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Thirty-two Duroc pigs were used to investigate the relationship of potassium in the live animal and carcass to physical and chemical carcass composition. The interrelationships were determined between chemical constituents in the wholesale cuts, the composite right side and yields of lean cuts and fat. Potassium was determined by the 40K content of live pigs and unsplit carcasses and by flame photometry of samples from individual wholesale cuts. Nitrogen, sodium, fat and moisture determinations were made of samples from the individual wholesale cuts.Potassium content differed among the various wholesale cuts when calculated on a wet basis. However, when calculations were made on a fat-free or fat-free-moisture-free basis, the soft tissues of the ham and loin were the same with the shoulder, belly and jowl having lower levels of potassium. The lowest potassium levels were observed in the fat and skin. Bone was intermediate between soft tissues and fat.Significant positive relationships (P<.01) were observed between potassium content of live pigs (40K) and their carcasses (40K and flame photometry) and yields of the lean cuts, percent moisture, ash and protein of the carcass. Potassium analyses using flame photometry or 40K content of the carcass were more closely associated with carcass composition than potassium from 40K content of the live animal. Relationships between potassium content of the carcass (40K and flame photometry) and yields of lean cuts and fat were of similar magnitude as relationships between moisture, fat and protein of the carcass and yields of lean cuts and fat.

The 201 hogs included in this study consisted of 116 Landrace-Poland crosses, 76 Hampshires and 9 Durocs. Differences between breeds and crosses were not studied.Hogs slaughtered in the spring had digestive tracts of a lighter weight and a higher dressing percentage than hogs slaughtered in the autumn. The differences in the weight of the digestive tracts and digestive tract contents (fill) had a marked effect upon dressing percent.Dressing percent was significantly correlated with the yield of carcass trim and leaf fat, four lean cuts plus lean trimmings and the yield of miscellaneous cuts, i.e., feet, tail, kidneys, neck bones and jowls. Per unit yield, the yield of miscellaneous cuts contributed more to dressing percent than the yield of fat and fat more than the yield of lean; nevertheless, the yield of lean contributed more to dressing percent than either the miscellaneous cuts or fat by virtue of a greater percentage yield per carcass.Dressing percent was significantly correlated with carcass width and depth measurements. Likewise, carcass depth and width measurements were directly correlated. Carcass length was negatively correlated with measurements of carcass depth and width. Carcass length, however, was not significantly correlated with dressing percentage.The study indicates that dressing percent of hogs can be estimated from carcass measurements as well as from the component yields of cuts from the carcass. The latter appears to be the more reliable of the two methods.

Forty-eight Poland China barrows were used in an experiment designed to study the influence of subcutaneous stilbestrol and progesterone-estradiol (high and low level) implants on average daily gain and carcass composition.The hormone implants had no significant effect on gain; although stilbestrol and the high level progesterone-estradiol combination (500 mg.–10 mg.) tended to reduce growth rate.The progesterone-estradiol implants decreased average backfat probe significantly.Carcasses of the control and treated barrows were similar; however, those from barrows implanted with the high level of progesterone and estradiol showed a trend toward increased leanness.

Data from 169 hogs were used to characterize the three backfat layers by live ultrasonic and carcass measurements as well as fat and moisture determinations. The intermediate (second) fat layer increased faster and to a greater thickness than the outer (first) or inner (third) layer in carcasses with thicker total backfat. The third fat layer contained a greater (P<.01) percent of moisture and residue than the first layer, which contained a greater proportion of these two constituents than the second layer. The second fat layer contained a greater (P<.01) percent of extractable fat than the third layer, whereas the first layer was intermediate.These results indicate that the first and second backfat layers, as measured ultrasonically or on the carcass, and the third layer as measured on the carcass, are approximately equal in accounting for variation in indices of carcass merit.The thickness of the third fat layer appeared to change more postmortem than the first and second fat layer. Thickness of the third layer was significantly (P<.05) correlated with marbling scores. Marbling scores were negatively associated with l. dorsiarea and yield of lean cuts.

Rib-eye area and fat thickness were estimated on four groups of live cattle, totaling 203, from ultrasonic measurements and subsequently compared with actual measurements taken from a cross-sectional tracing of the musculature and fat in the carcass. The correlation coefficients between live estimated area and actual rib-eye area varied from 0.58 (P<.01) to 0.89 (P<.01). Mean live animal estimates of right vs. left rib-eye areas of two groups of cattle differed less than mean actual area of right vs. left. The correlation coefficients between live estimated fat thickness and actual fat thickness varied from a low of 0.11 (P>.05) to a high of 0.63 (P<.01). A low correlation existed between measurements of a group of cattle in which the spinous processes were scribed during slaughter. Significant relationships existed between the two methods of measuring fat thickness of the three groups in which the spinous processes were not scribed. A significant relationship existed between rib-eye area measured ultrasonically 5 months prior to slaughter and actual area in the carcass but not for fat thickness. The ultrasonic method is a good method for estimating rib-eye area and fat thickness in live cattle.

Two hundred thirty-five live lambs were studied over a 3-year period to determine the usefulness of an ultrasonic procedure for measuring the l. dorsimuscle area and fat thickness. The l. dorsimuscle area in 81% of the lambs was ultrasonically predicted within 0.2 sq. in. of the actual area. A progressive increase in magnitude of correlations was noted during successive years. Ultrasonic and carcass fat thickness measurements taken at the 13th rib and 6-7th lumbar vertebrae were significantly (P<.01) correlated with carcass fat trim. Width and depth of the l. dorsimuscle were both highly correlated with l. dorsimuscle area. The l. dorsimuscle area was correlated with the weight of dissected muscles from the leg and loin. There was no significant difference between area of the l. dorsimuscle from lambs sired by rams of different phenotypic scores.These results indicate that fat thickness and l. dorsiarea of live lambs can be ultra-sonically measured with acceptable accuracy.