By: Gregg Rentfrow, University of Kentucky


Raising heritage pig breeds is becoming a popular niche market. Farmers are using more historical management and feeding strategies to create a unique product. To capture the full economic value of the animal, most heritage pork is marketed through on-farm and/or farmer’s market sales, or to white table cloth restaurants.  Federal laws and regulations must be followed to sell meats. In addition, heritage pig carcass yields are different when compared to traditional market hogs. Understanding the laws and the carcass differences will aid farmers in decision making when it comes to meat processing.

Meat Inspection

Chicago’s Union Stockyards and Transit Company opened its doors in 1865, signifying the beginning of the modern livestock and meats industry. The spirit of the original business model, along with some of the techniques developed at Union Stockyards, are still practiced today. Union Stockyards’ most significant contribution is the Federal Meat Inspection Act. Author Upton Sinclair penned a book called The Jungle in 1906, which described some unappetizing methods used by the industry.  Public outrage forced the U.S. government to pass the Federal Meat Inspection Act of 1906, which mandated that all meat intended for interstate commerce be inspected by the government. Basically, all meat and meat products intended for sale must be inspected, regardless of the size of the farm or the amount of product sold. No exceptions. The meats industry still operates under the heart and soul of the original document; however, the original Federal Meat Inspection Act and new acts and regulations are continually being added and up-dated.

Meat inspection, in general, is designed to ensure the wholesomeness of fresh and processed meats. The inspector oversees the humane handling and slaughter of the live animals, verifies that the meat is fabricated and processed in a clean, sanitary environment, and that all meats and meat products are properly labeled. There are three types of meat processors: federally inspected, state inspected, and custom.

Federal and State Inspection   

The United States Department of Agriculture – Food Safety and Inspection Service (USDA-FSIS) provides federal meat inspection. Fresh and processed meats made under federal inspection can be sold in all 50 states, and will display the round inspection legend on each package.

Meat Inspection Stamp

Traditionally, state departments of agriculture provide state meat inspection services. State meat inspection must be equal to or better than federal inspection.  Fresh and processed meats from state meat inspected plants can only be sold within said state. For example Missouri inspected meats can only be sold in Missouri and not in Illinois, Iowa, Kansas, etc. Working with state inspected meat plants can limit the market for heritage pig farmers, especially those close to a state borders or those selling via mail order. Normally, state inspection legends are in the shape of the state, rather than the round USDA inspection legend. A listing of states and contacts within those states can be found at:

Custom Processors

Custom processed meats cannot be sold legally. The vast majority of meat processors are custom operators. The farmer pays the custom meat processor to slaughter and fabricate the animal, which is stamped ‘Not for Sale’, and the meat is intended to be consumed by the owner of the animal. Selling custom processed fresh and processed meats is illegal.

State and Local Health Departments

On-farm sales and farmer’s markets are common venues to sell local meats. The local and/or state health department should be notified before selling meat off the farm. The health department wants to make sure only inspected meats are sold, as well as evaluate how it is packaged, labeled, and stored. Furthermore, most organized farmer’s markets have rules that must be followed. Farmer’s markets will follow the aforementioned rules, assuring that frozen meats stay frozen and refrigerated meats stay cold throughout the sales day. Contact the farmer’s market organizers for specific rules.

Working with meat processors

The heritage pig farmer/direct marketer may find working with meat processors to be challenging. Most meat processors may be booked months in advance, which is a common complaint. Some meat processors will work with direct marketers to establish a recurring appointment on the slaughter schedule, but processing needs will have to be communicated clearly to the processor.

Meat processors have their own language and assume you understand the vocabulary. Not knowing the terms can be frustrating; below are a few of the most common terms:

Dress or Dressing Percentage – the percentage of the hot carcass weight in relation to live weight, or how much of the live pig is left hanging as a pork carcass (Hot carcass weight ÷ Live weight) x 100). The average pork carcass dressing percentage will be around 70% of the live weight. The dressing percentage can be affected by gut fill, time the live weight was recorded (pigs can lose 10+lbs overnight), and the amount of fat/muscle.

Shrink – due to evaporative cooling, carcasses can lose 3 to 5% of the hot carcass weight during the first 24 hours. Meat is 70 to 75% water, which makes it susceptible to evaporative loss. Fat on the carcass acts as insulation/protection against shrink, therefore fatter carcasses are more protected and may be expected to shrink less during cooling.

Yield – the amount/percentage of retail product from the carcass; i.e., after you cut the carcass into what you would put on the plate (remove spine, excess fat etc.), what’s left?

Trim loss or cutting loss – the amount of the carcass weight lost during fabrication.  Fatter carcasses will have a higher cutting loss. And heritage breeds of pigs tend to be fatter than traditional breeds, there will be a higher trim loss. This can be thought of as the opposite of Yield.

The quality of the retail cuts is another common complaint when working with processors. Most USDA inspected facilities have a retail sales area. The quality and/or craftsmanship of the cuts on display are a reflection of what you will receive. Open communication is the key to a healthy working relationship. If you are not happy with the quality of the work, discuss your frustrations with the meat processor and give them the opportunity to rectify the problem. Take time to choose a meat processor you can work with.

