Lean Cuts Research Articles

Chapter I: Background, Objectives, and Design

Extensive evidence implicates diet as one of the key factors in the etiology of atherosclerosis, and suggests that the disease can be prevented by changes in diet, particularly to lower serum cholesterol level. In 1960, an Executive Committee on Diet and Heart Disease was established to explore the matter of mass field trials on the prevention of atherosclerotic coronary heart disease. After two years of deliberations, the Executive Committee concluded that a well controlled mass field trial was needed to test the hypothesis that alteration of the amount and type of fat and the amount of cholesterol in the diet would decrease incidence of first attacks of clinical coronary heart disease in middle-aged American men. It estimated that a study population of up to 100,000 men, with a follow-up period of four or five years, would be required to obtain a statistically reliable test of the hypothesis if the incidence were reduced by 20 per cent. The Committee further concluded that, on the basis of information then available to it, a definitive decision could not be made concerning the feasibility of such a large-scale study. It therefore recommended that the next major endeavor be a smaller feasibility study. Based on this recommendation, a common protocol was developed for a collaborative feasibility study. Feasibility of two types of mass field trial was to be evaluated: 1. among free-living men from the general population, and 2. among long-term residents of mental institutions, with both studies to be conducted on a double-blind basis, through use of special fat-modified foods. The original protocol enumerated eleven topics to be clarified by this National Diet-Heart Study in a one to two year research endeavor: 1. Effectiveness of recruitment of volunteers from several sources; 2. rate of volunteering; 3. effectiveness of three concomitant dietary modifications-moderate reduction of per cent calories derived from total fat and/or saturated fat, increase in per cent calories from polyunsaturated fat and in the polyunsaturated to saturated fat ratio (P/S), and moderate reduction in dietary cholesterol; 4. availability, palatability, distribution, and cost of specially prepared foods; 5. indices of adherence to diet; 6. extent of reduction of serum cholesterol levels; 7. dropout, non-adherence, and non-response rates; 8. feasibility of a double-blind technique; 9. personnel, equipment, and physical facilities necessary; 10. geographic and laboratory variations within a common protocol; 11. experience in the pooling data from a cooperative study. Findings of the first months of the Study revealed several problems requiring further investigation. Therefore, the decision was made to continue beyond the first year, with appropriate modification of the protocol for the second year. These further efforts-designated the Extended Study and the Second Study respectively-aimed to evaluate the following major problems, in addition to those explored during the initial year (First Study): 1. What proportion of the participants in the First Study would volunteer for the Extended Study? What would the non-adherence and dropout rates be in the Extended Study and the Second Study (with use of newly recruited men in the latter)? 2. Could new individuals be recruited for such studies with the explicit understanding that some of them would be randomly assigned to a control group? 3. Could costs be reduced by having participants select lean cuts of meat on the open market? 4. Could participants be satisfactorily instructed to select and trim meats? Would their intake of fat and cholesterol be well controlled? Would they demonstrate adequate blood lipid responses? 5. Could new experimental diets, acceptable to the participants, be devised and evaluated? How would they compare to the diets utilized in the First Study? Could the differences between control and experimental groups be enhanced? 6. Could diet modification programs be made less demanding for participants, nutritionists, and investigators? Would such altered programs be effective? 7. Could any evidence of a seasonal variation in serum cholesterol level be detected, as a possible confounding factor influencing the trend of serum cholesterol level? Facilities for the study of free-living or "open" populations were established in five cities (Baltimore, Boston, Chicago, Minneapolis-St. Paul, Oakland), and of an institional or "closed" population at the Faribault State School and Hospital, Minnesota. A Central Staff was established, and-in co-operation with the Principal Investigators-it procured and distributed the special fat-modified foods; developed forms and a manual of uniform procedures; distributed these materials; administered the double-blind design; maintained quality control; and assumed responsibility for the central collection, tabulation, analysis, and distribution of data. A Central Laboratory analyzed all sera for total cholesterol.

Variation in porcine muscle quality of Duroc and Hampshire barrows.

