Canadian researchers found supplementing finishing hog diets with the anti-oxidant vitamins E and C resulted in color stability, reduced drip loss and reduced lipid oxidation in fresh and cooked pork. Researchers from the University of Guelph, Ontario, Canada, discovered gilts responded more positively in most variables tested than barrows did when fed supplemental vitamins.

Studies of vitamin E in market hog diets show a benefit in color, drip loss and lipid oxidation. Supplementation time and levels for many studies have been varied, and no concise recommendation has been developed, the researchers say. There also is no research on the additive effects of vitamin E and C supplementation on pork quality.

Vitamin C is a well-known, free radical scavenger, and has been shown to improve lipid stability in beef. Vitamin C also reduces the alpha-tocopheryl radical, thereby regenerating vitamin E.

Experiments were conducted to determine what effect the addition of vitamins E and C in the diets of market hogs have on the dressing percentage, color and drip-loss of fresh pork, and the lipid oxidation of fresh and cooked pork and cooking loss.

The studies were conducted at Ridgetown Swine Research Center. Three-hundred, commercial, crossbred market hogs were used to test the effects of different levels of vitamin E. The levels tested were control, 200 IU/kg. (90.91 IU/lb.) or 400 IU/kg. (181.82 IU/lb.) of feed supplementation level. The diets were fed for three weeks before slaughter, and treatments of 400 IU (181.82 IU/lb.) of vitamin E plus 500 mg. (227.27 mg./lb.) vitamin C per kg. of feed fed for either two or three weeks before slaughter.

Barrows and gilts were penned separately. All animals were slaughtered at approximately 231 lb. of body weight.

The loin was removed from one side of the carcass after a 24-hour chill. A 48-hour drip loss and color (Minolta Chroma-Meter) measurement were determined on duplicate cores of longissimus muscle. Fresh loin roasts were weighed, cooked and re-weighed and packaged under normal retail lighting conditions for analysis at 24 hours and 144 hours after cooking. Core samples of the roasts were taken fresh and at 24 hours and 144 hours after cooking to test for lipid stability.

Vitamin supplementation had no effect on the dressing percentage of the hogs. Drip loss was not significantly different across treatments. However, hogs fed for two weeks with vitamins E and C had 6.6% lower drip loss than control hogs. (10.5 +/- .35 versus 9.8 +/-.35% drip loss for control and vitamin E and C treated, respectively).

There was no effect of treatment on the color of barrow meat. The color of gilt meat was shifted further into the red range of the color spectrum with vitamin E and C treatment fed for two weeks. There was no effect of vitamin E fed alone at either level on the lipid oxidation of fresh or cooked pork. However, there was a significant effect of lowering lipid oxidation when vitamin C was added.

Treatment had no effect on cooking loss, however, gilts treated with vitamins E and C for both supplementation times had 2% lower cooking loss than barrows.

The researchers say pork quality is influenced by many variables and the repeatability of measurements is a concern. Split-sex feeding may be necessary to take advantage of the benefits of vitamin supplementation.

Vitamin C may well be an important partner with vitamin E in preserving cooked and/or processed pork. Future research will focus on optimizing the amount, delivery (feed or water) and supplementation time needed to create a cut of pork that provides an effective source of antioxidants in addition to a high quality, palatable source of protein.

Researchers: Vernon R. Osborne, Ridgetown College, Roger R. Hacker and E. Jim Squires, Department of Animal and Poultry Science, University of Guelph. Contact Hacker at (519) 824-4120.