at least .7 inches of fat at the last rib probably have adequate condition to enter a normal lactation period if sufficient lactation diet is consumed. Also the hook bones or point of the hip can be felt with the finger tips to estimate condition. This bone can barely be felt if the desired level of finish is covering it. The sow's body as viewed from the rear should show a general oval shape.

A sow's daily feed intake during gestation will vary widely according to the factors discussed earlier. Therefore, the concentrations of protein, minerals and vitamins must also vary in order to supply the sow's daily needs. For example, a gestating sow receiving six pounds of feed per day would only require a calcium level of .60 percent to supply the 16.3 grams of calcium needed daily. But a sow fed three and one-half pounds daily would require 1.03 percent calcium in the ration.

Fat added to sow diets during the final seven to 10 days before farrowing may increase the survival of baby pigs shortly after farrowing. If the survival rate of pigs born alive is under 90 percent, addition of 80 to 100 pounds of fat per ton of sow diet may provide an economical boost to litter size and weight at weaning. Increasing total intake of a standard sow diet without added fat during this same period may also improve survival.

Farrowing and Lactating (Milk-Producing) Sows

The farrowing house diet should provide increased nutrients for milk production, prevent constipation and prevent excessive weight losses. From gestation to full lactation, the sow's total energy requirements may double or triple. Although the sow can use nutrients stored in her body to produce milk, inade-quate feed intake will often result in lowered milk production; smaller, weaker pigs; and rebreeding problems. A sow must consume at least 10-14 pounds of a standard lactation diet daily (14000-19000 kcal of metabolizable energy) to maintain adequate milk production and body condition. Sows with large litters (10 pigs or more) may require as much as 16-18 pounds and peak intake may be over 20 pounds per day. Feed intake must be carefully monitored in lactating sows since low consumption levels may indicate sickness, constipation or heat stress in the sow. Corrective action must come rapidly to avert milking problems and litter losses.

A program of controlled feed intake yields the best results. On the day of farrowing, sows may have little or no appetite; however, offer them about three pounds of lactation diet. Thereafter, sows should receive two to three additional pounds per day so that they are consuming 12 or more pounds daily by five to six days after farrowing.

Excessive weight losses in sows and gilts are often associated with slow returns to heat, non-returns or poor conception rates following weaning. Problems are more common in first litter gilts, high milk-producing sows, longer lactation periods or when high-fiber, low-energy diets are involved. Check feed intake levels, estimate daily nutrient intake and correct feeding shortages. More frequent feeding, reduced bulkiness and/or fat addition may be necessary to prevent excessive weight losses and to meet daily nutrient needs (Table 1).

Constipation occurs in a large percentage of the sows farrowed and often goes undetected. This reduction in feed passage results in lowered feed intake and reduced milk production. Proper use of mineral laxatives in lactation diets will generally reduce constipation with little reduction of the dietary energy concentration. Potassium chloride at 15 to 20 pounds per ton is an economical, effective laxative that can be safely fed through four weeks of lactation. Epsom salts (magnesium sulfate) at 20 pounds per ton is a possible alternative.

Bulky fibrous feedstuffs exert a mild laxative effect on the sow. Psyllium seed or husks (20 pounds per ton) appear to be one of the most effective laxatives tested in the sow. Wheat bran added at 10-25 percent of the diet or addition of oats, barley, beet pulp, linseed meal or alfalfa meal have been used depending on their availability and cost. However, these bulky feedstuffs lower the energy concentration of the ration, which may limit milk production. Fiber may also increase the heat of digestion in the sow, adding to heat stress problems in summer. Addition of fat to the diet may also produce a laxative effect on the sow.

Nursing Pigs

A practical goal for feeding the nursing pig is to make maximum use of milk yet teach young pigs how to eat dry food. A high milk-producing sow will provide essentially all the nutrients (except iron) needed for excellent pig growth up to three weeks of age. At that point, the sow's milk production levels off or begins to decrease and the pig's needs continue to increase. It normally takes about 4 1/2 pounds of milk for each pound of litter gain. After three weeks of age, pigs should begin to consume enough creep feed to improve weaning weights and post-weaning growth.

