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Pork Carcass Standards

What Are They and Why Do We Need Them?

ASTM Committee F10 on Livestock, Meat, and Poultry Evaluation Systems

by David Meisinger

As the trade group representing America’s pork producers, the National Pork Board has been very involved in issues surrounding the measurement and prediction of lean-to-fat ratios in pork production. David Meisinger of the National Pork Board describes the need for standardization in this critical area.

The pork industry has experienced a great deal of change during the past century. Market hogs were bred for lard in the first half of the century, proving to be a great resource during both world wars. However, about mid-way through the last century, consumers started looking for leaner meat with all the nutrition they were used to but with less fat and fewer calories. The pork industry responded by breeding toward leanness. However, it wasn’t until pork packing companies started measuring carcass composition in terms of lean-to-fat ratio and communicating these differences to pork producers, that we started seeing the new “ultra-lean hog.” This occurred only in the past 10 to 15 years.

What made this rapid improvement possible was instrumentation and systems that could take linear measurements of fat and lean and calculate a lean percentage with an acceptable degree of accuracy. Some of these systems are very sophisticated with neural networks that can process up to 2200 measurements within three seconds, thereby keeping up with rapid chain speeds in our modern packing plants which harvest up to 1200 hogs per hour or more.

The systems include the low-tech ruler used to measure the depth of fat at the midline split of the carcass. This measurement in combination with the weight of the carcass is fairly predictive of the lean content of the carcass. Optical probes use light diffraction to measure the depth of the fat and the depth of the lean in the loin, which is where pork chops are derived. Using these fat and muscling measurements in conjunction with the weight of the eviscerated carcass in a regression equation establishes an estimate of the lean content.

Ultrasound applications were the next technologies to arrive. A sound signal is applied to the meat sample and the bounced back signal is read. These technologies have been shown to be similar in accuracy in measuring fat and loin depth to aid in the prediction of percent lean. A more sophisticated variation of this technology is the Autofom, which uses 16 transducers arranged on a saddle to measure the carcass every 1/2 in. [12.7 mm] as it is pulled through the hardware. This system records some 2200 measurements in a matter of a second or two and analyzes the data in a very complex assessment of the variables.

The last technology to appear was the TOBEC, which stands for total body electrical conductivity instrument. This tube contains a magnetic field that actually measures the ions to calculate water content. This can be used with a high level of accuracy to predict lean composition. This is arguably the most accurate of all the systems but does not lend itself to high speed applications as is the norm in most of the large plants in this country.

Sound Technology, Yet Standards Are Needed

Essentially all hogs in the country are evaluated for lean content and for most, this information is transmitted back to the pork producer through an economic incentive program. However, when marketing their hogs, producers are presented with the dilemma of where to sell in order to garner the highest price for their production. The reason for the dilemma is that every packer uses a different set of equations to calculate percent lean. These systems are so complex that producers do not have the time or capability to establish a common link between the programs to determine where the best price could be achieved. This is because there is no standardization among the programs. Fortunately, there is an accepted standardization as to the numerical outcome of most of these measurements and calculations—percent lean of the carcass. Most of the systems except the Autofom use percent lean as the accepted endpoint of their calculations. However, essentially every packing company uses a different set of formulas to arrive at that endpoint.

The first complaint often heard when suggesting the need for standardization is that packers all have different markets and therefore, have different needs in the type of pig they want that will satisfy these various market needs. This argument is only valid for how the various lean percentages are priced, not for how the carcasses are graded. A standardized system for calculating percent lean is sorely needed and is long overdue regardless of the hardware used to measure the variables used in the calculation. There has been a lot of data collected from total separation analysis of several thousand carcasses to establish the most accurate regression equations for each different type of instrument used on several different types of genetics. The reason for the latter, the work with different genetic lines or breeds, is that some suggest that different equations are needed because of the varying ranges of fat and lean content of different breeds. The work of the National Pork Board has shown that a very accurate equation can be established to standardize these measurements for the entire population of the genetics in this country.

The result of all these different measuring systems with different regression equations is great confusion among producers as to whether they are receiving the best deal possible for the level of leanness their hogs have. It should be understood that there should be different pricing systems across the packing industry as different packers with different markets will need a wide range of raw materials to satisfy those needs. With these different pricing systems, producers could either find the packer pricing system that best fits their typical market hog or they could use genetic improvement programs to modify their production to suit their local packer’s needs. But there is no reason that producers should have to shop around for the best measuring device and formula for estimating the leanness of their market hogs. The pork industry needs standardization!

The Types of Standards Needed

The National Pork Board is the organization representing pork producers—the farmers who raise the pigs used to make pork in this country. This organization has been integrally involved in these measurement and prediction issues for several decades. Most recently, pork producers have funded a series of large-scale studies with most of the instruments in use in the world for estimating lean content. These studies all incorporated separation analysis as the gold standard of measurement of carcass lean to fat ratio. These research investigations also included most of the technologies available and in use in this country for the measurement of linear variables for the ultimate prediction of carcass composition. A plethora of data already exists to move forward with this standardization work.

Another area needing standardization will quickly surface whenever the industry begins to measure pork quality. There are already standards for color established but there are no standards for pH, which measures the acidity of fresh pork and is an indication of the texture, drip loss, and, oftentimes, the flavor of the product. As systems are developed to measure some of these quality parameters in fresh pork and to relay this information back to pork producers, it will be necessary to initiate some discussions around the standardization of these parameters as well.

The standardization of pork carcass prediction equations would help make the negotiations for the establishment of the price paid for lean carcasses much cleaner, more straightforward, and more transparent. Pork producers would have clearer signals of what the packer needs to satisfy their customers and the consumer’s desire for lean, high quality, nutritious pork. Standardization would be about more rapid improvement resulting in a more consistent product. In short, the industry needs the standardization of carcass measures. //

Copyright 2002, ASTM

David Meisinger is assistant vice president of pork quality for the National Pork Board. He has worked for the extension service, a large pharmaceutical company, a large hog packing plant, and an ultra-large hog production operation. Meisinger is subcommittee chairman of F10.40 on Predictive Accuracy.