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Thirty Yorkshire and seventy Hampshire barrows were slaughtered at five pre-determined weights (45.4, 68.2, 90.0, 113.6 and 136.4 kg) in an effort to characterize changes in composition with respect to muscle, fat and bone in heavily-muscled pigs. Standard carcass measurements were obtained and the right carcass half of each pig was separated into lean, fat and bone.The relationship between average backfat thickness and weight appeared to be linear in the Hampshire data, while a non-linear (P<.05) relationship was found in the Yorkshire data. Rather uniform increases in loin eye area and carcass length were observed from 68.2 to 136.4 kg in the Yorkshire data, while non-linear (P<.05) responses, more characteristic of the “Classical” growth curves for loin eye area and length, were found in the Hampshires.Linearlike trends were observed between kilogram of lean, fat and bone with slaughter weight in the Yorkshire data. The stage of greatest increase in lean composition occurred from 90.9 to 113.6 kg for both breeds. The relationships between kg of lean cuts, ham and loin, and ham with slaughter weight appeared to be linear in the Yorkshire data; however, non-linear (P<.05) responses for lean cuts and ham and loin were found in the Hampshires. A slight decrease in lean cuts, when expressed as a percentage of carcass weight, was found with increased weight for each breed; however, similar trends were not observed for ham and ham and loin yields.

Thirty Yorkshire and seventy Hampshire barrows were slaughtered (n = 20 at each weight) at live weights of 45.4, 68.2, 90.9, 113.6 and 136.4 kg and evaluated for carcass merit using two different techniques; potassium-40 and Duncan Lean Meter live backfat probe. Each pig was taken off feed and 40K counted at each weight. Upon reaching the predetermined slaughter weight, each pig was probed using the Duncan Lean Meter, 40>K counted for the final time, and then slaughtered for carcass evaluation. Standard carcass measurements were obtained, the right half of each carcass was separated into lean, fat and bone and lipid-free lean was determined by ether extraction of the lean.As slaughter weight increased up to 113.6 kg the 40K counted at each weight, each pig was probed using the Duncan Lean Meter, count of the Yorkshires appeared to increase in a linear fashion; however, a non-linear (P<.01) response was found in the Hampshire data across five slaughter weight groups.Simple regression studies across slaughter weights indicated that weight alone accounted for 96.1% of the variance when predicting lipid-free lean in Yorkshires and 93.6% of the variance in the Hampshires. Potassium-40, when used alone in a regression equation, accounted for 91.3 and 85.7% of the variation, while live backfat probe was associated with 73.1 and 76.2% of the variation when predicting lipid-free lean in the Yorkshires and Hampshires, respectively. Multiple regression equations involving live weight, 40K count, and Duncan Lean Meter live backfat probe were developed to estimate kilograms of lipid-free lean and accounted for 98.2 and 96.3% of the variation in this trait with standard errors of estimate of 1.78 and 2.04 kg for Yorkshires and Hampshires, respectively.

A random sample of pork carcasses (n = 120) was evaluated at a commercial slaughter facility. Backfat and carcass length measurements were obtained immediately after slaughter; color, firmness, marbling, loin eye area and ultimate pH were evaluated 48 h postmortem. Chops were evaluated by a six-member, experienced sensory panel. Results for carcass and palatability traits indicate that substantial variation exists for most characteristics. Average backfat (mean = 3.56 cm) ranged from 2.03 to 5.76 cm, and loin eye area (mean = 29.96 cm2) ranged from 21.42 to 44.52 cm2. Sensory panel tenderness values (mean = 9.4) varied substantially, with 22% < 7.5; correspondingly, Warner-Bratzler shear (WBS) values ranged from 2.01 to 6.96 kg, and 16.7% were > 4.5 kg. Juiciness scores (mean = 8.4) were also quite variable; 27.5% of the values were <7.5. Sarcomere length, collagen content and percentage of soluble collagen were not related to tenderness or WBS values; a significant but low correlation was observed between percentage of soluble collagen and connective tissue amount (r = .19; P<.05). Of the parameters evaluated, percentage of im fat was most highly related to tenderness and WBS force (r = .32 and −.29, respectively). Results of this study indicate that there is currently substantial variation in carcass and palatability traits of pork entering the marketplace.