Creep feed consumption is dependent on the palatability of the diet. Use every possible means to keep the creep feed fresh. Buy or mix creep diets often and feed in small, shallow trays once or twice daily. Large capacity self-feeders must be managed well to prevent creep feeding problems. Prevent contamination with manure and urine and fill with no more than one day's feed supply.

The creep diet may be a 24 percent crude protein prestarter or a lower cost, 20 percent starter. Limited amounts of porcine plasma, fish meal, sugar, fats, whole dried whey, soy concentrates or isolates, rolled oat groats or other special ingredients may improve palatability and quality of the ration. However, it should be noted that more complex, higher cost diets may result in more expensive weight gains than simple corn-soybean meal based feeds. The physical form or texture of the creep diet affects acceptability to the baby pig. Hard, large-size pellets or dusty meal-type diets are usually not eaten as well as small, soft-pelleted or crumble-textured feeds.

The decision to purchase the prestarter and starter diets or mix them on the farm depends on comparative costs, desired quality of end products and availability of ingredients. These diets are relatively expensive on a per weight basis but the volume used should be small compared to other diets. An important profit opportunity lies in preventing waste of these expensive feeds.

Weaned Nursery Pigs

This production phase is frequently hampered by inadequate housing, management and nutrition. Under these conditions, the pigs usually go through a period of little or no growth for seven to 14 days after weaning (post-weaning lag). With proper nutrition, the set-back suffered by the pigs can be reduced.

Good nutritional management includes feeding a diet containing high quality, highly palatable ingredients with the proper nutrient levels and proper feeding methods. The type of diet required depends on the age and weight at weaning. The younger and/or smaller the pig at weaning, the more critical the diet becomes. Dried whole whey, fish meal, porcine plasma, dried whole blood, soy protein concentrates or isolates and blends of these products are digestible sources of important nutrients. Higher levels of these ingredients are more important in the diets of pigs weaned at 14 days of age than pigs weaned at 21 to 28 days. Pigs weaned at 35 days or more only need this type of diet for three to five days after weaning. Other ingredients, such as organic acids, bentonite, fat, etc., may be justified to improve performance at weaning.

If pigs have learned to eat a creep diet before weaning, that same diet used in the nursery will encourage the pig to eat and will reduce the post-weaning lag. Pigs weaned at an early age tend to feed all at once, just as they nursed the sow. Provide adequate feed trough space (4 inches per pig or two pigs per hole) for all pigs. Do not allow pigs to over-eat. Their digestive systems will be overloaded, possibly causing scouring and death. Start pigs out on a slightly limited feed supply. Hand feed two to four times a day to gradually increase feed intake.

With proper nutrition, the effect of inadequate housing and management can be partially overcome. For more information concerning the proper management and nutrition of weaned pigs, see Extension Bulletin #871, Management of Young Pigs.

Growing-finishing Pigs

This phase of production involves the major feed consumption stage and offers the greatest opportunity for improving feed efficiency and savings. The major feeding decisions involve selecting the most economical protein levels and energy sources and maintaining a proper calcium-phosphorus balance. The goal is to reduce feed costs per pound of gain while maintaining rapid daily gains and acceptable carcass quality.

The nutrient requirements for the "average" pig are well established and are provided in Table 2. Using these specifications we can develop diets which will produce good performance in "average" pigs. However, when feeding a pig that has superior genetic capabilities for growth of lean tissues, the requirements for nutrients may increase very dramatically.

In addition to genetic lean gain capability, daily feed intake greatly affects feeding growing-finishing hogs. Daily feed intake may be affected by energy density of the diet, sex, genetics, environmental temperature, disease, palatability and other factors. As daily feed intake declines, the concentration of nutrients in the diet should be increased to meet the pigs' needs.

