Swine Diets


Originally published as PIH-23.

Allen F. Harper, Virginia Tech;
Richard D. Coffey, University of Kentucky;
Gilbert R. Hollis, University of Illinois;
Don C. Mahan, The Ohio State University;
J. Scott Radcliffe, Purdue University

Tom Carr, University of Illinois;
Palmer Holden, Iowa State University;
Tom Socha, North Dakota State University

Since the 1980’s, swine production has undergone tremendous changes related primarily to increasing size, specialization, and efficiency of individual production units. However, one factor has remained constant. Approximately 55-65% of production cost is attributed to feed costs. Considering this, it is apparent that utilization of properly formulated diets has a direct bearing on profitability in any swine production enterprise. This publication provides examples of properly formulated swine diets for various classes of swine. Commonly available feedstuffs were used in these formulations, but other grains and protein sources are available and can be effectively substituted. Each swine production unit is unique and the diet formulations provided may not apply directly to every farm situation. Producers and managers are therefore encouraged to consult with an animal nutritionist, extension specialist, or swine feed company technical representative to determine the most appropriate swine diet formulations for their farms.

Swine Nutritional Requirements

Proper diet formulation begins with accurate knowledge of the nutritional requirements of the pigs being fed. It is recognized that pig genotype and production classification have a major bearing on nutritional requirements. Factors that affect voluntary feed consumption also may have a bearing on dietary nutrient requirements.

For example, diets with greater energy concentration such as those with added fat may be consumed in lower quantities than diets with lower energy concentration. This can result in improved feed efficiency, assuming that nutrients in the formulation are adequate. In addition, high environmental temperatures can reduce feed consumption and alter diet formulation needs. The Nutrient Requirements of Swine, published by the National Research Council (NRC, 1998), provides reliable estimates of nutritional requirements for differing genetic and production classes of pigs and environmental conditions. Table 1 gives NRC (1998) suggested nutrient allowances for the most limiting essential amino acids, calcium, and phosphorus (total and available) for the diet formulations in this publication.

Composition of Feed Ingredients

The other key component of proper diet formulation is reliable information on the nutrient and energy composition of available feed ingredients. Table 2 provides typical nutrient and metabolizable energy content of feed grains, oil-seed meals, and various byproducts used in this fact sheet. Using reliable ingredient composition data, the feed formulator can determine the correct blend of ingredients to meet a specified set of nutrient requirements. In most cases, a computer program is used to formulate optimal diets based on nutritional value, cost, performance, and availability of ingredients. Limits can be set on the inclusion rate of certain ingredients based on their physical and chemical characteristics. For example, the inclusion rate of high fiber and low energy ingredients may be limited for growing pigs and lactating sows where high energy consumption is important. The upper limit of supplemental fat for diets in this fact sheet was set at 5% because excessively high fat levels can make the finished feeds more difficult to handle.
Compositions of several calcium and phosphorus supplements are presented in Table 3. Limestone (calcium carbonate) and dicalcium phosphate were used as supplements in the formulations for this publication; but cost, availability, or other factors may indicate that other sources are more appropriate. If other sources are substituted diet reformulation is necessary because different sources contain different levels of these important macro-minerals and, in some cases, different phosphorus availabilities.

Sow Diets

Diets 1 through 9 in Table 4 are to be limit fed to gestating gilts and sows. Emphasis has been placed on traditional corn-soybean meal based diets but formulations including a proportion of barley or wheat have been included. Daily feeding rates range from 4-6lb per sow, but the specific amount fed to individual animals should vary according to sow age, weight, housing-environment
and body condition. Focus should be on proper gestation weight gain (60-85lb for sows, 75-100lb for gilts) and maintenance of a “medium” body condition. Sows that are allowed to gain excessive weight and body condition during gestation usually experience lower feed consumption and greater weight loss during lactation.

Table 4 also includes three examples of “pre-farrowing” diets. These diets contain greater nutrient and energy density and are appropriate for sows in poor body condition, high producing sows, and mature sows during the final one to two weeks before farrowing. In place of a separate pre-farrowing diet, the lactation diet may also be fed to sows
in this category.

