Freshly weaned piglets need highly digestible, energy-dense feed built around lactose, quality protein sources, and grain. The transition from sow’s milk to solid feed is one of the most stressful periods in a pig’s life, and getting the diet right during the first few weeks determines how quickly piglets recover and start gaining weight. A well-fed nursery pig can gain 500 to 600 grams per day (roughly 1.1 to 1.3 pounds) in the weeks after weaning, but poor nutrition during this window leads to gut problems, slow growth, and increased disease risk.
Why Weaning Is So Hard on Piglets
When piglets lose access to sow’s milk, their digestive system has to rapidly adapt. The enzyme that breaks down lactose (the main sugar in milk) stays high during nursing but drops sharply after weaning, typically between 3 and 5 weeks of age. At the same time, the enzymes needed to digest starch and plant proteins are still maturing. This mismatch means piglets can’t efficiently handle a standard grower diet right away. Feeding complex plant-based ingredients too early causes diarrhea, poor absorption, and a growth slump that can last a week or more.
Piglets are also especially sensitive to anti-nutritional factors in raw soybean meal, including compounds called glycinin and beta-conglycinin that irritate the gut lining. This is why early nursery diets rely on processed, highly digestible protein sources rather than standard soybean meal.
Lactose: The Most Important Ingredient Early On
Lactose should be the dominant energy source in the first week after weaning. A meta-analysis published in the Journal of Animal Science and Biotechnology found that optimal piglet growth requires about 20% dietary lactose from day 0 to 7 post-weaning, 15% from day 7 to 14, and none after day 14. In that first week, piglets still have enough lactase enzyme to handle high quantities of milk sugar, so there’s no upper limit concern for growth performance. By the second week, though, daily gain actually drops when lactose exceeds 15% of the diet.
The most common lactose source in piglet feeds is dried whey powder, which also contributes some protein. Straight lactose powder works too. After two weeks, you can phase lactose out entirely and shift toward grain-based energy.
Protein Sources That Young Guts Can Handle
Early nursery diets typically contain up to 22% crude protein, though this can be reduced to around 18% when supplemented with individual amino acids like lysine, methionine, and threonine. The key amino acid to get right is lysine: aim for 1.35 to 1.40% standardized ileal digestible lysine for piglets between about 12 and 25 pounds.
The best protein sources for freshly weaned piglets are highly digestible animal-derived ingredients. Fish meal is a longstanding choice, providing concentrated protein along with calcium and phosphorus. Spray-dried porcine plasma is another premium option, with protein digestibility around 84%. Both of these outperform standard soybean meal in young piglets. Fermented soybean meal and soybean protein concentrate are plant-based alternatives that have had their anti-nutritional factors reduced through processing, making them much easier on piglet guts than raw soybean meal.
Egg powder and potato protein are also used in commercial starter diets at lower inclusion rates (typically 1.5 to 3%) to round out the amino acid profile. These specialty ingredients are expensive, which is why nursery diets cost more per ton than grower feeds, but the payoff in growth and health is significant.
Grain and Energy Sources
Wheat and barley form the grain base of most nursery diets. Extruded (heat-processed) wheat is preferred for the earliest phase because the cooking process breaks down starch granules, making them easier to digest before the piglet’s own starch-digesting enzymes fully mature. A typical starter formula might include 25 to 30% standard wheat plus another 18 to 20% extruded wheat, with 8 to 10% barley.
Soybean oil at around 5% of the diet adds caloric density without increasing bulk, which matters because piglets have small stomachs and limited appetite in the first days after weaning. Small amounts of medium-chain fatty acids (from coconut or palm kernel oil) are sometimes added because they’re absorbed more easily than long-chain fats.
Feeding Schedule and Physical Feed Form
Let piglets eat freely (ad libitum) from the start. Research from Institut Agro Rennes-Angers showed that restricting feed during the first days post-weaning reduced growth, raised stress hormones (cortisol), and increased markers of inflammation. Restricted piglets didn’t gain any gut health advantage. Even in less-than-ideal sanitary conditions, restriction made things worse rather than better.
Piglets will eat very little in the first 24 to 48 hours regardless, so the goal is simply to have fresh feed available at all times. Offer small amounts frequently and remove stale feed to keep the trough appealing. Feeding four to six times daily in the first few days encourages piglets to approach the feeder.
Pellet size matters more than most producers realize. Research in Translational Animal Science found that piglets offered 12-mm pellets showed significantly more eating behavior and higher feed disappearance compared to standard 2-mm pellets or crumbles. Larger pellets seem to attract piglets and stimulate exploratory feeding. That said, most commercial nursery feeds come as 2 to 3 mm pellets or crumbles, and piglets do fine on these once they’ve learned to eat. If you’re having trouble getting piglets to start eating, offering some larger pellets alongside the standard feed can help.
Water Access Is Just as Important as Feed
Piglets drink roughly 2 to 3 times as much water by weight as they eat in feed. For nursery pigs, a water-to-feed ratio of 2:1 to 3:1 is normal. Nipple drinkers should deliver 1 to 2 cups per minute for nursery-age pigs. A quick check: if it takes more than 2 minutes to fill a 16-ounce bottle from the drinker, the flow rate is too low. Piglets that can’t get enough water eat less, and dehydration compounds the gut stress that weaning already causes.
Supporting Gut Health Without Antibiotics
Organic acids are one of the most effective tools for keeping piglet guts healthy after weaning. They work by lowering the pH in the stomach, which improves protein digestion and creates an environment hostile to harmful bacteria. Benzoic acid at 0.5% of the diet is widely used and has strong evidence for improving nutrient digestibility and suppressing pathogens. Sodium butyrate at low levels (around 0.035%) complements benzoic acid by supporting immune function and serving as a direct energy source for gut lining cells.
A study in the journal Microorganisms found that piglets fed a combination of benzoic acid and sodium butyrate at these levels developed more diverse gut bacteria populations, with increases in beneficial microbes and reductions in potentially harmful ones. Formic and acetic acid blends (at around 0.2% of the diet) are another common acidifier used in commercial starter feeds.
The European Union banned pharmacological levels of zinc oxide in piglet feeds, previously used at high doses to prevent post-weaning diarrhea. The current authorized level in the EU is 150 mg/kg of zinc from all sources. Producers who relied on high-dose zinc oxide have shifted toward organic acids, probiotics, and better dietary formulation to fill the gap.
Phase Feeding: Changing the Diet as Piglets Grow
The nursery period isn’t one diet; it’s a series of transitions. A common approach uses three phases:
- Phase 1 (days 0 to 7 post-weaning): The most digestible, most expensive diet. High lactose (around 20%), premium protein sources like spray-dried plasma and fish meal, extruded grains, and minimal soybean meal. This phase is about getting piglets eating and protecting their gut.
- Phase 2 (days 7 to 14): Lactose drops to about 15%. You can begin introducing more soybean protein concentrate and fermented soybean meal while reducing the most expensive ingredients. Crude protein stays around 20 to 22%.
- Phase 3 (days 14 to 35): Lactose is no longer needed. Standard soybean meal can make up a larger share of the protein. Grain inclusion increases. This diet starts to resemble a grower feed, though it’s still more nutrient-dense than what finishing pigs eat.
Each phase transition should be gradual when possible, blending the old and new feed over 2 to 3 days to avoid sudden dietary shocks. By the end of the nursery period, around 7 weeks post-weaning, well-managed piglets typically reach 40 to 45 kg and are gaining over 500 grams per day on a standard nursery program.