Recent University of Wisconsin research has affirmed that supplementing dietary vitamin D is essential for enhancing pigs’ productivity and bone development. Vitamin D is needed for the efficient absorption and metabolism of calcium and phosphorus and is required for normal bone growth.

A vitamin D deficiency in young pigs can result in rickets, stiffness, lameness and general unthriftiness. In mature animals, broken bones may result if vitamin D is deficient.  

Kansas State University researchers are evaluating supplemental vitamin D requirements in commercially raised pigs. “Supplementing with calcium and phosphorus is not as effective without adequate amounts of vitamin D,” says Steve Dritz, DVM, swine specialist, Kansas State University. “If vitamin D is not supplemented in swine diets at adequate levels it will be a problem.”

Kansas State’s current vitamin D feeding recommendations are between six and eight times the National Research Council recommended levels. (Go to for more.) Feeding higher levels is not a significant cost, Dritz points out, since the cost of vitamin D consumed in a pig’s lifetime is pennies. However, feeding greater than 10 to 20 times NRC-recommended levels for extended periods can lead to toxicity. Also, high dietary levels of vitamin D can reduce feed intake, so there’s a need for caution at high dietary vitamin D levels.

Vitamin D is typically supplied in vitamin/trace mineral combination premixes, but it’s still worth watching. The vitamins may not retain potency as long when mixed with trace minerals, so product must be rotated frequently and kept fresh. Thus, from a stability standpoint you may want to keep the vitamin premix and trace mineral premix separate.

Dritz recommends these steps to eliminate premix errors to ensure that vitamin D levels, as well as other nutrients present in premixes, are supplied in adequate amounts in swine diets:

  • Develop clear premix specifications and use reputable premix suppliers.
  • Verify nutrient levels supplied by reviewing premix production batch sheets.
  • Keep vitamin premix separate from trace mineral premixes and ensure proper product rotation.
  • Consider testing premix to verify nutrient levels present.
  • Don’t add nutrients by hand at mixing.
  • Evaluate feed mixer function to ensure mixing efficiency and consistency.