Swine Genetics

Market Quality

The point of raising a market hog is to produce the highest quality hog possible. To achieve the highest quality, you must first understand proper management techniques and nutrition.

With that said, there are some other factors to producing quality swine. The genetic background of the market hog plays a major role. If your project pig has parents with poor structural quality, it will take much more work and time, to get your project pig up to market standards. It is also possible, that this level of quality will not be reached. Now you can see why it is important to check the quality of your project hog, paying close attention to it’s parents. Some hogs have what is known as Porcine Stress Syndrome (PSS) which is a stress gene. This gene causes heavy muscles and less fat, but also creates tougher lower quality meat. Stay clear of this gene as the meat will be watery and light colored.

Through years of research and quality control, there are recognizable characteristics that are graded nationally. We will go over these traits and discuss the grades of pigs as defined by the government. This should give you some good insight into swine genetics and allow you pick a project pig with desirable characteristics.

The Gene Pool

Advances in swine genetics and technology, have allowed the swine industry to identify the genes that directly affect muscle quality. These genes are responsible for poor muscle quality, like bad coloring, firm/wet, and negative marbling. These traits are undesirable to consumers, processors, and swine packing plants. Knowledge of these genes is essential to the swine industry and for your project hog.

Porcine Stress Syndrome (PSS)

Porcine stress syndrome (PSS) is also known as the stress gene. PSS is an inherited recessive condition in swine. Pss has been identified predominately with the Pietrain breed. Pigs who carry two copies of the PSS gene are classified as “Stress Positive” and are titled as “nn” genotype. The stress positive “nn” pig, is susceptible to external stress from environment, movement, and mixing. Any of these elements can cause death loss in a stress positive “nn” herd. Stress positive “nn” pigs also produce “Pale, Soft, and Exudative” (PSE) carcasses more than 90% of the time. A normal pig is titled “NN” and a pig that is only a carrier of the PSS gene is titled “Nn”. Stress carriers (Nn) are not susceptible to death due to stress, but they due produce PSE pork 30% to 60% of the time. Obviously we all want to strive for NN normal pigs that will produce higher quality pork and lower percentages of PSE.

There is a gene test available for the PSS condition. The test will identify nn and Nn pigs. These pigs should be avoided due to poor muscle quality. The National Pork Producers Council put guidelines in place for the removal of PSS pigs to insure the quality of U.S. pork production.

Rendement Napole Gene

Swine that inherit the “Napole Gene” can either be carriers (RN-,rn+) or positive (RN-,RN-). This gene causes undesirable muscle traits, and and been identified and associated with the Hampshire breed of swine. When the Napole gene(RN-) is present, the meat will have poor water holding capacity(WHC), a low ultimate PH, high moisture loss when cooking, and poor processing characteristics. As with (PSS) the Napole gene(RN-) can be tested for, using a DNA test. The RN- gene is a major concern to producers, since it directly associated with Hampshire hogs and Hampshire crossbreeds. By testing for this gene, pork producers can select pigs with or without RN- gene.



  1. Barrett says:

    Do pig farmers make pretty good money or do you do it just for fun?

    • Matt says:

      Barrett, you can make money pig farming. It takes quite a few hogs to get to that point and a rigorous breeding schedule for production. We enjoy the pigs, so we are not trying to get rich from pig farming.

Speak Your Mind