Increasing vitamin D intake for enhanced sow performance

Swine are considered more profitable when sows and gilts produce more, healthy piglets over their lifetime. In recent years, the number of additives available on the market has increased and, as a result, swine farmers have a growing number of nutritional options available to them to help maximize animal productivity and profitability by making the most of the animal’s genetic potential.

One particular additive that is receiving growing interest is vitamin D3. Although typically used to support skeletal strength and bone health, the latest research shows that enhanced vitamin D3 nutrition can also positively influence sow performance and lifetime output. For example, not only do increased levels lead to longer lives, but several studies also demonstrate an increased number of heavier and weaned piglets per litter in sows which are receiving optimized nutrition. As a result, farmers are beginning to recognize vitamin D3 as a broader solution to ensure breeding sows achieve their full potential and increased financial return.

Measuring profitability in swine

Previous studies indicate that low-birthweight piglets exhibit poorer growth performance, decreased productivity and higher mortality pre-weaning – a major cause of profit loss in pig production – whereas piglets born with higher birth weights are more likely to experience better performance and decreased mortality. To achieve better profitability, farmers must therefore keep sows in the herd for more parities so that they produce more piglets over their lifetime, and also ensure sows produce larger litters of healthy piglets with high birth and weaning weights.

However, to accomplish optimum genetic potential and produce the healthiest piglets possible, sows require more and better-quality nutrition including vitamin D3 supplementation. However, adding vitamin D3, a non-bioactive vitamin, directly to feed presents multiple challenges. That is because it must be metabolized to its functional form to become active in the body and have the desired effect. In a first step, vitamin D3 is broken down to 25(OH)D3 in the liver. The final compound, 1,25(OH)2D3, or calcitriol, is then formed in the kidneys. In many hyper-prolific sows however, the first metabolic step tends to be skipped, meaning vitamin D3 is not always fully transformed to its bioactive form, which decreases the amount of effective vitamin available to the animal, and could lead to leg problems, as a result of lowe bone mineralization, less foetal muscle development and decreased muscle contractions during birth. Consequently, farmers may observe lower herd performance and reduced profitability.

As a result of these drawbacks, farmers are now looking to Hy-D (or 25OHD3) – the bioactive metabolite of vitamin D3 – for increased vitamin nutrition, healthier piglets and better financial returns.

Enhancing vitamin D3 availability

To increase the amount of vitamin that is readily absorbed and utilized by the pig, swine farmers can add the active form of vitamin D3 to sow feed and therefore avoid the initial metabolic steps normally involved in the breakdown of the nutrient. SEGES – the Danish Pig Research Center, Denmark – recently conducted a study in a commercial herd of 650 sows/year, to determine whether adding 50mg/kg of Hy-D in sow feed (corresponding to 2,000 IU vitamin D3) during the entire gestation period would improve litter weaning weight compared to when standard levels of 800 IU per kg feed were added. Other key indicators of swine profitability where also evaluated including daily gain and mortality to assess whether Hy-D positively affected weaners born and raised by sows supplemented with the ingredient.

Graph 1: Litter weight at weaning in control and Hy-D groups. Largest increase seen in younger sows (1-2 parity)

The study found that Hy-D had the greatest effect in young sows. It also demonstrated that litter weight was significantly increased in the group fed the bioactive vitamin – researchers recorded a weight of 19.8kg in sows who were feed Hy-D, compared to 18.8kg in the control group. As litter gain was used as an indication of milk production in sows, this suggested that the Hy-D group had increased milk efficiency. In addition to litter weight, Hy-D also had a positive effect on weight at weaning. Data showed that piglets were 3.6kg heavier at weaning where sows were supplemented with the bioactive form of the vitamin (Graph. 1). As weaning weight was higher, the results indicate that Hy-D had a positive effect on reproductive efficiency by helping sows to farrow quicker, have healthier, better performing and longer living piglets. This was confirmed with the higher number of piglets weaned by the Hy-D group.

Optimizing vitamin D3 status

The SEGES study clearly demonstrates that optimized vitamin D nutrition can be achieved via Hy-D supplementation, and when vitamin levels are maximized, swine reproductivity and performance improves, contributing to increased farm profitability.

It showed that Hy-D was much more efficient at increasing vitamin levels than vitamin D3. For instance, sows fed the Hy-D form of the vitamin throughout their reproductive lifecycle exhibited 25(OH)D3 levels in blood plasma were double, despite the equivalent dose of vitamin D3 (2,000 IU per unit feed) being used in the control group (Table 1). Table 2 further illustrates that 25(OH)D3 concentration in the blood at the time of farrowing was 2.3 times higher in sows fed bioactive Hy-D for two weeks compared with sows supplemented with regular vitamin D3. In sows fed Hy-D for seven weeks, the concentration of 25(OH)D3 in sows’ blood was 46.7ng/ml i.e. 3.2 times higher than the control group.

Table 1: The effect of treatment on blood content of 25(OH)D3 during lactation
Table 2: The effect of the treatment period on blood plasma content of 25(OH)D3

A second study showed similar results in 90-day old foetuses, demonstrating an increase in vitamin D3 status when Hy-D was added to gilt gestation feed compared to using commercial vitamin D3. The researchers also observed an increase in the foetuses’ total number of muscle fibres (9.3% increase) which is a strong indicator of healthy, strong piglets.

Finally, the SEGES paper confirmed that litters were larger and litter weight was higher when gilts were given Hy-D. And, further trials have highlighted the positive effects of Hy-D on a number of other essential functions in swine including reproduction, muscle development and immune response modulation – all important factors contributing to improved performance and overall profitability.


It is clear that vitamin D3 plays a key role in sow performance, sustainability and profitability, as well as piglet health and growth. However, the latest research strongly supports the idea that significant economic value is created when feeding sows Hy-D (the most bioavailable form of vitamin D), rather than using vitamin D3 directly because it improves vitamin D status. That is because Hy-D ensures more efficient and faster uptake of the required metabolite 25(OH)D3, resulting in a stronger skeleton and healthier, more productive animals and healthier piglets as a result – the key to increased herd profitability.

Published on

04 September 2019


  • Vitamins
  • Swine


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