Fat Trim Research Articles

Determination of sensory, chemical and cooking characteristics of retail beef cuts differing in intramuscular and external fat

Top loin (TLS), top sirloin (TSS), and eye of round (EYS) steaks, and loin end (LRR) and blade end (BRR) rib, and eye of round (EYR) roasts were used to determine the effect of USDA quality grade, Choice or Select, external fat trim level, and internal temperature endpoint on sensory, chemical and cooking characteristics. Cuts cooked with external fat required slightly greater cooking times and had higher fat content in the lean than cuts cooked without external fat ( p < 0.05). Regardless of quality grade or external fat trim, increasing internal temperature endpoint resulted in tougher, drier cuts with longer cooking times and greater cooking loss ( p < 0.05). Choice TLS, TSS and LRR were higher ( p < 0.05) in palatability than Select, but quality grade did not affect palatability of BRR, EYS or EYR.

Effects of grilling to 80 °C on the chemical composition of pork loin chops and some observations on the UK National Food Survey estimate of fat consumption

The physical and chemical composition of pork loin chops was investigated, examining the changes that occurred in (i) the whole chop, (ii) the fat tissue and (iii) the lean tissue by grilling to 80 °C. Adjacent 25 mm thick chops, with backfat and rind attached, were cut from loins of 90 kg live weight pigs having a fat thickness (P 2) of 11 mm, representative of current UK production. One chop was analysed fresh by dissection and standard analytical techniques and the other after grilling. Weights of chop (including rind) before and after cooking were 210 and 136 g, respectively. The average weight loss for the whole chop was 35%; the weight loss from fat, 44%, being greater than that from lean, 34%, or rind, 27%, the latter accounting for 14% of the whole raw chop. When expressed conventionally, on a percentage basis, the fat content of the whole rindless chop increased from 22 to 23%, and the fat content of the lean increased from 5.5 to 9%. In absolute terms, based on an initial 100 g, the fat content in the whole chop reduced from 22 to 15 g, with a slight increase in the fat content of the lean, from 5.5 to 6.0 g. It is argued that the National Food Survey (NFS) approach of estimating fat consumption on the basis of the fat content of the raw product is flawed. The terms ‘meat consumption’ and ‘fat consumption’ are misleading since they reflect amounts purchased rather than the amount of meat and fat actually consumed, making no allowance for fat lost during cooking or for subcutaneous fat removed by consumers before consumption. Actual fat consumption from cooked meat and meat products, after allowing for a 25% fat loss during cooking and trimming of visible fat, is estimated at 10.3 g per person per day compared with the NFS estimate of 18.1 g.

Chilling and Trimming Effects on the Microbial Populations of Pork Carcasses

The effects of chilling (normal chill or freeze chill) and trimming (hot fat trim or no fat trim) on the microbial populations of pork carcasses were evaluated. In a two-part study, composited ham, loin, belly, and shoulder samples from 30 pork carcasses had similar aerobic plate counts, averaging 5.5 log10 CFU/cm2. The nofat trim, normal chill procedure typically used in the industry, however, produced higher coliform and Staphylococcus spp. counts (P < 0.05). The hot fat trim, freeze chill treatment had the lowest lactic acid bacteria counts. Only 1 sample in 60 tested positive for Salmonella spp. Vacuum-packaged hams and loins stored at 4°C for 14 days had similar (P > 0.05) aerobic plate counts, lactic acid bacteria and Staphylococcus spp. counts regardless of trim, chill, or the location of treatment, averaging 5.7, 6.3 and 1.4 log10 CFU/cm2, respectively. Hams had higher counts than loins all three days; however, only the difference on day 2 was significant. The desire to reduce microbial populations on pork carcasses as a food-safety issue and the coming implementation of hazard analysis critical control points (HACCP) programs warrants the use of trimming and chilling methods as critical control points or good manufacturing practices and standard operating procedures in the pork slaughter, processing, and packaging industry.

Relative contributions of subcutaneous and intermuscular fat to yields and predictability of retail product, fat trim, and bone in beef carcasses.