The growing-finishing pig can be fed alternate energy sources such as grain sorghum, barley, wheat, triticale, fat and a variety of by-product feedstuffs. Decisions to change diets from the typical corn-soybean meal based feeds depends on comparative costs of gain, availability of alternative feeds, effects on carcass quality and special feed handling considerations. The growing-finishing pig can quickly adapt to new feedstuffs with minimum setback.

Much research information is available on the most common energy sources which are alternatives to corn. Barley and wheat are two Georgia-grown grains which may be priced competitively to corn during the harvest season. Grain sorghum can be an excellent alternative to corn; however, sorghum varieties vary widely in quality, protein level and protein digestibility and should be analyzed before use. Although triticale is a relatively new grain that can also be an excellent alternative to corn, its energy content may be slightly below that of corn. Some energy alternatives such as wheat must receive special processing before use in swine diets.

The addition of fat to grower-finisher diets should depend on the relative costs of fat and grain plus other factors such as fat handling capabilities and environmental temperatures. If fat is 15 cents per pound and corn is $4 a bushel, then fat could be economically included at levels up to 11 percent of the diet. If eight percent or more fat is added, feed-handling problems will be encountered in conven-tional mixing equipment.

Fat added to the diet increases the energy concentration (kcal/lb). Pigs on full feed will eat to meet their energy requirement. Adding fat generally reduces the pounds of feed consumed per day. Therefore, the concentrations of protein (amino acids), minerals and other nutrients should be increased in proportion to the energy. Adding fat alone to the diet should improve feed conversion but may also increase backfat. Increasing the levels of other nutrients proportionally may also improve pig gains and can result in lower backfat. Adding fat is especially important during periods of high temperatures, when feed intake and therefore gain are normally reduced. Increasing the energy density of the diet by adding fat allows growing-finishing pigs to consume adequate energy even though they are eating less feed. If you intend to add three percent or more fat to growing-finishing diets, check with a swine nutritionist on levels of other nutrients required to make best use of the extra energy.

A growing list of by-products such as whole cooked soybeans is being fed to growing-finishing hogs. The economic feasibility for use of each by-product must be carefully justified. Some by-products will not support adequate growth to justify special transportation and feed-handling costs.

Combining Ingredients to Meet Nutrient Needs

To properly formulate a diet for a particular class of pigs, you must know:

Nutrient Requirements and Limitations

To formulate a swine diet, first determine the nutrient requirements for the animals to be fed. First, decide the weight or class of swine to be fed. Next, find the nutrient requirements in Table 2 or Table 3. The primary concern in formulating a diet is meeting the animal's minimum nutrient requirements. However, several nutrients can cause problems when included at high levels. The level of calcium in the diet should not exceed 1.5 times the phosphorus level. Higher levels will result in poorer feed conversion and possibly reduced gains. High levels of salt will reduce feed intake. Salt should not exceed .5 percent of the diet. Increased fiber in the diet generally means lower energy content. Fiber should not exceed five percent of the diet for all classes of hogs except possibly gestating sows.

Ingredients and Ingredient Limitations

Once you know the nutrient requirements, select the ingredients. Ingredients can be divided into categories based on the specific function: energy sources, amino acid sources, mineral sources, vitamin sources and additives. Grain is the primary source of energy in swine feeds while oilseed meals and animal by-products are the primary sources of amino acids. In most Georgia swine diets, a commercial product (supplement or basemix) is the source of minerals and vitamins. Formulating a diet containing a complete supplement is easy. Follow feed tag directions. Complete supplements are specifically designed to be fed at the levels described on the tag. Adding a different amount to the feed can cause nutritional problems and increase the cost of production. If commercial basemixes are used, the amount of basemix added to a ton of feed should be the amount listed in the feeding instructions. Corn is the traditional energy source in swine diets. Soybean meal is the primary protein source. There are excellent alternatives to both ingredients available to Georgia swine producers. These alternatives are discussed in detail in Evaluating Alternative Swine Feeds, Extension Bulletin #856. Table 5 contains a list of possible feed ingredients and their limitations.

