And, as such, certain polyphenol blends may be better suited for managing oxidative stress than Vitamin E as the impact of the vitamin easily saturates at high dosage levels, said the animal feed specialists.
Low free radical levels are needed for high performance, but an increase in such levels leads to disease in livestock.
We talked to Dr Peter Ramaekers, project manager for pig nutrition at Nutreco, during VIV Europe, and heard about the Dutch feed firm's research into managing oxidative stress in animals.
He said certain fruit, vegetable or herb derived polyphenols can partially replace vitamin E in feed, in that they have a similar molecular structure to the vitamin but greater anti-oxidant capacity.
“Vitamin E has a long lipophilic tail and thus less anti-oxidant capacity per gram than some polyphenol blends,” said Ramaekers.
Anti-oxidant defenses at cell level
Theo van Kempen and Hubert van Hees from the Swine Research Centre at Nutreco, along with researchers from Ghent University in Belgium, found a polyphenol blend containing curcumin and rosmarinic, among others, was effective in lowering oxidative stress in heat-stressed piglets.
Writing in last month’s edition of the Journal of the Federation of American Societies for Experimental Biology, the researchers described how they tested these on newly-weaned piglets.
The young pigs were first put on diets devoid of vitamin E for 18 days.
They were then fed diets containing either 11 IU vitamin E (control), 80 IU vitamin E (80E), or 11 IU vitamin E with a 69 IU vitamin E equivalent provided by a polyphenol blend (PB) containing rosmarinic and carnosic acid, curcumin, resveratrol, and naringenin.
The authors said that seven days later the piglets were submitted to heat stress known to induce oxidative stress: 40°C for 24 hours, flanked by blood sampling.
Prior to being exposed to heat stress, plasma superoxide dismutase (SOD) was lower for PB than the controls while 80E was intermediate. The ORAC value was highest in PB and lowest for 80E, they said.
Following heat stress, the authors found that malondialdehyde (MDA) was lowest in the polyphenol blend, intermediate in 80E, and highest in the controls.
MDA is a well-known secondary product of lipid peroxidation after exposure to reactive oxygen species and free radicals, and can be used as an indicator of cell membrane injury.
“In conclusion, the polyphenol blend offered at least as good a protection against oxidative stress in heat-stressed piglets than a high dose of Vitamin E,” said the researchers.
Immune boosting effect questioned
However, DSM says it has clearly been documented in scientific papers that polyphenols are not sufficiently absorbed, and thus it is not possible that they could be used to replace vitamin E.
"Even if found in muscle cells, the active concentration would be much lower than necessary to provide antioxidant protection. The absence in cells also implies that polyphenols cannot have any effect on immune stimulation and reproduction," said the company in a Q and A on its website.