Various carcass and production characteristics of 123 Duroc and 155 Hampshire barrows of known breeding were compared. Loins and hams of Duroc barrows were significantly firmer and darker in color (P<.01) and the loins contained more marbling (P<.01) than loins and hams from the Hampshire barrows. The l. dorsi, gluteus medius and gluteus accessorius muscles of the Durocs had higher (P<.01) average pH values than the Hampshires. There was some indication within each breed that firmer loins and hams and higher muscle pH values were associated with carcasses that had lower yields of the four lean cuts. Hams and loins of both breeds were firmer (P<.01) and darker in color from carcasses that contained more marbling in the l. dorsi muscle. Firmness and color of loins were not related to rate of gain for either breed. Feed efficiency was positively (P<.01) associated with firmer and darker loins of the Durocs, but a low negative relationship was observed between these same factors for the Hampshires. Firmer and darker color loin chops from the Hampshires were less tender, while the softer and lighter color chops from the Durocs were less tender.

Influence of Season, Sex and Dietary Energy Concentration on Performance and Carcass Characteristics of Swine

Eighty weanling Duroc pigs were individually fed to study effects of season (summer and winter), sex (barrow and gilt) and dietary energy concentration (25% corn cobs; 8% corn cobs; basal; 4% tallow; and 8% tallow) on performance and carcass traits of growing-finishing swine. In winter, pigs consumed more feed per day, required more feed per unit of gain, and yielded carcasses that were fatter than in summer. However, the rankings of the relative performance of the pigs by diets were alike for both seasons. Barrows consumed more feed per day and required more feed per unit of gain than gilts, but gilts yielded carcasses that were longer, with a larger loin-eye area, a higher yield of lean cuts than barrows, and there was no sex x dietary treatment interaction. Feed required per unit of gain decreased with each advance in energy concentration, and average daily gain of pigs fed 25% cobs was 11% less than average daily gain of pigs fed 8% cobs which in turn was 11% less than gains of pigs fed the other three diets. Backfat of pigs fed the 25% cobs diet was less than backfat of pigs fed the 8% cobs and basal diets which yielded less backfat than pigs fed tallow diets. Pigs fed 25% cobs had a lower dressing percent and larger loin-eye area than pigs fed tallow.

Ultrasonic Prediction of Lean Cut Percent in Swine

Ultrasonic Prediction of Lean Cut Percent in Swine

Effects of Limited Feeding on Market Hogs: Performance and Quantitative and Qualitative Carcass Characteristics

During the winter of 1963–64, 136 pigs were randomly allotted to two replications consisting of eight levels of feeding (full feed, 2.27 kg. once per day, 2.04 kg. once per day, 1.81 kg. once per day, 1.13 kg. twice per day, 1.02 kg. twice per day, 0.91 kg. twice per day, and 1.81 kg. once per day until reaching 72 kg. bodyweight, then full feed) to study their effects on the performance and quantitative and qualitative carcass characteristics of market hogs. At 90 kg. bodyweight, the pigs were slaughtered and information obtained, with data being analyzed by the analysis of variance. Swine fed a limited amount of feed, once per day, were less efficient in utilizing the feed than pigs fed twice per day. Restricting the feed intake of swine decreased average daily gain and dressing percent; tended to decrease backfat thickness and to increase loin eye area; but had no effect on U.S.D.A. grade, ham fat thickness, specific gravity, ham-loin index on a liveweight basis, or ham-loin index on a carcass weight basis. Limiting the feed of pigs significantly decreased the percent fat trim on both the live and carcass weight basis, but did not significantly affect percent lean cuts or percent primal cuts on either basis. Restricted feeding also tended to increase occurrence of pale, soft, exudative pork and percent cooking loss of loin roasts, but did not affect the marbling, percent moisture, percent ether extract, and pH of the l. dorsior the shear force and palatability values of cooked roasts.

RELATIVE MERIT OF SIB VERSUS OWN PERFORMANCE IN SELECTION FOR LEAN MEAT PRODUCTION IN SWINE

The relative selection efficiency (RSE) of direct selection for a trait of basic interest and indirect selection on an alternate trait was examined with consideration given to several population sizes, selection intensities and genetic parameters. Slaughter of litter samples resulting in a reduction of the population available for selection was associated with the direct but not the indirect selection procedure. Values of RSE increased with increasing values of the genetic correlation, but for any given value of the genetic correlation, RSE was inversely related to the heritability of the basic trait. Population size was important only for herds comprising fewer than 10 breeding females.Using predicted percent yield of lean cuts, (A), as the trait for direct selection with [Formula: see text] of 0.2, 0.3 and 0.4 and the live back fat probe, (B), as the trait for indirect selection, with [Formula: see text] and assuming a genetic correlaton between A and B of 0.6, it was demonstrated that, respectively 38, 19 and 9% faster genetic gains in the basic trait accrued from indirect as compared with direct selection. It is suggested that the inherent reduction in population size, coupled with other practical aspects associated with carcass testing, might make the indirect selection method preferable even when RSE is less than unity.