Batch size

The batch size is the amount of feed to be mixed at one time. When balancing a swine diet, most producers use a batch size of one to three tons. Using a batch size of 100 pounds results in a percentage formula (for example; 80 percent corn, 20 percent supplement). This simplifies the calculating and makes adjusting for various batch sizes easier. Most feeding instructions for commercial products are given on a ton basis. Since most commercial feed mills have a two or three ton capacity, formulating a diet on a ton basis allows for simple conversion to two or three ton batches.

Formulating Swine Diets

Three basic methods are used to formulate swine diets: Pearson square, algebraic equations and linear programs (computer). The Pearson square is fairly simple to use when the number of ingredients is limited. It is covered in detail in Principles of Balancing a Ration, Pork Industry Handbook Factsheet 7. The use of algebraic equations requires some knowledge of algebra. However, this method is much more flexible than the Pearson square. Most diets are now formulated using computers. Microcomputer programs are now available that will balance a diet for many nutrients and assist with economic decisions.

Algebraic method. Basic algebra can be used to balance a swine diet by solving two or more algebraic equations simultaneously. For example, a single equation can be used to calculate the amount of corn and soybean meal needed to meet a finishing hog's requirement for lysine. Other equations can be solved simultaneously to balance the same diet for lysine, calcium, phosphorus and other nutrients.

To balance a diet for one nutrient using two ingredients, the following equations are used:

a) X + Y = batch size
(X = amount of ingredient 1 and Y = amount of ingredient 2)

b) X * (% nutrient in ingredient 1) + Y * (% nutrient in ingredient 2) = amount of nutrient desired per batch

Equation (a) is solved for Y as follows:

c) Y = batch size - X

The two equations are now combined by inserting this value of Y into equation b:

d) X * (% nutrient in ingredient 1) + (batch size - X) * (% nutrient in ingredient 2) = amount of nutrient desired/ batch

Solving this equation for X will give you the amount of ingredient 1. Inserting the value of X into equation c will give you the amount of ingredient 2.

When using this new equation (d), the diet can be formulated for only one nutrient. If the lysine content of all ingredients are known, the diet should be balanced for lysine. Otherwise, use crude protein. Usually, one ingredient is used to supply minerals and vitamins (basemix or supplement). If a basemix is used, the amount to be added is fixed. Fixed ingredients are those that are added at a set amount. The amount of specialty ingredients such as whey, fish meal, growth promoters, etc. are usually fixed as well. The best way to learn this method is to work through examples. The following example shows the use of the algebraic method of formulation. We will formulate a diet for pigs weighing 110 pounds to market. In Example 1, corn, soybean meal (solvent, hulled) and a commercial basemix are used. Since we know what animals we are feeding and the ingredients to be used, we must first determine the nutrient requirements. The nutrient requirements for these pigs are found in Table 2. A diet for finishing pigs should contain 13 percent protein, .65 percent lysine, .60 percent calcium and .50 percent phosphorus. In this example we will balance the diet for lysine. The nutrient content of all ingredients except the basemix is found in Table 4. The nutrient content of a commercial basemix is found in the "Guaranteed Analysis" on the feed tag. For these examples, the basemix contains no protein, lysine or metabolizable energy. It does contain 21.7 percent calcium, 8.6 percent phosphorus, 14 percent salt and all the vitamins and trace minerals required. It is designed to be fed at 50 pounds per ton or 2.5 percent of the total diet. The batch size for this example is 2000 pounds.

Example 1.

a) X + Y = batch size - base mix = 2000 lb - 50 lb = 1950 lb
(X = amount of soy bean meal and Y = amount of corn)

b) X * (% lysine in soybean meal) + Y * (% lysine in corn) = amount of lysine desired per batch
X * (.032) + Y * (.0024) = (2000 lb * .0065)

c) Y = 1950 lb - X

d) X * (.032) + (1950 lb - X) * (.0024) = (2000 lb * .0065)
.032 X + 4.68 lb - .0024 X = 13 lb
.0296 X = 8.32 lb
X = 281 lb soybean meal

e) Y = 1950 lb - 281 lb = 1669 lb corn

Finally, check the formula to make sure the requirements are met. Tables 6 and 7 contain a worksheet designed to simplify this step and to provide a guide for formulating the diet.