Carcass data from one side of 610 steers born from 1988 to 1990 in Cycle IV of the Germ Plasm Evaluation research program were analyzed to develop means for carcass traits and retail product percentages at two fat trim levels (.76 and .00 cm) by yield grade categories. Weights of subcutaneous (s.c.) fat and intermuscular (i.e.m.) fat were recorded separately at each trim level. Quadratic regression curves were plotted for percentages of roast and steak meat (R&S), retail product (RP), and fat trim components relative to incremental changes in USDA yield grade. Prediction equations were developed on a randomly chosen half of the 610 carcasses to predict weights and percentages of R&S, RP, and fat trim using carcass traits obtained at the time of USDA grading and then tested on the remaining half of the carcasses. In addition, prediction equations were developed using s.c. and i.e.m. fat plus carcass traits to evaluate the contribution of each to carcass fabrication yields. Percentage of RP, trimmed to either .76 cm or .00 cm of fat, decreased by an average of 3.5% for each full yield grade increase. Trimming to .00 cm of fat resulted in about 5.3% less RP compared to trimming to .76 cm. A prediction equation for percentage of RP trimmed to .00 cm using adjusted fat thickness, carcass weight, longissimus muscle area, and percentage of kidney knob had an R2 value of .54. The variations in percentage of R&S and percentage of RP at both trim levels were reduced by removing s.c. fat trimmed to .76 cm; however, considerable variation still existed. Subcutaneous fat expressed as a percentage of the sum of i.e.m. and s.c. fat increased as yield grade increased, but the percentage of i.e.m. fat was higher than the percentage of s.c. fat for all yield grades. On the basis of partial correlation coefficients, i.e.m. fat was approximately twice as important as s.c. fat in accounting for variations in fabrication yields.

Retail yield and fabrication times for veal as influenced by purchasing options and merchandising styles.

Twenty-nine selected styles of subprimals or sections of veal were obtained from a commercial facility to assist in the development of a support program for retailers. They were fabricated into bone-in or boneless retail cuts and associated components by trained meat cutters. Each style selected (n = 6) was used to generate mean retail yields and labor requirements, which were calculated from wholesale and retail weights and processing times. Means and standard errors for veal ribs consisting of five different styles (n = 30) concluded that style #2, 7-rib 4 (10 cm) x 4 (10 cm), had the lowest percentage of total retail yield (P < .05) owing to the greatest percentage of bone. Furthermore, rib style #2 required the longest total processing time (P < .05). Rib styles #3, 7-rib chop-ready, and #5, 6-rib chop ready, yielded the greatest percentage of total retail yield and also had the shortest total processing time (P < .05). Within veal loins, style #2, 4 (10 cm) x 4 (10 cm) loin kidney fat in, had the greatest percentage fat (P < .05). Loin styles #2 and #3, 4 (10 cm) x 4 (10 cm) loin special trimmed, generated more lean and fat trimmings and bone, resulting in lower percentage of total retail yields than loin style #1, 0 (0 cm) x 1 (2.5 cm) loin special trimmed (P < .05). Results indicated that bone-in subprimals and sections required more processing time if fabricated into a boneless end point. In addition, as the number of different retail cuts increased, processing times also increased.

Deep inferior epigastric artery (DIEA) skin flap: clinical experience of 15 cases

Skin flaps devoid of rectus muscle, raised on a single musculocutaneous perforator (14 cases), and on two musculocutaneous perforators (1 case) of the deep inferior epigastric artery (DIEA) were used in 14 patients to cover various defects during a period of 3 years. The flaps were raised on the perforator arising slightly lateral to the centre of the muscle below the umbilicus, which is a sub-branch of the lateral branch of DIEA. The defects were located on the upper limb in four, the lower limb in nine, and the scalp and forehead in the remaining two cases. In one patient, the flap was preexpanded for 4 weeks prior to transfer. The longest flap was 40 x 12 cm, and the widest flap was 30 x 18 cm in dimension. All donor defects were closed primarily. Two flaps were lost due to venous thrombosis on the fourth postoperative day. Tip necrosis was observed in two flaps, both of which were salvaged from venous thrombosis at 36 hours and 5 days postoperatively. The remaining 11 flaps survived completely. The DIEA skin flap was found to provide the following benefits: (1) the largest available skin flap where the donor site could be closed primarily; (2) decreased possibility of abdominal wall weakness and hernia formation; and (3) potential of obtaining a thin flap either by trimming of the subcutaneous fat or by preexpansion.

Relationship of visual assessments of feeder lamb muscularity to differences in carcass yield traits.