Factors associated with differences in carcass conformation in lamb

Abstract Factors associated with differences in carcass conformation were studied in three experiments involving 85 pairs of lambs, half of which had been selected as having blocky conformation and half leggy conformation. Pairs of carcasses were matched for carcass weight and age at slaughter. The blocky carcasses contained more fat and less red meat and bone than the leggy carcasses. They also had a higher proportion of the fatter cuts (loin, ribs, and flap) and a lower proportion of the leaner cuts such as the leg. A taste panel found the palatability characteristics of leg meat from both types of carcasses acceptable and did not differentiate between them. The differences in conformation strongly influenced the export grading of the carcasses, the blocky carcasses grading predominantly Prime Down Cross and the leggy carcasses mainly Prime Crossbred and Y. Southdown sires produced the blockiest carcasses and the other breeds studied produced the leggiest carcasses. Within-breed variation was also noted...

The association between commercial cut-out yield and gross chemical composition in market pigs

In a study of 100 pig carcasses, representing a sample of the pigs used in previously reported work, gross chemical composition of the ham, shoulder, loin, belly and half carcass were determined for one side. Percentage yield (trimmed v. untrimmed) of picnic, butt, ham and loin (PBHL), and certain carcass measurements were recorded on the other side of the carcass. From the covariance analyses, it was concluded that backfat thickness of the carcass alone was of only moderate predictive value for total chemical carcass fat.Carcass protein could, for most purposes, be predicted with satisfactory precision from the percentages of protein in the loin or in the ham, with residual standard deviations of 0·27 and 0·36% respectively.Although percentage yield of lean cuts may be considered satisfactory for commercial evaluation of swine carcasses, it was not an accurate index of the true leanness of a carcass expressed as the percentage of chemically determined protein.Multiple regression equations were computed for predicting the percentage of protein in the carcass and percentage yield of PBHL from conventional carcass measurements. The residual standard deviations for predicting the percentage of protein were 0·49 for the males and 0·42 for the females; for percentage yield of PBHL these were 1·31 and 1·22 respectively. Total backfat thickness was the most important single variable in predictions. Variances among sexes were non-homogeneous for the important traits, with the females in all cases showing the greater variability. The results of regression analysis within sex indicated that, for maximum precision, a separate prediction equation for each sex was required.

Study of Backfat Layers of Swine

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. dorsi area and yield of lean cuts.

RADIOGRAPHY OF THE LIVE ANIMAL AS A TECHNIQUE FOR PREDICTING CARCASS CHARACTERISTICS IN SWINE

Radiographs obtained on 3460 Lacombe and Yorkshire baby pigs were examined to determine the association between vertebral size and number and carcass length. Carcass length increased approximately 1.3 cm per unit increase in vertebral number. Consideration of birth weight, slaughter weight, age at slaughter, and linear measurements of vertebrae at birth were not of value in improving the precision of prediction.A subgroup comprising 615 Lacombe pigs at slaughter weight were X-rayed immediately prior to slaughter in order to assess the predictive value of X-ray measurements of the vertebrae and backfat at slaughter weight. Multiple regression utilizing vertebral number and vertebral length at slaughter explained some 34% of the variation in carcass length. X-ray measurements of backfat thickness on the live animal were not found to be superior to the live probe in predicting percentage yield of lean cuts, and it was concluded that the radiographic technique was not superior to the simpler probe method for predicting cutout yield from measurements made on the live animal.

Relationships among some Physical and Chemical Parameters of Full- Versus Limited-Fed Yorkshire Pigs Slaughtered at Different Live Weights

