Essential Minerals for Pig Nutrition
Why minerals are important to a pig's diet.
Reading Time: 6 minutes
Providing healthy minerals is essential in pig nutrition. Learn why minerals are important, types of swine minerals and vitamins, and how to ensure your soil is suitable for pasture-raised pigs.
by Jodi Cronauer
When a pig becomes deficient in a mineral, its body starts to crave that mineral, and naturally wants more. Minerals are found in dirt, so it only makes sense that the pigs will start to dig in the ground to get more minerals.
How you feed your pigs will determine how you need to mix your minerals and at what ratio. Many pasture-raised pigs are hand-fed daily or twice daily as compared to commercially raised pigs, which are fed free-choice each day. For this reason, minerals mixed into feed for mass-raised pigs won’t be the same for hand-fed, pasture-based pigs. Unfortunately, not all swine mineral mixes sold in the United States contain the same percentages of different minerals. For that reason, it’s particularly important to get a mineral mix that contains the necessary minerals.
Across the United States, the mineral content of the soil will vary, which means that the grains and grasses grown in the soil will also vary in the quantity of minerals they contain. A deficiency will carry over into everything grown in that deficient soil.
Selenium
Signs and symptoms of selenium deficiency in adult pigs are mulberry heart disease, impaired farrowing, reproductive problems, inflammation of the uterus, decreased immunity, increased mastitis, decreased milk supply, decreased reproductive performance in boars, miscarriages, retained placenta, infertility, and chronic infections.
In young pigs, the signs and symptoms present as muscle dystrophy, lameness, weakness and stiffness, liver necrosis (presenting as behavioral abnormalities such as a stupor, ataxia, loss of righting, and seizures), diarrhea, inability to thrive, and if swallowing muscles are affected, piglets may inhale food instead of eating it.
In both adult and young pigs, sudden death is a possibility.
Selenium toxicity, although rare, is a concern that should be taken seriously, as well. Signs and symptoms of toxicity are reduced feed intake, slower growth, loss of hair, stiffness, separation of the hooves at the coronary band, joints issues, atrophy of the heart, anemia, and impaired embryo development.
Salt
Pigs can become deficient if they don’t get the necessary salt in their diet. Having a decreased level of salt can lead to poor growth (primarily due to diminished feed intake) and poor hair and skin condition.
Pigs can also develop salt toxicity because they’re unable to sweat, so they don’t have a way to efficiently remove excess salt from their bodies. For this reason, it’s advised not to provide salt blocks, mineral blocks, or free-choice salt to your pigs, but instead to make sure they’re getting the correct amount their bodies require by mixing it into their feed.
The signs and symptoms of salt toxicity can be apparent blindness, loss of balance and falling over, vomiting, or seizures. Providing ample water for your pigs to drink at all times is extremely important.
Calcium and Phosphorus
These two minerals are the most abundant minerals in a pig’s body. They are essential for skeletal development and maintenance, so it won’t surprise you to learn that a deficiency will greatly affect the pig’s bone and muscle structure.
A deficiency in these two minerals can lead to decreased bone mineralization, reduced bone strength, decreased growth, rickets, osteoporosis, lameness, fractures, deformation and bending of long bones, and fractures in the lumbar region of the spine (butt and back region). Nursing sows may develop posterior paralysis because the mammary system pulls calcium from the sow’s bones to supplement their milk for their young.
Calcium toxicity is exceedingly rare and is most often associated with decreased absorption of phosphorus or vitamin D. Toxicity can result in calcification of internal organs.
Vitamin D deficiency is less common as this vitamin is readily available from the sun.
The calcium and phosphorus ratio influences the absorption and retention of both minerals. Swine diets must provide not only the necessary individual requirements of calcium and phosphorus, but also an adequate ratio of one mineral to the other, which can vary depending on the pig’s weight and dietary goal.
Zinc
Zinc aids in the metabolism of carbohydrates, proteins, and lipids.
A zinc deficiency occurs for one of two reasons: a true deficiency of zinc, or an excess of calcium and phosphorus in the diet, which impairs the absorption of zinc. (This is why a balanced mineral intake is so important to your pigs’ diet.)
Signs and symptoms of zinc deficiency are parakeratosis (indicated by lesions on the top layer of the skin usually affecting the lower legs and abdomen first). Parakeratosis usually affects piglets from 6 to 16 weeks old. Other signs may include low growth rate, anorexia, mild lethargy, and decreased reproductive performance.
Zinc toxicity is rare but may lead to pancreatitis.
Copper and Iron
For those of you wondering why I would put these minerals together, let me explain.
- Copper aids in iron absorption and the synthesis of hemoglobin.
- Iron aids in the synthesis of hemoglobin.
This means that both copper and iron are essential to producing red blood cells, which carry oxygen throughout the body.
A deficiency in copper leads to anemia and low growth rate.
Iron deficiency causes anemia, which presents as pale mucous membranes, listlessness, enlarged heart, skin edema around the head and shoulders, and spasmodic breathing.
A deficiency in iron is more common in young piglets, but there are a few options to ensure they get the proper amount of iron. One option is to provide soil for the piglets to nose through. If your soil is high in iron, this is the easiest and simplest approach. As the piglets nose through the soil, they get the iron their body requires. Another option, and one that may be necessary if your soil isn’t high in iron, is to give newborn piglets iron shots. Iron toxicity can be caused by giving too much iron when administering an iron shot to a young piglet. It’ll present with the following signs and symptoms: vomiting, diarrhea, abdominal pain, low blood pressure, seizures, coma, organ damage, and possibly death. Consult with a local vet to see if iron shots are recommended in your area.
Manganese
Manganese is important in bone development and can be found in grains at a low concentration. Depending on the amount present in the grains used to make your pig’s feed, you many need to add manganese to your pigs’ diet to ensure proper growth and development.
Another key role of manganese is to boost the pig’s stress defense. An example is the stress on a piglet at weaning. Manganese has been found to decrease “pathogenic or bad” bacteria and increase “beneficial or good” bacteria in a pig’s gut. This boosts the immune system and helps in the piglet’s overall growth. Signs and symptoms of manganese deficiency are improper bone development, lameness, and slow growth rate.
All the minerals mentioned here are essential to the overall health of your pigs. Knowing what minerals are present in your soil and feed will ensure the best results in providing the necessary minerals to your pigs.
Remember, most feed mills across the United States have a nutritionist on hand to assist you. Depending on how your pigs are raised, you may have to help educate the nutritionist as to why your pigs are different than mass-raised pigs. Pigs that are hand-fed small amounts of feed get nutrients from grasses and legumes, which will affect their nutritional requirements. Once they understand why and how you’re raising your pigs, most nutritionists will be happy to assist you in providing the best for them.
Jodi Cronauer lives in Wisconsin with her husband and her three sons. They raise Idaho Pasture pigs, Kunekune pigs, and American bison as well as Gypsy Vanner horses. The meat from their pigs and bison is rich in essential nutrients because they eat grass as their primary diet. Jodi is the author of Raising Pigs on Green Pastures (Dorrance Publishing, 2021).
Originally published in the May/June 2025 issue of Countryside and Small Stock Journal and regularly vetted for accuracy.
