A recent Ohio State University study compared the use of an enriched selenium yeast (1000 ppm) or sodium selenite added to sow diets when they entered the farrowing house, or approximately 5-6 days prior to farrowing.
Although the FDA has approved the use of selenium in the forms of sodium selenite or selante in swine diets up to a supplemental level of .3 ppm, deficiencies of vitamin E and selenium still occur in many of the nation's swine herds. This deficiency seems to be more common in parts of the U.S. where the grain content of selenium is low. However, deficiencies also occur in the progeny of older, higher-producing sows.
The characteristics of neonatal pigs affected by a selenium deficiency are weakness, lack of desire to nurse the sow, mulberry heart and the occurrence of iron toxicosis. The latter condition is noted when neonatal pigs go into shock and die when given a 100 to 200 mg. injection of iron to prevent anemia.
Perhaps the period when the selenium deficiency is most prevalent in young pigs is within a few weeks upon weaning, where the largest, fastest-growing pigs suddenly die with no outward symptom. A recent summary of milk selenium contents by Ohio State University (OSU) scientists has documented that the milk selenium content of sows declines as they mature, thus providing less selenium to the pig upon birth and at weaning.
The OSU research trial used a total of 45 sows. The sows were fed diets with either .15 or .30 ppm inorganic or organic selenium. In addition, a non-fortified diet (basal) and a diet with a combination of the selenite and organic yeast product were fed in a 50:50 blend. Each blend provided .15 ppm selenium for a total of .30 selenium in the sow's diet..
The results, presented in Figure 2, demonstrate that the sodium selenite resulted in a small increase in the milk selenium content of the sows, but the incorporation of the organic selenium from the yeast resulted in a dramatic increase in milk selenium content.
The combination of both selenium sources produced milk selenium results that were similar to those when the organic selenium source was fed. This suggests that the inorganic form of the mineral was not effectively transferred to the mammary tissue and thus the milk supply of the nursing pig.
Other data demonstrates the blood selenium content of the pigs' blood was higher when the organic selenium was fed to the sow, thus improving their status at the time of weaning. Although the use of organic selenium has not been approved for use by the FDA, its approval is expected by early 1999.
Researcher: Don Mahan, The Ohio State University, Columbus, OH. Phone Mahan at: (614) 292-6987.