Feeding Growing Pigs

Feeding represents the single largest cost in raising pigs, typically accounting for sixty to seventy percent of total production expenses. How efficiently your pigs convert feed into meat determines whether you make money or lose it, and that efficiency depends heavily on what you feed, when you feed it, and how you manage the feeding program. Understanding the nutritional needs of growing pigs at different stages lets you optimize both growth rate and feed costs rather than throwing feed at pigs and hoping for the best.

Growing pigs progress through distinct nutritional phases from weaning through market weight, and each phase has different requirements. A recently weaned piglet weighing twenty pounds has a digestive system still developing and needs nutrient-dense, highly digestible feeds to maintain rapid growth without digestive upset. The same animal at one hundred fifty pounds has a mature digestive system capable of utilizing a wider range of feedstuffs and needs a different balance of protein and energy to maximize lean growth without excessive fat deposition. Feeding the right diet at the right time produces faster growth with less feed than using a one-size-fits-all approach.

Small-scale producers have options that large commercial operations do not, and some of these options can significantly reduce feed costs while producing excellent pork. Pasture, garden waste, dairy byproducts, bakery waste, and other alternative feeds can supplement or partially replace commercial feeds if you understand how to use them properly. At the same time, small producers often pay more per pound for commercial feeds than large operations, making feed efficiency even more important for profitability.

This guide covers the feeding requirements for pigs from weaning to market, including how to select appropriate commercial feeds, how to incorporate alternative feedstuffs, and how to manage feeding programs for good growth and efficient feed conversion. Whether you are raising two pigs in the backyard or fifty on a small farm, understanding pig nutrition helps you make better decisions about what to feed and how much to spend.

Protein is the building block for muscle growth, and growing pigs need adequate protein of good quality to achieve their genetic potential. Young pigs in the starter phase need the highest protein levels, around 20 to 22 percent crude protein, with that percentage declining as pigs mature. Grower feeds typically contain 16 to 18 percent protein, and finisher feeds drop to 14 to 16 percent. These declining protein levels match the pigs' changing physiology, where young pigs deposit proportionally more protein as muscle while older pigs shift toward more fat deposition.

Amino acid balance matters more than crude protein percentage. Lysine is typically the first limiting amino acid in pig diets, meaning it runs out before other amino acids and limits how much protein the pig can build. A feed with 16 percent crude protein from a poor lysine source may perform worse than a 14 percent protein feed with excellent amino acid balance. Soybean meal provides excellent amino acid balance for pigs, which is why it forms the protein base of most commercial pig feeds. Other protein sources like canola meal, sunflower meal, or field peas may require amino acid supplementation to achieve optimal performance.

Energy drives growth rate. Pigs that do not get enough calories grow slowly regardless of protein intake because they lack the energy to build tissue. Most pig diets derive energy primarily from cereal grains, with corn being the most common in North America and barley or wheat more common in other regions. Fat or oil can be added to increase energy density, which is particularly useful for young pigs that cannot physically eat enough volume of a lower-energy diet to meet their needs. However, too much fat in the diet reduces carcass quality by increasing back fat thickness.

Minerals and vitamins must be provided in appropriate amounts and balances. Calcium and phosphorus are needed in relatively large quantities for bone development, and the ratio between them matters as much as the absolute amounts. The optimal ratio is approximately 1.2 parts calcium to 1 part phosphorus for growing pigs. Excessive calcium interferes with absorption of other minerals, while inadequate phosphorus causes poor bone development and leg problems. Trace minerals including iron, copper, zinc, manganese, and selenium are needed in small amounts but cause deficiency symptoms if lacking. Commercial feeds are typically formulated with complete mineral and vitamin premixes, but home-mixed rations require careful attention to mineral and vitamin supplementation.

Water is the cheapest and most overlooked nutrient. Pigs drink roughly two to three pounds of water for every pound of feed consumed, more in hot weather. Inadequate water intake directly limits feed intake, which limits growth rate. Pigs with restricted water access grow more slowly and convert feed less efficiently than pigs with free access to clean water. Check waterers daily to ensure they are functioning properly and providing adequate flow. Dirty waterers reduce intake because pigs, like most animals, prefer clean drinking water.

Newly weaned pigs need special attention because the transition from sow's milk to solid feed stresses their immature digestive systems. Start with highly digestible, nutrient-dense starter feeds designed for this phase, and offer feed in small amounts frequently rather than filling feeders that may go stale before pigs eat it. Young pigs may be hesitant to eat at first, so observe to ensure every pig is finding the feeder and eating. Some producers add water to starter feed to make a gruel that encourages intake in the first days after weaning.

As pigs grow past the starter phase, transition them gradually to grower feeds over several days rather than switching abruptly. A sudden diet change causes digestive upset that shows up as reduced intake and sometimes scours. Mix increasing proportions of the new feed with decreasing proportions of the old feed over four to seven days. This transition principle applies whenever you change feeds, whether moving between commercial phases or incorporating new feedstuffs.

Monitor feed intake and growth to assess whether your feeding program is working. Pigs should show steady weight gain that you can see and feel week by week. If growth seems slow, evaluate whether pigs have adequate feeder access, whether water is freely available, and whether the feed quality and quantity are appropriate. Pigs that suddenly reduce feed intake may be sick, stressed, or dealing with environmental problems like heat or poor air quality. A drop in feed consumption is often the first sign that something is wrong.

