Pigs are highly adaptable animals whose diet is fundamentally shaped by their environment, ranging from natural foraging to scientifically formulated commercial feeds. Their consumption habits are linked to their classification as omnivores, meaning they naturally eat both plant and animal matter. Understanding what pigs eat balances their opportunistic biology with the precise nutritional requirements of modern livestock production.
Pigs are Omnivores and Foraging Eaters
Pigs possess a digestive system similar to humans, classifying them as non-ruminant omnivores. When permitted to forage, a pig’s diet is varied and opportunistic, adapting to seasonal availability and local resources. Their strong, disk-shaped snout is an adaptation for rooting, which they use to dig into the soil to unearth food items.
Their natural diet consists mostly of plant material, including roots, tubers, bulbs, green plants, fallen fruits, seeds, and nuts like acorns. Animal matter is a regular part of their foraging intake. This includes invertebrates such as earthworms, insects, and crustaceans, along with small vertebrates, carrion, and eggs. Feral pigs consume between 3% and 5% of their total body mass daily, adjusting their diet as new seasonal foods become available.
Structured Diets in Commercial Farming
In commercial settings, the diet of pigs is precisely controlled through structured rations designed to optimize growth, health, and feed efficiency. These rations are formulated to provide a balance of energy, protein, and essential amino acids, which represent the major costs in swine production. The goal is to maximize the pig’s genetic potential for rapid, lean growth.
The primary component of commercial pig feed is an energy source, typically composed of cereal grains such as corn, wheat, or barley. Corn is often the major energy feed, and these ingredients supply the necessary carbohydrates for weight gain. Protein is the second main component, supplying the amino acids required for muscle development and bodily maintenance.
Soybean meal is the most common protein source in swine diets because its amino acid profile complements corn. Nutritionists focus on meeting the requirements for lysine, which is often the first-limiting amino acid in corn-soybean meal diets. The formulated feed also includes supplements such as vitamins, minerals, and specialty ingredients like dried distillers grains or vegetable oils, to ensure a complete and balanced diet.
Adapting Feed Based on Life Stages
The composition of the commercial diet changes throughout a pig’s life to match its evolving nutritional needs, with diets tailored for specific physiological stages. This maximizes feed efficiency and growth rates during different phases. The initial stage is the Starter diet, or creep feed, which is highly digestible, nutrient-dense, and formulated for piglets transitioning from sow’s milk to solid feed.
Starter feeds are rich in highly digestible proteins, milk products like whey, and lactose, supporting the development of the piglet’s gut and immune system. As the pig grows past the nursery phase and reaches approximately 25 to 125 pounds, it moves to the Grower diet. This ration maintains high levels of protein and energy to support rapid muscle development.
The final phase is the Finisher diet, fed from around 125 pounds until the pig reaches market weight. Finisher rations contain a higher energy-to-protein ratio compared to grower diets, designed to optimize weight gain efficiently. Breeding animals, such as sows and boars, are given specialized maintenance diets, like gestation or lactation formulas, managed to control body condition and support reproductive health.
Important Dietary Restrictions and Safety
A legal prohibition in pig husbandry is the feeding of swill, defined as any food waste containing or having come into contact with meat or meat products. This ban is enforced globally because swill can transmit devastating animal diseases, such as Foot-and-Mouth Disease (FMD) and African Swine Fever (ASF). These diseases can survive in meat products even after chilling, freezing, or inadequate cooking.
The restriction applies universally to all pigs, including pet pigs and those kept for home consumption. It includes items like table scraps, bakery waste, and untreated used cooking oils that may have contacted meat or material of mammalian or avian origin. In addition to these legal restrictions, care must be taken to prevent pigs from consuming toxic substances or plants.