An experiment was designed using 30 Yorkshire pigs to study the influence of slaughter weight and feed restriction on carcass cut-out data and to relate these physical measurements to the chemically‐determined proximate components. As slaughter weight increased from 79 to 102 kg., the percent of all lean cuts decreased significantly, while that of fat cuts and back-fat thickness increased significantly. Absolute amounts of both fat and lean cuts increased with slaughter weight. Feed restriction significantly increased most of the lean parameters studied and reduced the fat measurements. It increased percent of head and reduced the percent of offal (gastrointestinal tract minus contents, head, respiratory tract and all other internal organs). Correlations between leaf fat and empty body weight and between leaf fat and carcass extractable fat were higher than between back fat and the same parameters. Therefore, leaf fat may be a more satisfactory index of true body fat than is back fat, although the best index still is the carcass extractable fat, for which the correlation with the empty body fat was 0.99. The offal proximate chemical components were highly correlated with those of the carcass and the empty body. A knowledge of the chemical composition of the offal alone is, therefore, a good reflection of the chemical composition of the empty body. Percent of extractable fat in the empty body, carcass, or offal were positively correlated with fat measures and negatively correlated with all lean measures and with the protein and water. Percents of water and protein were positively correlated with the lean parameters and negatively correlated with all fat characteristics. The saturated fatty acids were positively related to all fat measures and to average daily gain and gross energy of the body and negatively correlated with all lean measures and water and protein. The reverse was true for the unsaturated fatty acids. Also, some strong inverse relationships were found between some unsaturated and saturated fatty acids. The chilled dressing percent was poorly correlated with nearly all physical and chemical measures and, therefore, should not be regarded as a satisfactory index of physical or chemical parameters. Copyright © 1966 American Society of Animal Science. Used by permission. R E L A T I O N S H I P S A M O N G S O M E P H Y S I C A L A N D C H E M I C A L P A R A M E T E R S O F F U L L V E R S U S L I M I T E D F E D Y O R K S H I R E P I G S S L A U G H T E R E D A T D I F F E R E N T L I V E W E I G H T S G. M. ]~ABATUNDE, W. G. POI~D, L. D. V A N V L E C K , G. H. K R O E N I N G , 1 J. T. REID, J . R . S T O U F F E R AND G. H. W E L L I N G T O N 2 Cornell University, '~ Ithaca, New York I T is well established that feed restriction, when imposed at the right stage of growth of the pig, tends to increase the proportion of lean cuts in relation to fat. Most reports have dealt primarily with physical factors such as growth rate, feed efficiency, back-fat thickness, loin-eye area, percent lean cuts and carcass length. Only a few reports (McMeekan and Hammond, 1939; McMeekan, 1940; Zobrisky et al., 1958) have included a more detailed analysis. Similarly, only a few reports (Lu et al., 1958; Zobrisky et al., 1954, 1958; Gnaedinger et al., 1963; Doornenbal, 1961) have described relationships between physical and chemical measurements of the pig. The purposes of this investigation were to study (1) influences of slaughter weight and feed restriction on physical characteristics of the pig carcass and (2) relationships between physical carcass measures and chemical components of the body.

Influence of percent oats in the diet, lysine and methionine supplementation and of pelleting on rate and efficiency of gain of growing pigs, and on carcass characteristics.

Two hundred forty growing pigs were used in two experiments to evaluate the effects of replacing 0, 10, 20, 30 and 40% of the corn in typical corn-soybean meal diets with oats, of lysine and methionine supplementation and of pelleting on rate and efficiency of gain. One hundred ninety-six pigs were slaughtered to determine the effects of treatments on carcass characteristics. In one experiment rate of gain was decreased significantly due to the use of 40% oats in the diet, but oat level was without significant effect in the second study. Efficiency of feed utilization decreased in both experiments with increasing oat content of the diet. Supplementation of the diets with 0.15% L-lysine and 0.10% DL-methionine, alone and in combination, did not affect rate and efficiency of gain. Pelleting of the diets in the second experiment did not influence rate of gain, but did result in a significant decrease in feed required per unit of gain. Carcass leanness as measured by backfat thickness, cross-sectional area of the longissimus dorsi muscle, and percent four trimmed lean cuts or percent trimmed ham and loin of slaughter weight was not improved by any of the dietary treatments, nor was it affected adversely by pelleting. Dressing percent decreased with increasing oat content of the diets. Gilts had significantly larger cross-sectional area of the longissimus dorsi muscle and greater yields of the four trimmed lean cuts and of trimmed ham and loin than barrows.

PREDICTION OF YIELD AND VALUE OF HOG CARCASSES

Relationships between a number of split and internal carcass measurements and per cent yield of the carcass and its component cuts when trimmed in accordance with commercial standards were examined using a sample of 482 hog carcasses. Carcass length and weight were found to have low predictive value, accounting respectively for approximately 9 and 4% of the total variance in per cent yield of the trimmed lean cuts (ham, loin, picnic, and butt). Commercial grade explained approximately 27% of the variance in this trait and sex approximately 21%. The most useful predictors of per cent yield of lean cuts, and the proportion of total variance explained by each, were: per cent yield of trimmed loin, 83%; ratio of loin area to total back fat, 53%; total back fat, 54%; and per cent lean in the ham face, 43%. A regression equation combining total back fat, loin area, and per cent lean in the ham face explained 63%. Regression equations are provided and implications as regards commercial grading and carcass appraisal for progeny testing are discussed.

