The composition of the average market hog has changed significantly in the last decade — tipping the scales at heavier weights and with considerably less backfat.

That is the summary of the American Meat Science Association's “Benchmarking Value in the Pork Supply Chain” final report released recently.

The benchmarking project, supported by pork checkoff, several packers and genetic companies, surveyed pork processing companies to identify, quantify and rank factors influencing pork quality, explains Floyd McKeith, lead researcher from the University of Illinois. The survey and resultant report drew on the original Pork Chain Quality Audit Survey from 1993, which identified and quantified several pork quality issues, he notes.

In that early work, producers, packers and processors zeroed in on key issues causing economic losses. They included: excessive fat, inadequate muscle color/water-holding capacity, inconsistent live weights, excessive abscesses and bruising. The 2003 survey provided a follow-up to those pork quality issues.

Meat processors provided slaughter data on 64% of the 98 million federally inspected barrows and gilts slaughtered in 2002. The survey featured three phases. The first surveyed packers; the second studied products manufactured from various fresh pork cuts; and the third looked at the consumer acceptability of different products at varied pricing levels. All major hog-producing areas in the U.S. were represented.

From the quality perspective, the survey reveals two definitions of pork quality currently in use. “One pertains to the technical aspects of pork quality and is defined by purge loss, water-holding capacity, objective color, percent fat and percent lean,” McKeith explains. The other reflects the consumer's expectation of quality, which focuses on subjective color, tenderness, juiciness, flavor and nutrition, he adds.

Notable Carcass Trait Changes

Compositionally, the 1993 concern about excessive fat was addressed handily. Backfat was reduced 36% during the decade that followed, trimming average backfat thickness from 1.07 in. to 0.69 in.

Looking closer at the distribution of backfat depths, Table 1 verifies that nearly 96% of the hogs represented in the survey had less than 0.98 in. of backfat. “This significant improvement can be credited with improved genetics, feeding techniques, marketing plans, housing and an understanding of environmental influences and their impacts,” McKeith says.

The carcass trait, backfat and live weight data in Table 2 reinforces that, as backfat decreases, overall weight and muscle increases. This change in composition is also reflected in Table 3. The average U.S. market hog now has 55.5% lean muscle, up from the 49.5% recorded in the '93 audit. In 2003, nearly two-thirds of market hogs landed in the 54-56.9% muscle slot. Of course, that leaves over a third of U.S. market hog carcasses with less than 53.9% muscle.

Even as backfat was being trimmed, live weights increased by 10 lb. during the decade — from a 245-lb. average to just over 255 lb. Nearly 45% of the market hogs fell within the middleweight category (242-269 lb.). The next largest category, 271-300 lb., accounted for just over 34% of market hogs; 14.1% landed in the 200-240-lb. range. At the extremes, 5.9% weighed over 300 lb., 1.1% less than 200 lb.

“This trend reflects the increase in slaughter weights currently in practice today,” McKeith observes. “Increases in average daily gain, feed efficiency and improved nutrition can also be attributed to the processing weight increase.”

Table 1. National Pork Benchmarking Audit Estimate of Backfat Thickness of U.S. Market Hogs
Backfat thickness range, in. Carcasses with backfat thickness in this range, % Minimum Maximum
Below .59 12.3 0.0 15.0
.59 - .78 55.3 2.0 53.0
.78 - .98 28.1 5.0 29.0
.98 - 1.18 3.5 2.0 42.0
1.18 - 1.38 0.7 0.0 42.0
1.38 - 1.58 0.1 0.0 25.0
1.58 - 1.78 0.0 0.0 25.0
Over 1.78 0.0 0.0 6.0


Table 2. National Pork Benchmarking Audit Estimate of Carcass Traits of U.S. Market Hogs1
Average
Trait 1993 2003
Live weight, lb. 245.1 255.7
Backfat thickness, in. 1.07 0.69
Carcass muscle, % 49.5 55.5
Ham weight, lb. 21.8 26.0
Loin weight, lb. 17.2 20.9
Boston butt weight, lb. 6.2 6.0
Belly weight, lb. 14.8 15.0
1Estimates of variability are the ranges of the specific traits and the frequency of hogs falling into those ranges which are included in the tables.


Logically, the heavier live weights yielded heavier carcasses, which, of course, translated to heavier wholesale cuts. A comparison to the '93 data verified this trend. Interestingly, hams and loins averaged 3-4 lb. heavier in 2003 compared to 1993, while Boston butt and belly weights were relatively unchanged.