Computer formulation. The main reasons for using a computer to formulate swine diets are speed and accuracy. Computer formulation programs can complete many calculations in a short period of time with a high degree of accuracy. You can formulate the same diets using the algebraic method, but the time required would make it impractical. Using the computer, many optional ingredients and numerous animal nutrient requirements can be considered all at once. Ingredient prices can be considered and special limitations can be placed on the levels of nutrients and ingredients.

The computer uses a method called linear programming to find the solution to many equations at one time. This is a more complicated version of the algebraic method discussed earlier. The final diet calculated using this method is a combination of ingredients that meet the nutrient requirements of the animal at the least cost per pound of feed.

It is important to remember that a least cost diet may or may not produce the most economical animal performance. A least cost diet may meet the nutritional requirements but be so unpalatable that the animal will not eat it. Computer formulation requires that you have a working knowledge of swine nutrition and feed management. Common sense will also help you evaluate a diet formulation provided by the computer. Two major differences exist between computer formulation and other methods. With other methods, you are trying to get a minimum amount of one or more nutrients in the feed. Computer formulation allows you to set minimum, maximum and equality limits on nutrients and ingredients. A minimum restriction means that you want at least a particular level of a nutrient or ingredient in the formula. Table 2 shows that a pig weighing 110 pounds to market requires 13 percent protein. You would set a minimum restriction for protein to insure you get at least 13 percent protein in the feed. A maximum restriction means you want no more than a particular level of a nutrient or ingredient in a formula. An equality means that you want exactly a set level of nutrient or ingredient in the diet.

Another important difference is the information usually supplied by a computer formulation. Like other methods, you will get the amount of each ingredient in the formula and the nutrient content. Computer program output usually provides valuable economic information as well. For each ingredient used, the program can calculate the price range in which the ingredient will be economical. For ingredients that are not used, most programs will calculate the price at which they would have been used. These are often called "in prices", "shadow prices" or "opportunity prices." Some programs will also determine the effect that changing a nutrient or ingredient restriction will have on the cost of the feed. These values can help you make the best use of ingredients that you have and also assist with purchasing ingredients.

Computer formulation, like all other methods of formulation, requires the use of accurate, representative feed composition values and the correct swine nutrient requirements. A standard set of feed composition values is available with most formulation programs. These can be modified to reflect the actual content of your ingredients. A chemical analysis of your ingredients will provide the most accurate feed formula. The most important point to remember about computer feed formulation is that the final formula is only as good as the information you provide the program. Additional information about computer formulation in general and the UGA FEEDER Series of microcomputer formulation programs is found in the Extension miscellaneous publication #201 "Microcomputer Use in Livestock Feeding" available in most county Extension offices.

Common Problems in Georgia Swine Rations

Feed analysis data from the University and State laboratories indicate that the most common detectable problems in Georgia swine diets are:

The high calcium levels may stem from excessive calcium in soybean meal (calcium carbonate added as a drying agent) or complete protein supplements and basemixes. The low phosphorus levels are usually due to inadequate supplementation of this relatively expensive mineral. Low protein levels in mixed diets may result from formulation errors or poor protein sources. Tabular values for protein levels in grains and protein sources often over-estimate true values. To solve these problems:

Table 1. Daily Nutrient Allowances of Breeding Swine
Nutrient Sows and Gilts Boars
Gestation Lactation1
Metabolizable energy, kcal 5,7002 17,5703 7,000
Protein, g 236 763 318
Lysine, g 9.1 40.0 13.6
Methionine + cystine, g 5.8 24 8.1
Tryptophan, g 1.6 7.8 2.7
Threonine, g 6.4 28 10.0
Calcium, g 16.3 40.9 20.4
Phosphorus, g 13.6 32.7 17.0
Salt, g 6.4 19.1 7.9
Iron, mg 144 432 180
Copper, mg 10.8 32.4 13.5
Manganese, mg 56 168 70
Zinc, mg 120 360 150
Iodine, mg .4 1.2 0.5
Selenium, mg4 -- -- --
Vitamin A, IU 12,000 36,000 15,000
Vitamin D, IU 1,200 3,600 1,500
Vitamin E, IU 50 150 62.5
Vitamin K, mg 4 12 5
Riboflavin, mg 8 24 10
Niacin, mg 48 144 60
Pantothenic acid, mg 40 120 50
Choline, mg 1,600 4,800 2,000
Vitamin B12, mcg 40 120 50
Biotin, mg .24 .72 0.30
Folic acid, mg 1.8 5.4 2.25
Feed required, lb 4 12 5