Influence of Diethylstilbestrol Implantation on Growth and Carcass Characteristics of Boars

In seven trials the effectiveness of implanting boars with diethylstilbestrol (DES) was studied as a method for overcoming or delaying the development of the odor or flavor commonly associated with boar meat and for retaining or further improving the desirable performance and muscling characteristics of the boar. Feedlot performance as well as carcass and organoleptic characteristics of marketweight (205–215 lb.) barrows, boars and boars implanted with either 48 mg. DES at 155 lb. liveweight or 96 mg. at 145, 155 or 165 lb. were compared. The rate of gain of boars implanted with 96 mg. of DES at a liveweight of 155 lb. was significantly faster than that of unimplanted controls and barrows, and treatment also resulted in an improvement in efficiency of feed conversion. Barrows were significantly shorter and fatter than control boars, or boars implanted at 155 lb. with either 48 or 96 mg. DES. This difference was reflected in a significant decrease in the yield of lean cuts in barrows as a percent of carcass weight. Implantation of boars at a liveweight of 155 or 165 lb. did not significantly alter the desirable lean muscling characteristics of the boar carcass, although implantation of 145 lb. with 96 mg. DES did increase fat deposition and decrease the lean cut yield. Area of longissimus dorsi muscle was not influenced by implantation of 96 mg. DES at 155 lb., while the deposition of intramuscular fat in this muscle was significantly increased and color of the muscle was more uniform. Sex odor and flavor in 1Oth-rib loin chops were significantly reduced and in no case were the carcasses from boars implanted with this level of DES condemned because of odor or flavor score. There was a non-significant residue of DES in the loin tissue from implanted boars.

Amino Acid Supplementation, Effect of Added Lysine in Swine Diets on Lean Cuts and Enzyme Activity in the Heart and Liver

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAmino Acid Supplementation, Effect of Added Lysine in Swine Diets on Lean Cuts and Enzyme Activity in the Heart and LiverR. L. Shirley, H. D. Wallace, G. E. Combs, A. Z. Palmer, and G. K. DavisCite this: J. Agric. Food Chem. 1963, 11, 6, 530–531Publication Date (Print):November 1, 1963Publication History Published online1 May 2002Published inissue 1 November 1963https://doi.org/10.1021/jf60130a027RIGHTS & PERMISSIONSArticle Views28Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (240 KB) Get e-Alerts Get e-Alerts

Subjective Evaluations of Cutting Yields and Rib-Eye Area in Live Hogs and Carcasses

Studies of the ability of panels of judges to differentiate between live hogs and their carcasses for economically important characteristics have been made using a paired comparison technique. Judges of live hogs tended to be more consistent in their judgements than did those of carcasses and to achieve a perfect ranking of the seven hogs comprising each batch more nearly, although the carcass judges showed a marked improvement as the experiment progressed. Both panels of judges found it more difficult to make consistent judgements of the percent yield of untrimmed loin than of rib-eye area or of the yield of trimmed lean cuts. Rankings of live hogs for the yield of untrimmed loin showed very little relation to the actual yield of this cut, and only a slight relation for the carcass judges. Rankings of live hogs and carcasses for rib-eye area and the yield of trimmed lean cuts were both significantly related to these characteristics although, in the case of lean cut yield, the judges' predictions were no better than could have been achieved using backfat measurements.

Effect of Finishing Rations on Gains, Feed Efficiency and Carcass Characteristics of Swine1

Three feeding trials were conducted to test the effect of several finishing rations upon the rate and efficiency of gain and carcass characteristics of swine. One hundred and forty-seven pigs were individually self-fed in concrete-floor pens from an average weight of 69 lb. to an individual weight of approximately 200 lb. Individual feed lot and carcass data were obtained on all hogs. The following results were noted: Hogs fed corn (grain portion) made significantly faster gains than those fed barley, milo and ½ corn ½ oats; whereas, hogs fed barley made significantly slower gains than those fed corn, ½ corn ½ barley, ½ corn ½ milo, and ¾ corn ¼ oats. Hogs fed corn (grain portion) required significantly less feed per pound of gain than those fed barley, ½ corn ½ milo, or ½ corn ½ oats, while those hogs fed barley required significantly more feed per pound of gain than all treatments except those fed ½ corn ½ oats. Apparently oats could not replace ½ of the corn in a swine finishing ration without seriously lowering average daily gains and increasing feed required per pound of gain. However, oats replaced ¼ of the corn without seriously affecting average daily gains or feed per pound of gain. Hogs fed barley tended to produce leaner carcasses with a lower dressing percent, less backfat, and a higher percentage of lean cuts, whereas those fed milo tended to produce carcasses with a lower yield of lean cuts. Iodine Number of fat from hogs fed the following grains in this study tended to be ranked from low to high as follows: milo, barley, corn and oats.

