Pigs consume their own feces, a behavior known scientifically as coprophagy. While this practice seems unhygienic to humans, it is common across the animal kingdom and serves a practical biological purpose for swine. It is a flexible mechanism for nutrient recovery, heavily influenced by the animal’s diet and immediate surroundings, rather than a sign of illness.
Is This Behavior Normal for Pigs
The consumption of feces is a natural behavior observed in many non-ruminant species, including pigs. Coprophagy in swine is classified as facultative, meaning it is not strictly required for survival, unlike the obligate coprophagy seen in species like rabbits. Young piglets exhibit a higher and more purposeful rate of this behavior early in life.
Nursing piglets are estimated to consume around 20 grams of their mother’s feces daily. This practice is critical for their development, as the ingestion of maternal feces helps inoculate the piglet’s gut with diverse microbial communities needed for proper digestion. Studies show that piglets with access to maternal feces exhibit better growth performance and higher weight gain compared to those deprived of the behavior.
Nutritional Reasons for Coprophagy
The primary driver behind coprophagy is the efficient recovery of nutrients not fully digested or absorbed during the first pass through the gastrointestinal tract. As monogastric animals, pigs have a digestive system that is less efficient at breaking down certain components, allowing undigested feed to pass into the feces. The feces contain significant amounts of protein, fatty acids, and minerals such as zinc, copper, and iron, which can be re-extracted upon consumption.
Fecal matter also provides access to essential B vitamins, which are manufactured by gut bacteria in the lower intestinal tract after the main absorption sites. Vitamin B12, or cobalamin, is synthesized exclusively by these microorganisms. Since B vitamin absorption occurs primarily in the small intestine, the bacteria-produced vitamins in the large intestine would be lost without coprophagy. Consuming the feces gives the pig a second opportunity to absorb these microbially-produced compounds, ensuring a more complete nutritional profile.
Environmental Factors That Influence Consumption
While nutrition is the internal driver, external factors and husbandry practices significantly increase the incidence of coprophagy in pigs. Diets that are restrictive or of poor quality, lacking sufficient fiber or certain minerals, encourage the pig to seek out nutrients in its own waste. A lack of environmental enrichment or stimulation can also exacerbate the behavior, as boredom and stress often lead to repetitive behaviors.
The physical conditions of the housing are directly correlated with the frequency of coprophagy. Overcrowding, poor ventilation, and continual exposure to contaminated areas elevate stress levels and increase the likelihood of the behavior. Maintaining clean housing with timely removal of feces is an effective management practice to reduce coprophagy in a herd. Environmental management plays a large role in mitigating this behavior, especially when combined with a balanced feed ration.