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Gwaltney Gift Creates Unique Opportunity to Study Pork Quality

Livestock Update, January 1997

Allen Harper, Extension Specialist, Swine, Tidewater AREC

The Gwaltney name has been associated with fine Virginia pork products for over 100 years. This tradition continues today with the Gwaltney of Smithfield plant producing and marketing a variety of pork products throughout the United States. A recent financial gift by Mrs. Henrietta C. Gwaltney, a member of the family that founded the Gwaltney packing plant, has provided a unique opportunity to fund useful research for the pork industry.

An interdepartmental team of faculty consisting of Cindy Wood (Animal and Poultry Sciences), Jim Claus (Food Science and Technology) and Allen Harper (Tidewater Agricultural Research and Extension Center) has the responsibility of developing and conducting a project which focuses on the gift's intent of beneficial "swine improvement research." Brent Green, a recent graduate of Animal Science at Kansas State, is also working on the project as part of his master's degree program.

The project seeks answers on two important swine industry concerns. First, market pigs that are carriers of the "stress gene" (also referred to as Halothane 1843 carrier pigs) are known to produce carcasses with less external fat and heavier muscling than their non-stress gene contemporaries. However, research also suggests that stress gene carrier pigs may produce pork cuts that are paler in color and subject to shrinking and excess drying when processed and cooked. Currently there is debate in the industry as to whether the stress gene should be strategically used to produce leaner carcasses or totally eliminated by selection to avoid possible pork quality problems.

Our project will involve breeding approximately 24 sows for two consecutive farrowings to produce at least 160 test pigs. These terminal market pigs will be sired by full-sib stress gene carrier boars, making them genetically similar in all respects except that half of the pigs will be stress gene carriers and half stress gene free. This approach will provide an opportunity to accurately evaluate effects of the stress gene on pig performance, carcass fat and lean content, and pork muscle processing quality.

A second component of the project is to evaluate addition of trace mineral chromium to the mineral supplement for both genotypes of pigs. Feeding and carcass evaluation trials at Virginia Tech and other land-grant universities have shown some improvement in feed conversion, backfat depth and muscling with chromium supplementation from an organic chromium source called chromium picolinate. This product was recently approved by FDA as safe to include in swine feeds. But, there is still a deficiency of information on how the product may impact pork processing and cooking qualities or performance of market pigs sired by extremely lean, stress gene carrier boars.

In November of 1995, the project got underway with the artificial mating of 28 sows at Tidewater AREC swine unit in Suffolk. Semen was collected for these matings from 2 littermate stress gene carrier boars at a commercial boar stud in Michigantown, Indiana. From the litters produced by these matings, a portion of each piglets' docked tail was assayed under the direction of Eric Wong at the Animal and Poultry Sciences Biotechnology Lab to determine stress gene carrier status. Once stress gene status was established, feeding trials were conducted followed by carcass and muscle quality evaluations at the Food Science and Technology Meats Lab. This same process is currently being repeated on a second set of pigs produced by the same stress gene carrier boars. Overall results of the study will be available in late Spring of 1997.

This effort is unique in that it will provide beneficial information that can impact the complete process of pork production, from conception to processing of edible product. We are excited about this collaborative effort and about the valuable information it will provide to the swine industry. We are also appreciate of Mrs. Gwaltney's gift which makes it possible.

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