Carcass Quality Characteristics and Yields

Decades of genetic selection have created a faster growing, leaner modern pig.  However, the growth and carcass characteristics of heritage breeds of pigs are different; below are tables comparing some genetic sources. Research conducted at the University of Kentucky and Berea College evaluated characteristics of various heritage hog breeds.

Eight heritage pig breeds (n = 7 per breed; Guinea, Hereford, Large Black, Mulefoot, Gloucestershire Old Spot, Ossabaw, Red Wattle, and Tamworth) were raised outdoors on 1.5 acres of fescue pasture, along with other grasses and broadleaf weeds, at Berea College (Berea, KY).  Deep-bedded hoop structures (n = 3) were provided to protect animals from the elements. Pigs were provided a diet consisting of ground corn, soybeans, and Fertrell swine premix (Bainbridge, PA), along with water, ad libitum.

Pigs were transported to the University of Kentucky Meat Science Laboratory (Lexington, KY; approximately 45 miles) for humane slaughter under USDA–FSIS inspection. Carcasses were allowed to chill (38°F) overnight before carcass data were collected on the lefthand side of the animal (last lumbar, last rib, and first rib backfat depth, along with 10th rib backfat and loin eye area) (Table 1).  Carcasses were fabricated into fresh wholesale cuts according to Institutional Meat Purchasing Specifications (IMPS); Boston Butt (IMPS 406), Picnic (IMPS 405), Loin (IMPS 410), Sparerib (IMPS 416), Belly (IMPS 408), and Ham (IMPS 401; Table 3). Note that carcass measurement and yields are averages of seven animals per breed; data have not been statistically analyzed for comparison.

Table 1. Carcass characteristics of eight heritage pig breeds (n=7/breed).

Breed HCWT1 1st Rib FD2 Last Rib FD2 Last Lumbar FD2 10th Rib FD2 Loin Eye Area3 %Muscle4
Guinea 140.4 3.11 2.13 2.2 2.5 2.9 24
Hereford 252.1 2.19 1.91 1.66 1.99 6.8 42
Large Black 229.4 2.66 2.07 2.61 2.66 4.2 32
Mulefoot 208.8 2.55 1.87 1.82 2.18 4.18 36
Old Spot 156.0 2.05 1.40 1.20 1.25 5.3 46
Ossabaw 187.9 3.49 2.03 2.16 2.53 4.3 31
Red Wattle 223.8 2.75 1.92 2.07 2.12 4.53 37
Tamworth 231.0 2.09 1.59 1.41 1.81 6.09 43
1 HCWT, Hot Carcass Weight, lbs.
2 FD, Fat Depth, measured in inches.
3 Loin Eye Area, measured in square inches at the 10th/11th rib interface.
4 % Muscle, (7.231+(0.437*HCWT)-(18.746*10th Rib FD)+(3.877*LEA))/HCWT.

Table 2. Pork loin eye quality data evaluated at the 10th/11th rib interface.

Breed Color1 Marbling2 Firmness3 L*-value4 a*-value4 b*-value4
Guinea 3.4 5.1 3.5 55.40 9.25 14.24
Hereford 3.6 2.7 3.5 55.36 10.72 15.16
Large Black 3.7 3.1 3.7 54.26 10.33 14.81
Mulefoot 3.5 3.1 2.7 45.08 9.34 12.99
Old Spot 3.7 2.8 3.7 56.96 7.88 14.86
Ossabaw 4.7 2.7 4.0 58.98 11.67 11.98
Red Wattle 3.0 4.0 3.7 55.77 9.74 14.78
Tamworth 3.7 3.1 3.6 57.71 9.52 17.41
1Color (NPPC), 1=Pale pinkish gray, 2=Grayish pink, 3=Reddish pink, 4=Dark reddish pink, 5=Purplish pink, Dark purplish red.
2Marbling (NPPC), subjective measurement of the percentage of marbling within the loin eye.
3Firmness (NPPC), 5 point scale where 1=soft to 5=very firm.
4CIE L*-value 0=black, 100=pure white, a*-value measure of red (+) to green (-), b*-value measure of yellow (+) to blue (-).

Table 3. Pork carcass wholesale cut yields by breed.

Breed Boston Butt (lbs)1 Picnic (lbs)2 Loin (lbs)3 Sparerib (lbs)4 Belly (lbs)5 Ham (lbs)6
Guinea 3.89 5.4 9.34 1.78 14.49 11.66
Hereford 9.14 11.66 22.56 3.99 20.85 26.91
Large Black 7.42 9.50 19.86 2.76 18.90 21.22
Mulefoot 6.63 8.71 13.02 3.59 17.77 20.05
Old Spot 6.95 6.68 13.35 2.98 9.33 16.10
Ossabaw 5.37 8.29 13.81 2.77 18.26 16.01
Red Wattle 7.00 7.88 13.89 3.73 19.19 21.43
Tamworth 8.44 11.08 21.06 3.68 18.34 23.93
Wholesale cuts fabricated according to Intuitional Meat Purchasing Specifications (IMPS).
1Boston Butt = IMPS 406, 2Picnic = IMPS 405, 3Loin = IMPS 410, 4Sparerib = IMPS 416, 5Belly = IMPS 408, 6Ham = IMPS 401.