1 To determine the requirement as a percentage or amount/lb of diet, use the following formulas:

g/day to %: (daily requirement/454)/daily feed intake, lb/day x 100 =%

mg/day to mg/lb: daily requirement/daily feed intake, lb/day=mg/lb

IU/day to IU/lb: daily requirement/daily feed intake, lb/day=IU/lb

2 Research has shown that increasing daily energy intake during the last 10-30 days of gestation may improve birth weights and pig survival. Daily energy intake should be increased 718-2700 kcal/day depending on pig weights and survival.

3 Daily energy needs depend on level of production. This level of energy is adequate for a sow nursing 8 pigs. Daily energy intake should increase 1500 kcal for each pig over 8.

4 The maximum level of selenium allowed by FDA is subject to change. Check current feed regulations.

Table 2. Nutrient Allowances of Starting, Growing and Finishing Swine
Percentage or Amount per pound of Diet
- Liveweight class, lb
Nutrient < 151 15-202 20-40 40-110 110-mkt.
Metabolize energy, kcal 1,500 1,500 1,500 1,400 1,400
Protein, % 24 20 18 15 13
Lysine, % 1.40 1.25 1.15 .80 .65
Methionine + cystine, % .77 .69 .63 .45 .37
Tryptophan, % .22 .20 .18 .13 .11
Threonine, % .90 .80 .74 .53 .44
Calcium, % .95 .90 .85 .65 .60
Phosphorus, % .80 .75 .70 .55 .50
Salt, %3 .35 .35 .35 .35 .35
Iron, mg 45 45 45 36 36
Copper, mg4 3.4 3.4 3.4 2.7 2.7
Manganese, mg 14.0 14.0 14.0 14.0 14.0
Zinc, mg 45.0 45.0 45.0 36.0 36.0
Iodine, mg 0.1 0.1 0.1 0.1 0.1
Selenium, mg4 0.045 0.045 0.045 0.045 0.045
Vitamin A, IU 3,000 3,000 2,500 1,500 1,500
Vitamin D, IU 300 300 250 150 150
Vitamin E, IU 10 10 10 8 8
Vitamin K, mg 1 1 1 1 1
Riboflavin, mg 2.5 2.25 2.0 1.4 1.2
Niacin, mg 12 12 10 8 8
Pantothenic acid, mg 8 8 8 7 6
Choline, mg 600 600 600 400 300
Vitamin B12, mcg 10 10 10 6 6

1Pigs weaned at less than 28 days of age. This diet should contain 25-75% milk products.

2This diet should contain 5-25% milk products.

3When adding large amounts of dried whey (10% or more), the added salt should be reduced (.25%) due to the high salt content of some whey products.

4Addition of 57-114 mg/lb of copper from copper sulphate has been shown to improve performance of young pigs (up to 40 lbs).

5The maximum level of selenium allowed by FDA is subject to change. Check current feed regulations.


