Excess DDGS not cause of mulberry heart disease in pigs
Since DDGS is a relatively new feed ingredient being added to swine diets in large quantities (30 -40%), it’s become an easy target to blame for a variety of evolving pig health and performance problems.
DDGS use has dramatically increased over the past 10 years, predominantly because of rapid increases in supply and availability, as well as an opportunity to substantially reduce diet cost by replacing some of the corn, soybean meal and inorganic phosphate in swine diets.
During the past few years, swine veterinarians have reported observations of what some perceive as an increasing trend of mulberry heart disease (MHD) in nursery pigs.
MHD is a classic nutrient-deficiency disease caused by inadequate vitamin E and/or selenium in swine diets. It most commonly causes sudden death of fast-growing nursery pigs within a few weeks after weaning.
However, there are no published data indicating that MHD is increasing in US swine herds, nor are there any clear trends from University of Minnesota and Iowa State University Veterinary Diagnostic Laboratory reports over the past five years.
But that does not mean it is or is not a concern and why is DDGS being targeted?
Lipid peroxidation and sulphur
The sulphur concentration and lipid peroxidation levels varied widely among sources, but on average, DDGS had much greater levels of both oxidized lipids and sulphur compared to a corn reference sample.
It’s well known that DDGS contains high levels of linoleic acid, a long-chain polyunsaturated fatty acid that’s easily oxidized.
Several published research studies have shown that feeding oxidized fats or oils to pigs reduces growth performance.
Therefore, when the pig’s antioxidant capacity is diminished by feeding diets high in oxidized lipids or polyunsaturated fats, there may be an increased need to supplement antioxidants, such as vitamin E.
Finally, sulphur has been shown to interfere with selenium utilization, which could further reduce the pigs’ metabolic oxidation status.
Vitamin E effect
DDGS is not a factor, but supplemental Vitamin E is. Feeding DDGS to pigs did not change the serum vitamin E concentration of pigs in the nursery, but adding 5x the vitamin E requirement did improve antioxidant status (vitamin E) in the late-nursery period.
Regardless, high DDGS levels can be fed to pigs and sows without the risk of developing MHD or reducing pigs’ antioxidant status post-weaning.
Feeding DDGS appears to improve the pig’s metabolic oxidation status, because sulphur is an integral component of glutathione, and the increased levels of these sulphur-containing antioxidants likely counteracted or masked any effect of oxidized lipids in the DDGS diets, leading to a sparing effect on vitamin E.