Feeder management affects both growth and feed waste. Adjust feeders so pigs can access feed easily but not spill large amounts on the floor. Self-feeders that allow free-choice access work well for most growing situations, though some producers prefer controlled feeding for finisher pigs to manage fat deposition. If using self-feeders, check daily that feed is flowing properly and not bridging in the hopper. Clean out stale or contaminated feed that pigs refuse to eat. Feeders that allow pigs to root in the feed and scatter it on the ground waste money that goes directly into manure rather than into meat.

Nutrition and health interact in ways that affect both growth rate and feed efficiency. Pigs fighting disease divert nutrients from growth to immune function, growing more slowly and using more feed per pound of gain. Nutritional deficiencies weaken immune function, making pigs more susceptible to diseases that healthy, well-nourished pigs might resist. Feeding a balanced diet appropriate for each growth phase supports both maximum growth and disease resistance.

Scours and other digestive problems often trace to nutritional causes. Young pigs are particularly susceptible to digestive upset when weaned, when feed changes occur, or when feed quality is poor. Using highly digestible protein sources in starter feeds reduces the undigested material reaching the hindgut that feeds harmful bacteria. Avoiding abrupt feed changes allows the digestive system to adapt gradually. Ensuring feeds are fresh and not moldy prevents the toxins and palatability problems associated with spoiled feed.

Mycotoxins in contaminated grain cause a range of problems in growing pigs, from reduced feed intake to immune suppression to poor growth. Pigs are particularly sensitive to certain mycotoxins including vomitoxin, which causes feed refusal, and zearalenone, which disrupts hormonal function. Corn is especially prone to mycotoxin contamination in certain growing conditions. Store grain properly to prevent mold growth, use grain before it deteriorates, and be alert for signs of mycotoxin problems like reduced intake or poor performance. If you suspect mycotoxin contamination, have feeds tested and consider using mycotoxin binders.

Heat stress reduces feed intake and growth rate because pigs reduce eating to lower metabolic heat production. This is particularly problematic during the finisher phase when pigs are large enough to generate significant metabolic heat but have not yet reached market weight. Provide shade, ensure ventilation, make sure cool water is always available, and consider feeding during the cooler parts of the day during hot weather. Pigs that stop growing during heat stress require longer to reach market weight, which increases total feed costs and delays cash flow.

Heritage breeds typically grow more slowly than commercial breeds but often produce pork with superior flavor and marbling. Expecting a Berkshire or Large Black to gain weight at the same rate as a commercial hybrid leads to frustration and wasted feed trying to push genetics that were never selected for maximum growth rate. Feed heritage breeds for steady growth appropriate to their genetics rather than forcing maximum intake. The longer time to market allows more fat deposition, which contributes to flavor and is valued in heritage pork.

Commercial breeds and crosses have been selected for rapid lean growth and efficient feed conversion. These genetics can reach market weight of 250 to 280 pounds in five to six months under good management, with feed conversion ratios approaching 3:1 in the finisher phase. Realizing this genetic potential requires high-quality feeds matched to the pigs' needs at each growth phase. Underfeeding commercial genetics leaves growth potential on the table, while the wrong nutrient balance may produce acceptable growth but with more fat than desired.

Pasture-raised pigs have different nutritional dynamics than pigs raised in confinement because they obtain some nutrition from grazing and rooting. How much nutrition pasture provides depends on the pasture quality, season, and stocking density. In good conditions, pasture may replace fifteen to twenty-five percent of complete feed requirements, reducing feed costs significantly. In poor conditions or when overstocked, pasture contributes negligible nutrition and pigs need essentially full feeding. Observe pasture-raised pigs carefully and adjust supplemental feeding based on body condition and growth rate rather than assuming fixed percentages.

Feeding the same diet from weaning to market ignores the changing nutritional needs of growing pigs and wastes money. Young pigs fed finisher feeds grow slowly because protein is inadequate for rapid muscle development. Finisher pigs fed starter diets waste money on protein they cannot use efficiently, which ends up in manure rather than in meat. Use phase feeding that matches diet composition to the pigs' current needs, or at minimum use at least two different diets, one for growing and one for finishing.

Overfeeding protein to finisher pigs is expensive and counterproductive. Once pigs pass their maximum protein deposition rate, additional dietary protein cannot be converted to muscle. The excess is broken down and the nitrogen excreted, wasting expensive feed protein while increasing ammonia in the manure and building. Match protein levels to actual requirements rather than assuming more is always better.

Relying on low-quality alternative feeds without balancing the total ration leads to poor growth and inefficient feed conversion. Bakery waste, garden scraps, dairy byproducts, and similar alternative feeds can reduce costs when used properly, but they cannot replace a balanced diet. Use alternative feeds as supplements to commercial feeds rather than replacements, and adjust the amount of commercial feed based on the nutritional contribution of the alternatives.

Ignoring water availability limits growth in ways that feed quality cannot overcome. Pigs that cannot drink enough grow slowly even when excellent feed is available. Check waterers daily, clean them regularly, and ensure flow rates are adequate for the number of pigs drinking. In freezing weather, this may mean checking multiple times daily to prevent ice blockages.

Neglecting feeder adjustment wastes feed on the ground instead of converting it to pork. Self-feeders need regular adjustment as pigs grow to maintain proper flow without excessive spillage. A feeder that worked perfectly for fifty-pound pigs needs readjustment as those same pigs grow to one hundred fifty pounds. Check feeders daily for proper operation and adjust as needed. Feed on the ground is feed converted directly to manure rather than to saleable pork, and at current feed prices, that waste adds up quickly.