We examined the relationship between visual differences in muscle thickness among feeder lambs and subsequent differences in carcass composition. Medium-framed, crossbred feeder lambs (n = 120) were selected at two commercial feedlots to exhibit distinct phenotypic differences in muscularity. The lambs were assigned scores (ranging from 1 to 9; 1 = extremely thin, 5 = average, 9 = extremely thick) for muscle thickness and were sampled serially on d 0, 14, 28, and 42 of the trial. After recording yield grades, one side of each carcass was deboned, and the soft tissues from the entire side were ground, sampled, and analyzed for lipid and moisture content. The opposite side was fabricated into boneless, closely trimmed (.25 cm maximum fat depth) subprimal cuts. When lambs of the same frame size were compared at the same live weight, greater muscle thickness was associated with greater (P < .05) fat-free muscle mass. Correspondingly, thickly muscled lambs produced carcasses of a given weight that had a higher (P < .05) composite yield of lean meat and a lower (P < .05) proportion of trimmable fat compared with carcasses of thinly muscled lambs. When comparisons were made at the same percentage of extractable fat in the carcass, greater muscle thickness was associated with heavier (P < .05) live and carcass weights, increased (P < .05) fat-free muscle mass, and increased (P < .05) weights of trimmed, boneless subprimal cuts. Results suggest that visual assessments of muscle thickness in feeder lambs, as applied in this study, are indicative of commercially important differences in carcass yields of lean meat.

Adipose tissue partitioning of limit-fed beef cattle and beef cattle with ad libitum access to feed differing in adaptation to heat.

We compared fat distribution and lipoprotein lipase (LPL) activity in steers differing in adaptability to the subtropics. Steers were fed a grain diet (3.13 Mcal ME/kg DM) at limited (150 kcal ME x kg[-.75] x d[-1]; .23 kg ADG) or ad libitum levels for 140 d, then slaughtered. Sixteen British- (8 Angus, 8 Hereford; S), 16 Boran- (R), 16 Brahman- (B), and 16 Tuli- (T) cross steers from MARC III composite cows were used. Adipose tissue samples from perirenal, omental, and subcutaneous depots were analyzed for LPL activity. Carcass measurements including omental, external, and seam fat trim from 1/ 2 of the carcass were measured. Subcutaneous fat had greater (P < .05) LPL activity than fat from the other depots. Generally, there were no differences (P > .05) in fat distribution for steers fed at limited levels. Means for ADG, slaughter weights, carcass weights, yield grades, and carcass lipid weights for S and B fed for ad libitum intake were greater (P < .05) than those for T and R. Marbling was greatest (P < .05) for S and did not differ (P > .05) for the other breeds with ad libitum intake. Factor analysis of fat depots for animals with ad libitum intake indicated that Bos taurus cattle differing in adaptation to heat deposited fat differently; S deposited greater (P < .05) proportions of carcass fat and T deposited greater (P < .05) proportions of internal fat. It seems that accumulation of internal fat is detrimental for ADG for Bos taurus cattle.

Crossbreeding dual-purpose cattle for beef production in tropical regions

Six breed types groups of six steer calves each were used to observe differences in growth and carcass traits: F1 Brown Swiss ( F1BS), F1 Holstein ( F1HO), F2 Brahman ( F2BR), F2 Criollo Rio Limon ( F2CRL), purebred Criollo Rio Limon ( CRL), and Perija Mosaic ( PMO). After 404 days of grazing, the heaviest F1BS and F2BR steers were different from F1HO and CRL counterparts ( p < 0.05) in slaughter weight. F2BR dressed higher and had better muscle conformation scores than F1BS, F1HO, F2CRL and CRL ( p < 0.05). F1BS had the thickest backfat (0.5 cm) but only differed ( p < 0.05) from F1HO (0.3 cm). Rib eye area, marbling score, carcass maturity, quality or yield grade, boneless cut percentages, bone percentage or percent trimmable fat did not vary among breed types. All steers were within the A maturity level and graded Standard. Results indicate the importance of feeding dual-purpose steers to heavier weights to please industry preferences.

Biceps femoris and rump fat as additional ultrasound measurements for predicting retail product and trimmable fat in beef carcasses.

