Pigs have a reputation for eating almost anything, but several common foods can sicken or kill them. Some are toxic at the cellular level, others carry disease risks serious enough to be regulated by federal law. Whether you’re raising a few backyard pigs or managing a larger herd, knowing what to keep out of the trough is essential.
Meat, Fish, and Kitchen Scraps
Feeding pigs food waste that contains or has been in contact with meat, poultry, or fish is regulated under the federal Swine Health Protection Act. Uncooked meat scraps can carry viruses that cause devastating swine diseases, and garbage feeding has triggered disease outbreaks in multiple countries. If you collect food waste from restaurants, school cafeterias, or food processing facilities, you need a license, and that waste must be cooked to 212°F (100°C) for a full 30 minutes before it goes to your pigs. This isn’t a suggestion; it’s a legal requirement enforced by USDA’s Animal and Plant Health Inspection Service.
The simplest approach for small-scale pig owners is to avoid feeding meat-containing kitchen scraps altogether. The risk of introducing a pathogen that spreads through your herd far outweighs any savings on feed costs.
Green Potatoes, Sprouts, and Nightshade Plants
Green potatoes and potato sprouts contain glycoalkaloids, a group of naturally occurring toxins that concentrate in the green-tinged skin and in any sprouts growing from the tuber. Historical records from Poland documented outbreaks of glycoalkaloid poisoning in pigs that killed 64% of the 180 animals affected. The toxic compounds are not destroyed by cooking at normal temperatures, so simply boiling green potatoes does not make them safe.
Other parts of nightshade-family plants carry similar risks. Tomato vines and leaves, the green portions of eggplant plants, and any unripe green tomatoes should stay out of pig feed. Ripe tomatoes and fully mature, non-green potatoes are generally fine, but trim away any green patches or sprouts before feeding.
Avocado
Every above-ground part of the avocado plant contains persin, a toxin that causes effects ranging from gastrointestinal irritation to rapid death depending on the species and amount consumed. The skin, pit, leaves, and bark all carry persin, and fatal poisonings have been documented in goats, sheep, horses, and birds. While pig-specific case reports are limited, the toxin is present in the flesh as well, and the safest practice is to keep avocados and avocado scraps away from pigs entirely.
Onions and Garlic
Onions and garlic belong to the Allium family, and they contain sulfur-based compounds that damage red blood cells. When pigs eat raw, cooked, or concentrated forms of these foods, the oxidant compounds are absorbed and begin destroying red blood cells within 24 hours, with the damage peaking around 72 hours. This leads to a type of anemia where the blood loses its ability to carry oxygen effectively. Pigs are more susceptible to this than sheep or goats, so even moderate amounts of onion or garlic in feed should be avoided.
Moldy or Spoiled Grain
Corn is the backbone of most pig diets, but grain that has been stored in warm, humid conditions can develop mold that produces invisible toxins called mycotoxins. These are among the most common and underrecognized dangers in pig feeding. The toxins that matter most are produced by Aspergillus and Fusarium molds, and they frequently contaminate corn, wheat, and other cereal grains.
One of these toxins causes liver damage and immune suppression under chronic exposure. Another specifically reduces feed intake in pigs by interfering with gut signaling, increasing feelings of satiety, triggering inflammation, and potentially causing vomiting. Pigs start showing reduced growth when this toxin reaches even low concentrations in their feed (1 to 3 milligrams per kilogram of feed). A third group damages both intestinal lining and immune function.
The tricky part is that moldy grain doesn’t always look or smell obviously spoiled. Grain that sat in a damp barn over summer or was harvested in wet conditions can harbor dangerous levels of these toxins while appearing mostly normal. If you’re buying feed corn, source it from reputable suppliers and store it in cool, dry conditions. Any grain with visible mold growth should be discarded, not fed.
Too Much Salt (Especially Without Water)
Salt is a normal part of pig diets at 0.4% to 0.6% of the ration, and pigs can tolerate up to 2% or more if they have unlimited access to fresh water. The danger comes when pigs eat salty food and then can’t drink enough. Even normal salt levels in feed can trigger toxicity after just 48 hours of water deprivation. Salt poisoning affects the brain and nervous system and can be fatal. This is most commonly an issue when waterers freeze in winter, break down, or get blocked, so checking water access daily is as important as monitoring what goes into the feeder.
Other Foods to Avoid
- Raw beans and raw soybeans: These contain compounds that interfere with protein digestion. Cooking neutralizes them, which is why processed soybean meal is a standard pig feed ingredient but raw soybeans are not.
- Fruit pits and seeds: Cherry pits, apple seeds, and peach pits contain compounds that release cyanide when crushed. A few apple seeds are unlikely to cause problems, but large quantities of stone fruit pits can be dangerous.
- Rhubarb leaves: High in oxalic acid, which can cause kidney damage. The stalks are less concentrated but still not ideal as feed.
- Processed human foods: Chocolate, candy, and heavily seasoned or sugared foods offer no nutritional value and can cause digestive upset or contribute to obesity. Pigs gain weight easily, and excess sugar or fat in the diet creates health problems over time.
The general rule is straightforward: if it’s moldy, toxic to other livestock, or contains meat, don’t feed it to pigs. Stick to quality grain, fresh fruits and vegetables (avoiding the items listed above), and commercial pig feed formulated for their life stage, and your animals will thrive.