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Researchers Explore Possible Changes in Body Composition of Future Pigs

By Jill Lee
May 21, 1999

Two natural animal hormones are critical to developing fat cells in fetal pigs. One increases the number of fat cells; the other makes fat cells bigger. They work best together, say researchers--and knowing this may someday make leaner pork possible.

The scientists, with the Agricultural Research Service, found these hormones of the thyroid and adrenal glands work in tandem to give fetal pigs the sustaining layers of fat they will need after birth.

The thyroid hormone increases fat cell numbers; the adrenal one increases their size. Together they allow for a greater increase in fat than either hormone alone, according to the lead researcher, animal physiologist Gary J. Hausman. He's at the Animal Physiology Research Unit of ARS’ Richard B. Russell Agricultural Research Center in Athens, Ga.

Hausman and colleagues studied the role of these hormones by treating fetal pigs with thyroxine (a thyroid hormone) or hydrocortisone (an adrenal hormone) at various stages of gestation. Other fetal pigs received both hormones. Results showed the hormone combination caused more fat deposition than either hormone alone.

The study results suggest the potential for an opportunity for producing leaner pork by reducing levels of one of the hormones in a fetal pig or piglet. The scientists reason that since the hormones' combined activity accelerates fat gains, restricting their “partnership”--by limiting one of the hormones--might reduce the fat gains. This might be done by breeding or through treatments as the piglet grows.

By understanding the biology of fat hormones, the researchers hope to learn more about reducing fat in pork. This information could also be useful to medical researchers seeking to understand factors contributing to obesity in humans.

ARS is the chief scientific agency of the U.S. Department of Agriculture.

Scientific contact: Gary Hausman, ARS Richard B. Russell Agricultural Research Center, Athens, Ga., phone (706) 546-3584, fax (706) 546-3586,