Influence of Level of Dietary Protein on Live Weight Gains and Carcass Characteristics of Swine

Two hundred twenty-six weanling pigs were fed in four experiments to determine the influence of protein content of otherwise well-balanced rations on various measures of carcass merit and on rate of gain and efficiency of feed utilization. Protein levels compared in three experiments were 18 and 14% initially, each level being reduced three percentage units when the pigs weighed 125 lb. In the fourth experiment initial levels of 16 and 14%, reduced to 11% at 125 lb. were compared with a 12% level fed throughout the experimental period. Carcass measurements included average back fat thickness, length, percent lean and fat and dressing percent. In all but the first experiment the percent of four lean cuts of chilled carcass was measured and the loin eye area was measured in the last two experiments. One hundred ninety-nine carcasses were evaluated. Differences due to protein level were not significant statistically. There were fairly consistent small differences in several measurements in favor of the higher protein levels. There was a highly significant effect of breed (P<.01) on all measures of carcass leanness and fat in each of two experiments in which purebred animals were fed. Initial protein levels of 14, 16 or 18% did not have a significant effect on daily gains. A highly significant decrease (P<.01) in daily gain was observed when weanling pigs were fed a 12% protein diet up to a weight of 125 lb., as compared with those fed 14 or 16% protein. In two experiments there were highly significant differences in daily gain between breeds. The data support the thesis that the genotype of the animal fed is the important factor in carcass leanness and that initial protein levels for weanling pigs within the range of 14 to 18% have only minor effects on carcass quality.

Estimation of Carcass Merit of Swine from Live Animal Measurements

Live animal measurements at 154 days of age and carcass information were obtained on 663 animals during the period 1955–1957, inclusive. Measurements were taken just prior to slaughter on 496 animals. In 1957 live animal measurements were taken at 84, 112, 140 and 154 days of age on 167 animals. An initial study of splitting and cutting errors in hog carcasses indicated that only one side need be cut to yield reliable data. These data indicate that measurements on live animals at 112 to 154 days of age may be used with a reasonable degree of reliability for predicting percent lean cuts at a subsequent slaughter weight of 205–225 lb. Backfat at the loin and body weight were the best indicators of carcass merit. There were indications that some increase in precision might be realized by including additional body measurements. When the measurements were taken at a fairly constant weight, just prior to slaughter, apparently some increase in accuracy was obtained by adding body measurements to an equation containing backfat probes at the shoulder and loin.

Influence of Three Different Feeding Levels During Growth and Gestation on Reproduction, Weight Gains and Carcass Quality in Swine

During a three-year period 90 weanling pigs were grown out at three levels of feed intake on pasture to provide information on carcass characteristics and reproductive phenomena. Average daily gain, daily feed consumed, and feed efficiency calculated from the beginning of the pasture season to market weight (pooled for the three years) was 1.59, 5.29, 3.33; 1.38, 4.32, 3.13; and 1.23, 3.54, 2.88 for full-fed, two-thirds full-fed and one-third full-fed groups, respectively. Carcass data were obtained on 54 of the pigs. Average carcass backfat and percent lean cuts were 1.72, 48.7; 1.73, 49.7; and 1.52, 51.4 for the full-fed, two-thirds full-fed and one-third full-fed lots, respectively. The differences for each trait were significantly different from each other, except for average carcass backfat on the full-fed and two-thirds full-fed groups. Loin eye area or carcass length was not significantly affected by level of feeding. Year had a significant effect on carcass length and percentage of lean cuts (P < 0.01). Reproductive traits (litter size, birth weight, weaning weight and number of pigs weaned) were studied in 36 litters. None of these traits was significantly affected by feeding level; however, year had a significant effect on birth weight and weaning weight (P<0.01). The average gilt weight at farrowing was 480, 427 and 365 lb. for full-fed, two-thirds full-fed and one-third full-fed (P<0.01). Level of nutrition and year interactions were not significantly different for any carcass or reproductive trait studied.