One hundred ninety-eight steers of Angus and Hereford breeding were evaluated ultrasonically for fat thickness over the 12-13th rib (UFAT), fat thickness over the rump (URUMP), 12-13th longissimus muscle area (UREA), and depth of the biceps femoris (UROUND) before slaughter. Carcass measurements associated with the USDA yield grade were also obtained. Carcasses were fabricated into closely trimmed (.32 cm fat), boneless subprimals. Regression procedures were used to predict weight and the percentages of retail product and trimmable fat. Final weight (FINALWT) accounted for most of the variation when predicting kilograms of retail product and trimmable fat, with R2 values of .836 and .435, respectively. As single predictors URUMP and UFAT accounted for most of the variation when predicting the percentages of retail product and trimmable fat with R2 values of .244 and .220, respectively. Adding URUMP to equations that included FINALWT, UREA, and UFAT increased R2 values for percentage of retail product from .175 to .318 and for weight of retail product from .847 to .865, whereas the addition of UROUND did not appreciably increase R2 values for the same models. Adding URUMP and UROUND to the model of FINALWT, UREA, and UFAT to predict kilograms and the percentage of trimmable fat increased R2 values from .530 to .610 and from .254 to .360, respectively. Models using live-animal measurements to predict weight and the percentage of retail product gave R2 values equal to models using the actual measurements found in the USDA Yield Grade equation.

Characterization of different biological types of steers (cycle IV): wholesale, subprimal, and retail product yields.

Carcass cut-out yields of 888 steers obtained from mating Hereford and Angus cows to Hereford or Angus (HA), Charolais (Ch), Gelbvieh (Gb), Pinzgauer (Pz), Shorthorn (Sh), Galloway (Gw), Longhorn (Lh), Nellore (Ne), Piedmontese (Pm), and Salers (Sa) sires were compared. Data were evaluated at constant age (426 d), carcass weight (324 kg), fat thickness (1.2 cm), fat trim percentage (23%), and marbling (Small(00)) end points. Piedmontese-sired steers excelled in total retail product and fat trim percentages at all slaughter end points except at the 23% fat trim end point. At an age end point, percentage of retail product was greater in steers sired by Continental European breeds (Gb, Ch, Sa, Pz; 63.3 to 65.5% at 0 cm trim) than in steers sired by British breeds (Sh, HA; 60.1 to 61.0%). Piedmontese-sired steers, which were expected to carry one copy of a major gene for muscle hypertrophy, had the highest (P < .05) retail product yields at an age end point (69.7%). At an age end point, although carcass weights were significantly heavier (P < .05) for Charolais-sired steers than for Piedmontese-sired steers, lean growth rate, as reflected by totally trimmed retail product at 426 d, was similar (P > .05) for Piedmontese and Charolais-sired steers. Differences among sire breeds were small for retail product percentage at marbling, fat thickness, and fat trim end points. Ranking of sire breeds for age-constant weight of retail product was as follows: Ch, Pm, Gb, Sa, Ne, Pz, HA, Sh, Gw, and Lh. Sire breed differences in wholesale and subprimal cut yields were similar to total retail product differences. Piedmontese-sired steers produced the most muscular, leanest, and highest-yielding carcasses, and HA- and Sh-sired steers produced the fattest, lowest-yielding carcasses.

Performance, carcass, and palatability traits for cull cows fed high-energy concentrate diets for 0, 14, 28, 42, or 56 days.

Cull cows, thin to moderate in initial condition scores, were randomly assigned within breed to slaughter groups and fed a high-concentrate diet for 0, 14, 28, 42 or 56 d (n = 40). Carcass data were collected, and one side of each carcass was fabricated into boneless subprimals, lean trimmings, fat, and bone. Live and carcass weights, ADG, and dressing percentage increased through 28 d of feeding (P < .05), and lean firmness increased (P < .05) through 42 d of feeding. Adjusted preliminary yield grades and final yield grades increased (P < .05) with feeding, but not to levels requiring knife trimming of fat. Fat color became whiter (P < .05) but marbling was not affected (P > .05) by feeding. Weights of fat-free lean, fat, and bone and percentages of fat in soft tissues of cow carcasses increased (P < .05) by 28 d on feed. Overall steak tenderness was higher (P < .05) for cows fed 56 d than for cows fed 0 or 14 d. Warner-Bratzler shear force was not affected by feeding. Amounts of soluble collagen increased (P < .05) in the longissimus muscle between 0 and 28 d on feed, and total collagen decreased (P < .05) in the biceps femoris muscle between 0 and 42 d on feed. Continental European cow carcasses yielded more fat-free lean and less fat (P < .05) and dairy cows generally provided the most tender product across all slaughter periods. In general, sensory tenderness and yields of cow carcass components increased without requiring excessive trimming of fat by feeding cull beef and dairy cows for periods up to 56 d.

Phenotypic characterization of Rambouillet sheep expressing the callipyge gene: II. Carcass characteristics and retail yield.