Table 3. Nutrient Allowances of Breeding Swine
Percentage or Amount per Pound of Diet
Nutrient Sows and gilts Boars
Gestation Lactation1
Metabolize energy, kcal 1,400 1,400 1,400
Protein, % 13 14 14
Lysine, % .50 .80 .60
Menthionine + cystine, % .32 .44 .36
Tryptophan, % .09 .14 .12
Threonine, % .35 .51 .44
Calcium, % .90 .75 .90
Phosphorus, % .75 .60 .75
Salt, % .35 .35 .35
Iron, mg 36 36 36
Copper, mg 2.7 2.7 2.7
Manganese, mg 14 14 14
Zinc, mg 30 30 30
Iodine, mg 0.1 0.1 0.1
Selenium, mg2 0.045 0.045 0.045
Vitamin A, IU 3000 3000 3000
Vitamin D, IU 300 300 300
Vitamin E, IU 12.5 12.5 12.5
Vitamin K, mg 1 1 1
Riboflavin, mg 2 2 2
Niacin, mg 12 12 12
Pantothenic acid, mg 10 10 10
Choline, mg 400 400 400
Vitamin B12, mcg 10 10 10
Biotin, mg 0.06 0.06 0.06
Folic acid, mg 0.45 0.45 0.45

1The nutrient requirement of lactating sows increases as feed intake decreases. The nutrient content should be increased 8.3% for each pound below 12. (If sows will only consume 10 lb/day, the levels of required nurients should be increased 16.6%.)

2The maximum level of selenium allowed by FDA is subject to change. Check current feed regulations.


Table 4. Average Analysis of Ingredients Used in Swine Diets1
Ingredient Metabolizable energy Protein Calcium Phosphorus Fat Fiber Lysine Methionine & cystine Tryptophan Threonine
kcal/lb percent
Alfalfa meal (dehydrated) 600 17.5 1.40 .26 3.2 23.5 .80 .58 .36 .70
Animal fat 3,590 -- -- -- 99.4 -- -- -- -- --
Barley 1,275 11.5 .06 .36 1.8 7 .36 .37 .16 .42
Blood meal 1,200 80 .28 .22 1 1 5.37 2.44 1.02 4.90
Calcium carbonate (limestone) -- -- 38.00 -- -- -- -- -- -- --
Corn (yellow) 1,500 8.2 .01 .24 3.6 2.2 .24 .39 .09 .39
Cottonseed meal (solvent) 1,100 41.7 .20 1.00 2.7 13.4 1.55 1.14 .48 1.32
Defluorinated phosphate -- -- 32.00 18.00 -- -- -- -- -- --
Dicalcium phosphate -- -- 20.00 18.50 -- -- -- -- -- --
Distillers dried grains & solubles, corn 1,270 27 .35 .95 8.0 8.5 .60 1.00 .20 .92
Fish meal (menhaden) 1,200 61.5 5.10 2.98 9.7 .7 4.60 2.50 .71 2.50
Grain sorghum (milo) 1,425 9.8 .02 .27 3.0 2.8 .22 .31 .09 .27
Meat & bone meal 1,100 50.6 8.90 3.93 10.8 2.4 2.50 1.27 .29 1.50
Molasses, cane 1,060 3 .50 .05 -- -- -- -- -- --
Oats 1,200 12 .10 .33 4.0 12.0 .40 .33 .13 .16
Oat groats 1,450 15.8 .08 .43 6.2 2.5 .45 .46 .18 .20
Peanut meal 1,375 52.3 .15 .55 4.1 6.0 1.78 1.26 .55 .49
Rye 1,230 12.6 .08 .30 1.8 2.8 .40 .36 .14 .86
Skim milk, dried 1,545 33 1.25 1.00 .5 -- 2.70 1.20 .45 1.60
Soybean meal (solvent, hulled) 1,520 49.2 .40 .65 1.5 3.3 3.20 1.55 .63 1.92
Soybean meal (solvent) 1,475 45.6 .50 .71 2.1 5.9 2.88 1.22 .55 1.81
Soybeans (whole cooked) 1,600 38 .25 .58 18.0 5.0 2.40 1.05 .55 1.50
Sunflower meal (extracted w/hulls) 1,044 28.7 .38 .97 2.7 24.8 1.47 2.00 .52 2.13
Meat meal tankage 1,020 59.5 5.80 2.99 9.0 2.2 3.73 1.19 .72 2.39
Triticale 1,475 11.8 .05 .30 1.8 2.9 .43 .60 .13 .41
Wheat (soft winter) 1,500 11.9 .01 .22 1.7 2.8 .35 .34 .12 .32
Wheat bran 890 15.0 .14 1.10 4.1 11.0 .50 .27 .27 .42
Wheat middlings 910 17.1 .10 .88 4.4 7.9 .60 .31 .20 .49
Whey (dried) 1,445 12 .90 .80 .5 -- .80 .40 .13 .89
Whey (low lactose dried) 1,250 17.0 1.50 1.20 1.0 -- 1.47 1.14 .36 .50

1Standard reference values modified to reflect Georgia feedstuffs.