Table 5 provides lactation diets for sows nursing approximately 10 pigs growing at a moderate rate (~ .33lb/day). Table 6 provides similar diets formulated for higher producing (heavier milking) sows with approximately 10 pigs gaining about .44lb/day. Lactating sows should be encouraged to consume increasingly higher levels of lactation diet each day after farrowing and reach a high level of voluntary feed intake early in the nursing period. Indeed, a typical management challenge on breeding farms is getting high producing sows to consume at least 12lb of feed or more daily during lactation so that sow weight loss and rebreeding problems can be minimized. Maintaining proper ventilation and temperature in the farrowing room, well-designed and maintained sow feeders and waterers, and frequent feeding of a fresh, highquality diet all contribute to better feed consumption during lactation. During hot weather stress, the lactation diet examples with added fat are particularly appropriate because they provide greater energy and nutrient consumption by the lactating sow when voluntary feed intake tends to be low.

Breeder Boar Diets

With the exception of boar stud farms, most farms do not have a separate diet formulated for breeding boars. The sow lactation diets with moderate energy levels indicated in Table 5 would be adequate for sexually active boars assuming a minimum feeding rate of 4.5lb daily. Feeding rates of 5-6.5lb per day are common, and the actual amount fed is dependent on environmental temperature, body condition, age, and activity level of individual boars.

Weanling and Nursery Pig Diets

Weaning pigs at less than three weeks of age, coupled with multiple site production, has become commonplace in commercial swine production. Weanling pig performance can be quite good in these types of systems, but special attention to diet formulation and quality is critical for good results. Specialized diets with a complex set of ingredients are required for the early-weaned pig due to its immature digestive capacity and unique nutritional needs. A phase feeding program is particularly important for weanling and nursery pigs because as they grow rapidly, their nutritional needs also change rapidly. Phase feeding allows for good post-weaning performance and efficient conversion to less complex, lower cost diets based primarily on grain and soybean meal.

Table 7 provides examples of diets designed for segregated early-weaned (SEW) pigs weighing 12lb or less. It is apparent that these diets are very complex, containing only a limited amount of plant protein sources (soybean meal) and a variety of specialty ingredients that have proven to be effective in meeting the unique nutritional needs of the very young pig. Milk products and plasma protein products have been found to stimulate feed intake in earlyweaned pigs and have been included in all SEW and Phase I diets. In addition, SEW diets are typically fortified with synthetic lysine and methionine and have a feed grade antibiotic included. The antibiotic chosen is dependent on veterinary recommendations or on what products have proven most effective for weanling pigs in the given farm situation. Table 8 follows with a series of examples of three-phase starter diets for pigs weaned between 18 days and 21days and fed to an end weight of approximately 45 lbs. Like the SEW diets, the Phase I diets are quite complex and, therefore, are expensive to prepare and feed. Use of less expensive plant based (soy) protein products is increased in the Phase II diets; and, in the Phase III diets, soybean meal is the predominant protein source and lactose, dried skim milk or whey are reduced or eliminated.

Due to the complex nature of SEW and early-phase starter diets, many producers choose to purchase them as complete feeds direct from commercial mills. Another factor that contributes to this decision is that SEW and early-phase starter diets yield the best performance when fed in a crumble or small pellet form, and this equipment is generally not available on swine farms. Because SEW and Phase I feeds are very expensive, it is important to transition the pigs to the less expensive diets as they grow and become capable of digesting grain-soy based diets. In addition to proper diet formulation, getting early-weaned pigs off to a good start involves excellent sanitation, all-in, all-out nursery management, proper temperature and ventilation control and attention to detail to ensure that pigs adapt to the water and feeding equipment quickly.

Grower-Finisher Pig Diets

Most swine packing companies purchase market hogs based on carcass weight and lean meat content rather than simple live weight. The industry has adapted to this through increased use of lean genotype breeding animals and terminal mating systems for the production of high lean content market barrows and gilts. Consequently, the objective in diet formulation
for growing-finishing hogs is to optimize lean tissue growth rather than simply live weight gain.
To achieve optimum performance, high lean gain genotypes require diets formulated to contain higher nutrient and energy density. Gilts have slightly lower voluntary feed consumption and slightly greater lean tissue gain potential than barrows, particularly from about 110 lb body weight to market. Consequently, the nutritional needs of gilts and barrows differ. For this reason many production units formulate different diets for barrows and gilts and feed them separately. Phase feeding, in which diets are formulated specifically for weight and age classification of market hogs, is also a recommended practice.

