Conjugated linoleic acid can improve several pork quality traits, according to an Iowa State University study.

“The most consistent thing we see is more marbling and less fat,” says F.C. Parrish, Iowa State animal scientist. He notes that is contrary to most research and the Iowa State researchers are still looking for an answer. Some possibilities include blood flow and volume, or a shift in metabolic energy use.

There also was a tendency for the meat of CLA-fed hogs to have more of a reddish, pink color. The bellies were firmer, making them easier to slice – an important trait to accommodate bacon processing. All of these quality characteristics could contribute to increased domestic and international trade, says Parrish.

During the study, researchers added CLA to 0.75 percent of the total diet of 64 crossbred grow/finish pigs. The pigs were randomly assigned to receive a CLA-enhanced diet or control diets based on the animal’s stress genotype (negative, carrier or positive for the porcine stress syndrome gene). Parrish and the other researchers decided these genotypes are good models to study growth, color and other characteristics associated with stress and to determine if CLA has an effect on stress.

Iowa State animal and meat scientists used the data to analyze growth, carcass and meat quality data.

CLA did not affect the percent carcass shrink at 24 hours post-mortem. However, CLA-fed pigs had less 10th-rib fat depth and last-rib fat depth compared with control pigs. Loin muscle area was not affected by CLA supplementation, but it was significantly different according to the animal’s stress genotype. Stress-positive genotype carcasses had the largest loineye and stress-negative carcasses had the smallest.

Using the National Pork Producer Council's subjective lean color scores, researchers found that CLA did not affect lean color. However, color varied significantly with scores of 1.50, 2.40 and 3.1 for stress-positive, stress-carrier and stress-negative genotype. Subjective marbling scores increased significantly when CLA was added to the diet. Also, lean muscle firmness scores were higher for CLA-supplemented pigs and were correlated (0.92) to marbling scores.

These studies show that adding CLA to a pig's diet improves feed efficiency, reduces backfat and improves pork quality attributes of marbling and firmness.

Parrish notes that a lot more research is needed on CLA before you can start feeding it regularly. Cost is still a major drawback. Some estimates show using CLA would cost you $2 per pig marketed.