Table 5. Maximum Levels of Ingredients for Swine Diets
Maximum level % in complete feed
Ingredient Starter Grower-Finisher Gestation Lactation Remarks
Alfalfa meal-dehydrated 0 5 50 10 A
Animal fat 5 8 8 8 B
Barley 0 80 80 50 C
Blood Meal 5 5 5 5 D
Cottonseed meal 0 5-10 5 5 E
Meat and bone meal 0 5 10 10 D
Oats 10 20 70 15 C
Peanut meal 0 5 5 5 F
Rye 0 20 20 20 G
Tankage 0 5 5 5 D
Wheat bran 0 0 30 10 C
Wheat middlings 5 10 30 10 C


A. High fiber, low energy but high in B vitamins.

B. High energy, but can cause feed handling problems when over 8% of the diet.

C. Low energy, high fiber (7-12% crude fiber).

D. High protein, but can reduce palatability of the diet.

E. Low lysine compared to soybean meal; contains gossypol, which is toxic to swine. Can replace up to 50% of the protein from soybean meal.

F. Low in lysine and methionine; can replace up to 50% of the protein from soybean meal.

G. Low energy, high fiber, can reduce palatability of swine diets.

Table 6. Swine Diet Formulation Worksheet, Part 1
Description of the diet:
Animal Requirements
Metabolizable energy, Kcal/lb - Crude protein, % -
Calcium, % - Phosphorus, % -
Lysine, % - Salt, % -
Ingredient Nutrient Levels
Ingredient M.E. Protein Calcium Phosphorus Lysine Salt
kcal/lb % % % % %
____________ ____________ ____________ ____________ ____________ ____________ ____________
____________ ____________ ____________ ____________ ____________ ____________ ____________
____________ ____________ ____________ ____________ ____________ ____________ ____________
____________ ____________ ____________ ____________ ____________ ____________ ____________
____________ ____________ ____________ ____________ ____________ ____________ ____________
____________ ____________ ____________ ____________ ____________ ____________ ____________
____________ ____________ ____________ ____________ ____________ ____________ ____________
Diet Formulation
.
Go to Part 2 of the worksheet to check your formula.


Table 7. Swine Diet Formulation Worksheet, Part 2.
Ingredient - - - - - - - M.E. - - - - - - - -Protein- - - Lysine- - Calcium - Phos - - - Salt - -
amt/batch kcal/lb kcal % lb % lb % lb % lb % lb
____________________ _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
____________________ _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
____________________ _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
____________________ _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
____________________ _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
____________________ _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
____________________ _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
____________________ _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
Total _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
% or amt/lb _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
Requirement _______ ____ ____ ____ ___ ___ ___ ___ ___ ___ ___ ___ ___
If the % or amount/pound is less than the required amount, check your calculations one more time. If the % or amound/pound is equal to or greater than the required amount, you have successfully formulated a swine diet.


Bulletin 854/Revised May, 1995

The University of Georgia and Ft. Valley State College, the U.S. Department of Agriculture and counties of the state cooperating. The Cooperative Extension Service offers educational programs, assistance and materials to all people without regard to race, color, national origin, age, sex or disability.

An Equal Opportunity Employer/Affirmative Action Organization Committed to a Diverse Work Force

Issued in furtherance of Cooperative Extension work, Acts of May 18 and June 30, 1914, The University of Georgia College of Agricultural and Environmental Sciences and the U.S. Department of Agriculture cooperating.

Gale A. Buchanan, Dean and Director