Tables 9 through 18 provide diet formulation examples for grower-finisher hogs of various weight and sex categories with the assumption that lean tissue growth rate is approximately .72lb per
day from 45lb to market. Diet reformulation may be in order based on information from genetics suppliers or on-farm lean growth rate assessments. In addition, nutrient allowance adjustments may
be needed if certain performance modifiers are used in market hogs. For example, amino acid requirements are elevated when market hogs are fed diets containing ractopamine (Paylean®), which increases lean growth in market hogs.

Tables 9 through 13 provide several grower-finisher diets that utilize corn or grain sorghum as the grain source and regular or dehulled soybean meal as the primary protein supplement. Several of these diets contain supplemental fat for increased energy density (kcal/lb) in the diet. Tables 14
through 18 include diets formulated for similar classifications of grower-finisher hogs, but the examples include significant quantities of small grains, by-product feeds, or full-fat soybeans (cooked) in the formulations. When higher fiber and lower energy ingredients are included in the formulation, dietary energy density may be substantially reduced. As illustrated in the examples, this can be partly compensated for by setting a limit on the quantity of lower energy ingredients included in the diet and by adding supplemental fat to the diet.

Vitamins and Trace Minerals

The formulations for the vitamin premix and sow vitamin add pack used in these diet examples are presented in Table 19 and include the amount of vitamin activity per lb of premix and the suggested form of each vitamin. This premix is designed to provide proper vitamin supplementation when thoroughly mixed into the diet at specified rates for each pig classification. It is recommended that swine vitamin premixes be purchased from a commercial company as they have superior mixing and quality control conditions for preparation of micro-ingredient premixes. Because most vitamin compounds in a premix are subject to oxidation and degradation, it is recommended that vitamin premixes be stored in a cool, dry place and used within three months of purchase. If combination vitamin-trace mineral premix products are used, vitamin storage life is reduced to about one month because trace minerals in the premix increase vitamin degradation rates.

Table 20 defines the trace mineral premix used for these diet examples. This premix is to be added and mixed thoroughly in the diet at specified levels for various pig classifications. Selenium is included in this example premix; but in some premixes, selenium is not included and must be added separately. The maximum level of supplemental selenium allowed by the U.S. Food and Drug Administration in finished swine feed is .3ppm.

Feed Additives

Feed additives are a broad classification of ingredients that do not contribute nutritional value. They include feed grade antibiotics, mold inhibitors, antioxidants, feed flavors, pelleting aids, feed flowing
agents, and enzymes to enhance nutrient availability. Dietary inclusion of feed additives is dependent on individual production situations. Growth promoting antibiotics are most commonly used, but the response is greatest and use most prevalent in weanling and nursery pigs. Whenever an antibacterial feed additive is used, it is essential to follow FDA approved mixing and feeding procedures and to meet all pre-slaughter withdrawal periods to avoid the potential for drug residues in pork.

One enzyme feed additive receiving attention in the swine industry is phytase. When properly supplemented in the diet, phytase can make chemically bound phosphorus in corn, soybean meal, and other grains more available for absorption by the pig. When supplementing phytase, the amount of inorganic phosphate supplement can be reduced in the diet. This practice can reduce the amount of phosphorus excreted in manure by 20-40%. This can be important on hog farms where the amount of manure that may be applied to agricultural land is limited due to phosphorus accumulation in the soil.

Feed Processing

For good results with any diet formulation, it is important that proper feed processing procedures are followed including proper grinding, mixing, pelleting (if applicable), and delivery of feed to the
pigs being fed.

Table 1

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Table 3

Table 4

Table 5

Table 6

Table 7

Table 8

Table 9

Table 10

Table 11

Table 12

Table 13

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Table 19

Table 20