Among the heritage breeds, the Guinea hogs were the smallest framed breed in the study, which explains why they had the lightest hot carcass weight. Furthermore the Guinea breed was the fattest at all depots and the lightest muscled, as indicated by the percentage of muscle. The Old Spot (Gloucestershire Old Spot), Tamworth, and Hereford were the only breeds with a percent muscle above 40%; industry average for commodity breeds is around 50%. The NPPC color, marbling, and firmness scores, along with L*, a*, and b*-values, are within industry averages for all breeds evaluated. The wholesale yields are an average for the breeds evaluated in this study and should only be used as a guide for how much to expect from the meat processor.

Table 4. Carcass characteristics from conventional maternal swine genetic lines mated to Duroc boars, for comparison.

Breed HCWT1 10th Rib FD2 Loin Eye Area3 % Muscle4
ADSG 189.6 0.94 6.4 51.2
DB 191.8 0.79 7.0 50.1
DK 191.8 0.91 6.7 53.9
GPK347 185.2 0.91 6.4 55.2
NH 187.4 0.79 6.8 53.7
NSR 189.6 0.87 6.6 52.4
1 HCWT, Hot Carcass Weight.
2 FD, Fat Depth, measured in inches.
3 Loin Eye Area, measured in square inches at the 10th/11th rib interface.
4 % Muscle, (7.231+(0.437*HCWT)-(18.746*10th Rib FD)+(3.877*LEA))/HCWT.
Adapted from Cassady et al., 2004, percentage of muscle calculated from reported averages.
ADSG = American Diamond Swine Genetics (Prairie City, IA), DB = Danbred USA (Seward, NE),
DK & GPK347 = Monsanto Choice Genetics (St. Louis, MO), NH = Newsham Hybrids
(Colorado Springs, CO), NSR = National Swine Registry (West Lafayette, IN; Landrace x Large White).

Table 4 shows the results of the National Pork Producers Council maternal line genetic evaluation study (Cassady et al., 2004). Pigs were fed a traditional corn – soybean meal diet and penned by sex, rather than breed. The pigs were harvested when the pen live weight averaged 253 ± 13 lbs. The pigs were on test for 75 ± 17 days, and the carcasses were allowed to chill for 24 hours before carcass measurements were taken. These data are provided to give an idea of how the heritage breeds differ in carcass composition from commodity pigs. This will be valuable to understand as you work with the meat processor and with your customers.

Packaging and Labeling

Historically, fresh meats were packaged, sold, and frozen in waxed butcher paper.  However, frozen meats wrapped in butcher paper are susceptible to freezer burn.  Air interacts with the surface of frozen foods, causing dehydration and/or ice crystal formation on the surface. Freezer burn is not a food safety issue, but the dark, dehydrated spots on the surface have been reported to have undesirable, oxidized, cardboard flavors. Vacuum packaging provides an air tight seal, thus reducing or eliminating freezer burn. The average consumer may purchase a side or a large quantity of pork and store it frozen for future meals. Vacuum packaging will ensure that the last piece of pork out of the freezer will taste as good as the first package.  Vacuum packaging may cost more, but the repeat sales and consumer satisfaction are often worth the extra costs for the added customer satisfaction for those selling large quantities of meat.

Labeling meat can be as simple as the total price on the package, but as the business grows into other markets, labeling can become more complex. Traditionally, labels display the name of the retail cut, the weight of the meat, and price per pound, along with the total price, and ‘expiration’ date; however, labels also may display the inspection legend, the name of the farm, and safe handling instructions. Check with your local farmer’s market and health department on the regulations for proper labeling where you plan to sell meat. Most meat processors will be willing to work with you on proper labeling and packaging.

Processed Meats

Over 70% of the pork carcass can be further processed into items such as bacon, ham, and sausage. Heritage pig breeds are ideal for processed meats. There are several artisan meat curers, throughout the country, that are using old-world European techniques to produce high quality products. These processors are looking for heritage breeds to help them further create unique, high quality cured pork products. Heritage pig farmers should make contact with these artisan meat curers and hopefully create a new revenue stream for the farm.


Heritage pigs are becoming more popular in the local food movement and are an excellent way to add value to the farm. Some breeds tend to be fatter and lighter muscled when compared to the modern, conventional market hog. Therefore, these animals are not intended for the commodity market, but should be marketed through farmer’s markets, on-farm sales and/or white table cloth restaurants or direct to chefs and curers in order to capture the full economic value. Although a farmer may only sell a small amount of meat annually, it still has to be inspected prior to sale.  Successful heritage breed farmers will cultivate a positive relationship with their meat processor. Please contact your local Extension agent for aid.

Literature Cited

Cassady, J.P., O.W. Robison, R.K. Johnson, J.W. Mabry, L.L. Christian, M.D. Tokach, R.K. Miller, and R.N. Goodwin.  2004. National Pork Producers Council Maternal Line Genetic Evaluation: A comparison of growth and carcass traits in terminal progeny. J. Anim Sci 82:3482-3485.