The best feed for pigs is a corn and soybean meal-based diet, adjusted for the pig’s age and life stage. This combination has been the industry standard for decades because corn provides affordable energy while soybean meal supplies the protein and amino acids pigs need to grow efficiently. But getting the ratio right, and knowing what to add (and what to never feed), makes the difference between mediocre and excellent results.
Why Corn and Soybean Meal Are the Foundation
Corn can make up as much as 80% of a pig’s total diet by weight. It’s the primary energy source in most swine rations. Soybean meal, typically included at up to 35% of the diet, fills the protein gap. Together they form the backbone of commercial pig feed worldwide.
Corn alone falls short in two critical amino acids: lysine and tryptophan. Soybean meal compensates for this, but most diets still add a small amount of supplemental lysine (around 0.1%) to hit optimal levels. The remaining 3% or so of the diet goes to a mineral and vitamin premix. If corn or soy prices spike, other grains like barley, wheat, or grain sorghum can substitute for corn on an equal-weight basis, though they’re also low in lysine and threonine, so protein supplementation still matters.
Feeding by Life Stage
Starter Pigs (Under 25 Pounds)
Young pigs have immature digestive systems and need highly digestible, energy-dense feed. Diets for piglets in the 11 to 25 pound range typically include specialty ingredients like dried whey, lactose, dried blood plasma, and dried blood cells. These provide easily absorbed protein and help ease the transition from sow’s milk to solid feed. Standard grain-soy diets are too harsh for very young piglets and can cause digestive upset.
Growing and Finishing Pigs (25 to 280 Pounds)
Once pigs move past the starter phase, a straightforward corn-soybean meal diet becomes the core ration. Early in the growing phase, pigs convert feed very efficiently, at less than 2 pounds of feed per pound of gain. As they approach market weight, that ratio climbs significantly. A 245-pound pig converts feed at about 3.46:1, while a 275-pound pig needs 4.09 pounds of feed per pound of gain. That’s an 18% drop in efficiency over just 30 pounds of growth, which is why many producers target market weights carefully to keep feed costs in check.
Growing hogs on pasture (40 to 125 pounds) need pasture supplements including soybean meal, ground limestone, dicalcium phosphate, salt, and vitamin and trace mineral premixes. Together, pasture and supplemental feed should provide at least 0.76 pounds of protein, 18 grams of lysine, 13 grams of calcium, and 11 grams of phosphorus per day.
Gestating Sows
Pregnant sows in late gestation (day 90 to 115) need roughly 8,200 calories per day, with a diet containing about 14.7% crude protein and 0.80% lysine. Calcium requirements are relatively high at 0.83%, supporting skeletal development of the piglets. Water intake ranges from 3 to 6 gallons per day. Overfeeding during gestation causes excess weight gain that can lead to farrowing problems, so controlled feeding is standard practice.
Lactating Sows
Milk production is the most nutritionally demanding phase of a sow’s life. Energy needs more than double compared to late gestation, jumping to around 20,700 calories per day. Crude protein rises to about 16.1%, and lysine requirements increase to 0.93%. Copper requirements double from 10 to 20 parts per million. Lactating sows drink 5 to 10 gallons of water daily. Restricting feed or water during lactation directly reduces milk output and piglet growth rates.
Essential Minerals and Vitamins
A mineral and vitamin premix is not optional. Corn-soy diets alone cannot meet a pig’s full micronutrient needs. The premix typically accounts for about 3% of the total diet and supplies calcium, phosphorus, salt, and trace minerals like copper, along with vitamins A, D, and E. Calcium and phosphorus are especially important for bone development and reproductive performance, with requirements varying by life stage. Late-gestation sows, for example, need 0.83% calcium in their diet, while lactating sows need about 0.68 to 0.71%.
One of the most impactful feed additives in modern pig production is phytase, an enzyme that breaks down phytate, the form in which most phosphorus is locked up in plant-based ingredients. Without phytase, pigs can only break down about 16% of the phytate in a corn-soy diet by the time it reaches the end of the small intestine. Adding phytase at the standard rate triples that breakdown to around 45 to 60%. Higher doses push degradation to 56 to 88%. This means pigs absorb significantly more phosphorus, calcium, and amino acids from the same feed, reducing the need for expensive inorganic mineral supplements. It also cuts phosphorus in manure by about 36%, which matters for environmental compliance.
Pellets vs. Meal: Which Form Is Better
Pelleted feed improves feed efficiency compared to meal (ground, loose feed). Pigs fed pellets throughout the finishing period had the best feed-to-gain ratio, while pigs fed meal had the worst. However, pellets come with a tradeoff: pigs on an all-pellet diet had higher rates of stomach ulceration and keratinization, and more pigs had to be removed from pens due to health problems.
A practical middle ground is rotating between pellets and meal. Pigs that alternated between the two feed forms had intermediate feed efficiency while experiencing fewer stomach issues than those fed only pellets. If you’re feeding pellets, monitoring for signs of digestive distress is important.
Water: The Overlooked Nutrient
Pigs need two to three times as much water as feed by weight. Nursery and grow-finish pigs typically consume water at a 2:1 to 3:1 ratio relative to feed intake, with the ratio declining slightly as pigs grow. Newborn piglets drink only about 1.5 ounces per day, gradually increasing to around 1.5 cups daily by weaning at 28 days. Inadequate water supply directly reduces feed intake, which slows growth. Clean, fresh water available at all times is one of the simplest ways to improve feed performance.
What You Should Never Feed Pigs
In most countries, it is illegal to feed pigs any food that contains or has come into contact with meat or meat products. This includes household table scraps, pizza, pies, sausage rolls, deli meats, restaurant waste, and discarded cooking oils. Even food stored or transported in containers that previously held meat (like takeaway boxes or meat trays) is prohibited.
These laws exist because meat-contaminated feed can carry viruses that cause catastrophic diseases like foot and mouth disease and African swine fever. These diseases spread rapidly through pig populations and can devastate entire herds and regional industries. The rule is simple: if you’re unsure whether something has contacted meat, don’t feed it to your pigs.
Pasture-Raised Pigs Still Need Grain
Forages alone cannot meet a pig’s nutritional needs. Pasture plants are low in dry matter and energy density, making them especially impractical as a sole feed source for young growing pigs and lactating sows. When diets contain more than 25% forages, the protein content of the supplemental feed needs to be bumped up above what a standard grain-soy diet provides.
Gestating sows on pasture need supplemental soybean meal, limestone, phosphate sources, salt, and vitamin and trace mineral premixes. Pasture plus these supplements together should deliver at least 0.75 pounds of protein, 17 grams of lysine, 18 grams of calcium, and 14 grams of phosphorus per day. Pasture is a valuable addition to a sow’s diet for exercise, enrichment, and some nutrient contribution, but it’s a complement to grain-based feed, not a replacement.