Organic selenium is showing superior results to inorganic selenium, reproductively, and especially in enhancing the selenium status of newborn and weanling pigs.
In research at Ohio State University, feeding organic selenium not only increased milk selenium content, but the resulting milk selenium also maintained a more constant level over several parities, offering progeny an advantage in survival and growth once weaned.
Selenium deficiency in high-producing sows still raises concerns in some regions, as does sudden postweaning deaths, which have been attributed to inadequate selenium.
Sodium selenite, or inorganic selenium, was approved at a supplemental level of 0.3 ppm in the early 1980s by the Food and Drug Administration (FDA). It is routinely added to most sow rations, and has reduced problems of deficiency, but problems persist in sows and pigs.
Organic selenium differs from the inorganic form in that the selenium is incorporated into a new amino acid form called selenomethionine; the product has been approved by the FDA.
Both forms of selenium provide enhancements to the sow and piglets, but research findings of the last few years suggest organic selenium adds 0.3 additional pigs/litter vs. inorganic selenium, improves sow health and reduces stillbirths.
However, its biggest benefit resides in its ability to more effectively transfer organic selenium to the developing fetus, resulting in greater selenium reserves in the newborn pig.
Figure 1 demonstrates that when levels of 0, 0.15 and 0.30 ppm selenium were fed to sows from both sources of the supplement, the newborn pig had greater body selenium contents when the sow was fed organic selenium.
The “C” mark on Figure 1 reflects a sow dietary treatment when a 50-50 blend of inorganic to organic selenium was fed. Results indicated there was no advantage to feeding 100% organic selenium vs. the combination of the two selenium sources.
Organic selenium not only is transferred more effectively to the developing fetus, it is also effectively transferred to the milk of lactating sows.
In the four-parity study, Figure 2 shows that when females were fed a non-selenium-supplemented diet, milk selenium concentration was highest in young gilts and declined with ensuing parities, reflecting the loss of body selenium over time.
When inorganic selenium was fed, there was a small boost in milk selenium from the base 0.15 ppm to 0.3 ppm, but still a decline in milk selenium with later parities. In contrast, when organic selenium was fed, milk selenium levels were higher and remained relatively constant throughout the four parities.
This research suggests that the addition of organic selenium is clearly more beneficial to both gestating and lactating sows, and in enhancing the selenium status of pigs at weaning.
Researcher: Don Mahan, Ohio State University. Contact Mahan by phone (614) 292-6987, fax (614) 292-7116 or e-mail mahan.3@osu.edu.