The distribution of ham, loin, Boston butt and belly wholesale cut weights is shown in Table 4. Average weights for each of the wholesale cuts were: ham, 26 lb.; loin, 20.9 lb.; Boston butt, 6 lb.; and belly, 15 lb.

From a meat quality perspective, the audit reported an increase in PSE (pale, soft, exudative) pork. In 1993, 10.2% of the pork was PSE, compared to 15.5% in 2003. Reinforcing the trend, pork exhibiting normal quality characteristics — color/firmness and structure — dropped from 86% in 1993, to 82.6% in the current report. The amount of DFD (dark, firm, dry) pork was cut in half, from 3.8% to 1.9% in 2003.

Table 3. National Pork Benchmarking Audit Estimate of Percentage of Muscle in Carcasses of U.S. Market Hogs
% Muscle range Carcasses with muscle percentages in this range, % Minimum Maximum
Below 45 0.7 0.0 3.0
45 - 47.9 2.0 0.0 6.0
48 - 50.9 8.1 0.0 20.0
51 - 53.9 25.9 11.0 79.0
54 - 56.9 63.0 12.1 88.0
57 and over 0.3 1.0 1.0


“This suggests that as the composition of the market hog has become leaner, management of the leaner animals must be altered to ensure normal pork characteristics,” McKeith says. Packers and purveyors indicated that weather (season) had the largest impact on the occurrence of PSE in carcasses and wholesale cuts.

Table 4. National Pork Benchmarking Audit Estimate of Weights of Wholesale Cuts from Carcasses of U.S. Market Hogs
Weight range, lb. Percentage of carcasses with wholesale cuts in this weight range Minimum Maximum
Ham
Below 14.0 0.0 0.0 0.0
14.0 - 17.0 0.6 0.0 5.0
17.0 - 21.8 7.8 3.0 35.0
21.8 - 25.0 25.4 15.0 49.0
25.1 - 27.0 5.8 13.0 66.0
Above 27.0 20.4 0.0 32.0
Loin
Below 19.0 26.0 5.0 60.0
19.0 - 23.0 53.5 26.0 80.0
Above 23.0 20.5 0.0 50.0
Boston Butt
Below 4.0 1.2 0.0 9.0
4.0 - 8.0 59.0 30.0 100.0
Above 8.0 39.8 0.0 65.0
Belly
Below 10.0 2.8 0.0 15.0
10.0 - 12.0 7.2 2.0 53.0
12.0 - 14.0 14.1 5.0 29.0
14.0 - 16.0 26.7 2.0 42.0
16.0 - 18.0 25.5 0.0 42.0
18.0 - 20.0 14.5 0.0 25.0
20.0 - 25.0 7.8 0.0 25.0
Above 25.0 1.4 0.0 6.0


Carcass Condemnations

Whole or partial condemnations represented 0.4% and 2%, respectively. In other words, 340,000 whole carcasses were condemned, while 1.95 million carcasses were assessed partial condemnation. “The partial condemnations does not include all trimming conducted on the carcass,” McKeith explains. “Rather, it represents times when substantial sections are removed from the carcass.”

The total condemnations, whole or partial, represented approximately 2.3 million animals. Animals or carcasses reported condemned for disease represented 52% of the total. Diseases such as erysipelas, metritis and septicemia were represented, but not all inclusively. The “diseased” segment accounted for the equivalent of approximately one million market hogs or 1% of the total annual slaughter.

Abscesses were the next largest source of condemnation at 9.3%, which was down from 11.1% in the '93 survey.

Arthritis, bruising and skin problems were responsible for about 19% of condemnations (7.5%, 6.5% and 5.1%, respectively).

Carcass Loss Summary

The dollar value loss for carcass nonconformities reported in the 2003 audit averaged $8.08/carcass. That compares to $9.88/carcass in 1993's audit.

The largest losses, $1.32, were attributed to inconsistent weights — which encompassed live, carcass and wholesale cut weights. Thin bellies ranked next for economic losses, averaging $1/carcass. PSE was the third most prevalent problem, costing 90¢/carcass, because of increased purge losses in fresh pork and decreased protein functionality in processed products. And, even though market hog composition had changed considerably, an 85¢ penalty was waged against the average carcass for being too fat. Most of this excess appeared in the shoulder and ham. And, it is noteworthy that an average 57¢ was lost per carcass because of abscesses/injection sites.

Copies of the complete “Benchmarking Value in the Pork Supply Chain” report are available for $75/copy from the American Meat Science Association. Call (217)356-5368 or e-mail: information@meatscience.org.