Dietary vitamin C helps health-challenged pigs

By Michael Edmonds and Jon Bergstrom
Originally appeared in Feedstuffs on October 28, 2013. Reprinted with permission.

Increasing serum vitamin D levels with the use of a stabilized form of vitamin C is an important finding to help the pork industry make progress towards addressing many issues that may be associated with vitamin D status.

Swine producers are continually faced with the challenges of getting weaned pigs off to a good start.

In addition to the normal stresses associated with weaning, pigs may be exposed to conditions and pathogens that may further compromise their health, feed intake and growth.

After weaning, it is extremely important for pigs to begin eating quickly and have access to a diet that provides energy and essential nutrients for optimum health and growth performance.

Therefore, we elected to evaluate supplementing starter diets with a stable form of vitamin C (Rovimix Stay-C 35).

Vitamin C has multiple functions in the body, such as helping with enzyme systems that synthesize collagen, assisting with the absorption of dietary minerals, sparing vitamin E, as an antioxidant that helps maintain the immune system, wound healing and helping convert 25-hydroxyvitamin D3 (the storage form of vitamin D3) to 1,25-dihydroxyvitamin D3 (the active form of vitamin D3).

The need for dietary vitamin C in mammals is usually limited to humans, non-human primates, guinea pigs and fruit-eating bats. Most mammalian species — including swine, under normal conditions — can synthesize their own vitamin C. However, there are data suggesting that weanling pigs experiencing increased levels of stress can benefit from added vitamin C in their diets.

Factors that may result in a conditional dietary requirement for vitamin C to optimize health and performance are younger weaning ages, genetics, decreased feed intake, dietary changes, a new environment, poor biosecurity, new pathogens, commingling, vaccinations and poor housing conditions.

In addition, with vitamin D issues plaguing the entire feed industry in the last four years, we believed it was important to not only look at performance but to evaluate the blood status of vitamin D3 metabolites in pigs to determine if vitamin C supplementation could be beneficial.

The objectives of our studies were to evaluate the effect of a stabilized vitamin C on the performance and serum vitamin D3 concentrations in two groups of pigs: healthy and challenged.

Summary of Trials


The results of trial 1, which involved 488 pigs and 56 pens per treatment, are shown in Table 1. Pigs were fed grind-and- mix diets following Kent Nutrition Group NexGen starter programs.

The pigs were started on test on the day of delivery at about 20 days of age. The average initial weight was 13.03 lb. In this group of pigs, the health status was good, and we observed very small numerical responses to added vitamin C for the 34-day feeding period.

Table 2 shows the data from the group of pigs used in trial 2, where performance was poorer due to health challenges during the test period. In this test, there were 244 pigs and 28 pens per treatment, with an average initial weight of 13.51 lb. The pigs were fed the same starter programs as described for trial 1.

In all weighing periods, the addition of the stable form of vitamin C to the diets resulted in significant improvements in growth and economic performance.

For example, there was a 21% response in gain after 10 days on test, with an overall response in gain of 9% for the 34-day feeding period. Feed conversions were also improved with added vitamin C, which resulted in lower costs per pound of gain as well as a greater net return (value of gain minus feed cost) per pig of 27 cents at day 10 and 73 cents at day 34.

Since the initial one to two weeks represent a key period in which the nutritional status and performance of pigs must be improved postweaning, we chose to collect blood samples from eight pigs per treatment on day 11 postweaning to determine if dietary vitamin C would affect their vitamin C and vitamin D status.

On day 11, plasma vitamin C levels were 52.6% greater (1.16 mg versus 0.76 mg/ dL) for pigs fed the diet supplemented with vitamin C. Also on day 11, serum levels of 25-hydroxyvitamin D3 had increased 38.4% (10.02 ng versus 7.24 ng/ mL) for pigs fed vitamin C postweaning.

Figure 1

Figure 1 shows the serum measurements of 1,25-dihydroxyvitamin D3 on day 11. Pigs supplemented with vitamin C had a 14% increase in the serum levels of this key metabolite.

Figure 2

Furthermore, Figure 2 shows the data for 24,25-dihydroxyvitamin D3, which is another important vitamin D3 metabolite produced from 25-hydroxyvitamin D3 in the kidney. Note that supplemental vitamin C resulted in a 46% increase (P < 0.09) in 24,25-dihydroxyvitamin D3. Because vitamin D is important for facilitating the absorption of calcium, phosphorus and magnesium, having adequate levels of these metabolites is important for the optimum growth and development of tissues, particularly that of bones.


The data from these trials clearly show that supplemental vitamin C was very important for health-challenged pigs as it significantly improved gain, feed intake, feed efficiency and economics. Moreover, supplemental vitamin C resulted in a 14% increase in 1,25-dihydroxyvitamin D3 and a 46% increase in 24,25-dihydroxyvitamin D3, which are key metabolites made in the kidney from 25-hydroxyvitamin D3. The last four years have been extremely difficult in the swine industry with regard to soft bones and other various issues thought to be related to the vitamin D status of pigs. We believe that these findings are important in helping address this key area in swine production.

Based on this research, Kent Nutrition Group is introducing a new line of NexGen pig starters with NutriVantage technology that contains a stable form of vitamin C (Rovimix Stay-C 35).


Increasing the postweaning serum vitamin D levels with the use of a stabilized form of vitamin C is an important finding to help the pork industry make progress towards addressing the plethora of issues that may have been associated with vitamin D nutrition in postweaning pigs during the last four years.

In addition, marked improvements in gain, feed efficiency and economics from supplementation with vitamin C demonstrate that providing a dietary “margin of safety” for this vitamin may
be important for ensuring that health- challenged pigs have a better start during the postweaning period.

*Dr. Michael Edmonds is vice president, swine and poultry nutrition, for the Kent Nutrition Group. Dr. Jon Bergstrom is a senior swine technical support manager for DSM Nutritional Products in North America.