Duroc genetics improve meat-eating quality

There aren't many of us who don't like the image of a family of Tamworths happily routing in an orchard. However, is this the reality that puts bacon in our sandwich?

Courtesy of JSR Genetics Ltd. | A comparison of joints from white hybrid (left) and Duroc (right) pigs
Courtesy of JSR Genetics Ltd. | A comparison of joints from white hybrid (left) and Duroc (right) pigs

Certain sectors of the market are becoming more discerning in their taste when it comes to pork meat. Economic issues may play a part; as the cost of animal protein increases, consumers want quality if paying a premium. British TV chefs get very excited about rare breeds and extol the virtues of the benefits in eating quality. But how much of this is about the sales story? There aren't many of us who don't like the image of a family of Tamworths happily routing in an orchard. However, is this the reality that puts bacon in our sandwich?

Marketing pressure has meant that retailers in northern Europe have included rare breed bloodlines into their premium ranges. However, meat-eating quality has often been shown to be no better than that from a commercial white line. Fine dining restaurants and even gastro-pubs also use provenance to promote their superior quality fare and perhaps justify the price. It is true that consumers want to know more about the origin and production of the goods they buy. Perceived quality as well as value is what keep customers loyal.

Why choose Duroc?

Duroc pigs were originally bred to capitalize on their productivity, with litters of fast growing, vigorous piglets. The resulting pork has superior eating quality, which is noted to be more succulent. Many producers are looking for pigs that produce premium quality meat whilst being efficient. A concern with the purebred Duroc is that the cost of production will be significantly higher than that of a commercial white line. Reproductive performance is also poorer, with smaller litter sizes seen.

Standard selection methods focusing on efficiency and leanness will reduce meat-eating quality. Therefore, positive selection strategies are essential to reverse this trend. Breeding companies are employing initiatives to improve meat quality traits using Duroc genetics.

Meat quality means science

The Japanese and other Asian markets have long prized the Duroc for its meat-eating quality. So what does the Duroc bring to the (dinner) table? The pigs have a higher level of intramuscular fat, which results in the marbling effect. The meat is also darker in color, with lower drip loss and a slightly higher pH. Duroc pigs also have greater back fat and the meat is reported to be tastier, with a lower bite resistance.

As consumer tastes become more sophisticated, their perception of meat quality changes. This movable feast therefore becomes a challenge for the producers, driving the need to extend ranges and regularly launch new products. Pork is not always eaten as a joint of meat, which complicates the assessment of meat quality for different breeds. It is often the subject of further processing: bacon, sausages, hams, etc.

In taste tests, Duroc pork was found juicier and tenderer than white breeds. This was attributed to the marbling and possibly the higher concentration of red oxidative muscle fibers, which contain more lipids. Water holding capacity, intra-muscular fat, tenderness, meat color and pH are all linked, heritable factors. These account for approximately 30 percent of the variation in most pork meat quality traits.

As the proportion of Duroc genes increases, lean carcass content decrease and back-fat levels increase. Studies have compared meat from pigs with 0, 25 and 50 percent Duroc genes. Pigs with only 25 percent Duroc genes produced pork with no greater acceptability than white breeds. Research and subsequent practice has clearly demonstrated that at least 50 percent Duroc genes are required in the slaughter generation to obtain the superior meat-eating quality.

The Duroc as a terminal sire

Purebred Duroc boars are used as a terminal sire commonly crossed with white hybrids. As already discussed there is a dilemma as to how much Duroc to include in a breeding program. It is for this reason that geneticists have been working on keeping the meat-eating quality of the Duroc, whilst improving its performance. In recent years they have focused on increasing efficiency and reproductive traits of their Duroc purebred lines. They have selected for improved feed conversion and reduced back fat thickness. It is for this reason that Duroc sires are now being rated highly for feed efficiency. Caution is required, however; research has shown that intensive selection for feed conversion in purebred lines can actually result in poorer meat quality.

Duroc genetics are used in many commercial lines, provided by different breeding companies. These have been developed for a variety of purposes and markets. Efficient Duroc lines are bred for the main pork producing countries wanting quality meat. For producers looking for meat with enhanced marbling, which can be sold at a premium, a specific purebred Duroc line is used as a terminal sire. Many Asian producers exploit this strategy, as well as those in other countries supplying these markets; for example, Canada.

Red versus white Durocs

Purebred Duroc animals may be called red Durocs, referring to their dark red coat. Red Durocs are still kept commercially as well as for showing purposes. They are still popular in the U.S. and other countries supplying meat for niche markets. Producers may keep a Duroc boar for natural service and genetics companies will keep purebred herds for use in their genetic programs.

White Durocs are often referred to, but this is a misnomer as all purebred Durocs are red. A white Duroc is a pig that has already been crossed with a white breed. Most commonly this is a Large White or Landrace. These crosses may be used as terminal sires and female lines in their own right, or to create a hybrid. Hybrids including Duroc are available from major genetic brands, in both North America and Europe. The percentage of Duroc included varies, and as well as Large White and Landrace, other breeds such as the Pietrain, may be included.

Duroc for extensive production

Meat quality is not the only reason that Duroc lines are included in genetic breeding programs. The breed is ideal for high-welfare and semi-intensive systems. Female Duroc lines are often included in pigs bred for outdoor production. The breed's robustness and mothering ability makes them well-suited to environmental challenges. In order to maximize hybrid vigor in the parent sow, one company uses a sow that is 50 percent Duroc. This means that the slaughter generation are 25 percent Duroc, not enough to see the benefits in meat-eating quality, but enough to produce hardy piglets.

Duroc pigs are often kept by Spanish producers and crossed with the traditional Iberian pig, which is used to produce dry-cured hams. Again, the increase in intra-muscular fat is of benefit to this specialist product. Not only does it assist in the curing process, but it also improves the sensory characteristics of the resulting ham. Using a Duroc/Iberian cross also improves the efficiency of production.

Consistency over novelty

In the case of Duroc, both quantity and quality are key. Fifty percent of Duroc genetics is required in the slaughter generation to see significant improvements in meat-eating quality. Some compromise in efficiency is inevitable, so the feasibility of using this strategy is dependent on the market. If the pork is sold into the Asian market, then no doubt Duroc lines will be essential. However, other premium markets in the U.S. and Europe are developing. In the UK, for example, Duroc hybrid producers have supply chain agreements for premium supermarket products and pork for high-end restaurants.

As we know, conventional selection for leaner, efficient sires will lead to diminishing meat-eating quality. However, there is market demand for premium pork products. Rare-breed pork has its place in niche markets, but its novelty value may not last. The cost and inconsistency of using rare breeds will not always make economic sense.

If the need for meat quality is to be met in a sustainable and efficient manner, then a science-based solution is required. Utilizing Duroc genetics makes sense as a consistent and commercially viable way of producing premium pork.

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