Paternal half-sibling Rambouillet ram lambs (n = 18) representing two muscle phenotypes were slaughtered at 54.5 kg to evaluate carcass characteristics and composition. Lambs were produced from a sire that was heterozygous for the callipyge gene. Carcasses were broken into wholesale and retail cuts to evaluate percentage bone-in retail yield of carcasses at various fat trim levels and percentage of boneless retail cuts. Retail cuts were trimmed to .6 and then to 0 cm fat trim and bones were removed to determine boneless, closely trimmed retail cut yield. Chemical composition was determined using proximate analysis. Lambs expressing the callipyge gene had higher dressing percentages (57.3 vs 53.9), leg (14.4 vs 11.0) and conformation (14.4 vs 11.0) scores, and larger longissimus muscle (LM) areas (17.6 cm2 vs 10.3 cm2). All other carcass measurements were similar between phenotypes except marbling score, which was higher (417.8 vs 325.6) for controls. Lambs expressing the callipyge gene had a higher (40.2 vs 32.9) percentage boneless retail yield than controls. Retail yield of the boneless shoulder did not differ between phenotypes (8.9 vs 8.0). All other percentages of boneless retail cuts were higher (P < .02) for lambs expressing the callipyge gene. Carcasses from lambs with the callipyge gene had higher protein (16.6 vs 15.2), moisture (63.6 vs 58.6) and ash (.85 vs 77) percentages and lower fat (18.9 vs 25.4) percentages than controls. These data suggest that ram lambs expressing the callipyge gene have an advantage in retail yield and carcass conformation when compared to normal-muscled half-siblings.

Variation in and effects of prefabrication fat trimming on yields and prediction equation accuracies of retail product and fat trim (1996)

Carcass data from one side of 1,149 steers born from 1986 to 1990 were analyzed to develop means for carcass traits and retail product percentage by yield grades. Carcasses from 610 of these steers born from 1988 to 1990 were fabricated to two fat trim levels (.30 and .00 in.), with subcutaneous fat and intermuscular (internal) fat weighed separately. Subcutaneous fat from the primal round, loin, rib, chuck, brisket, and flank in excess of .30 in. plus the kidney knob were considered to constitute an industry "˜hot-fat trim equivalent' (HFTE). Quadratic regression curves were plotted for percent retail product (RP) and percent fat trim (FT) vs. USDA yield grade. In addition, prediction equations were developed for weights and percentages of RP and FT that could be used in plants that do hot-fat trimming and quality grading of carcasses. Percentage of RP, trimmed to either .30 or .00 in. of fat, decreased an average of 4% for each full yield grade increase. Trimming to .00 in. of fat instead of .30 in. reduced RP about 5.5%. The average percentage of HFTE for a yield grade 3.0 carcass was 8.4%. The range in percentage of RP at both trim levels was reduced by trimming fat to an HFTE basis , but considerable range still existed. The range in percentage of internal (seam) fat across yield grades was greater than the range in percentage of HFTE. An equation to predict percentage RP in HFTE carcasses using percentage of hot fat trim, carcass weight, ribeye area, and marbling score had an R2 of .75, which was considerably higher than that for an equation using USDA yield grade traits from untrimmed carcasses (R2=.54). The high accuracy of our prediction equation suggests that the industry could use it to accurately predict closely trimmed RP percentage of hot-fat trimmed carcasses.

Characterization of biological types of cattle (Cycle IV): carcass traits and longissimus palatability.

Carcass and longissimus thoracis palatability traits from 888 steers obtained from mating Hereford and Angus cows to Hereford or Angus (HA), Charolais (Ch), Gelbvieh (Gb), Pinzgauer (Pz), Shorthorn (Sh), Galloway (Gw), Longhorn (Lh), Nellore (Ne), Piedmontese (Pm), and Salers (Sa) sires were compared. Data were adjusted to constant age (426 d), carcass weight (324 kg), fat thickness (1.2 cm), fat trim percentage (23%), and marbling (small00) end points. At a constant age of 426 d, carcasses from Ch steers were heaviest (P < .05) and Gw and Lh carcasses were lightest (P < .05). Adjusted fat thickness was greatest (P < .05) on carcasses from HA and least (P < .05) on carcasses from Ch, Gb, Lh, and Pm steers. USDA numerical yield grades were lowest (P < .05) for carcasses from Pm and highest (P < .05) for carcasses from HA, Ne, and Sh steers. Marbling scores were highest (P < .05) for carcasses from HA, Pz, and Sh and lowest (P < .05) for carcasses from Ch, Ne, and Pm steers. Longissimus thoracis from Pz had a lower (P < .05) shear force than that from all other breeds except HA, Gb, and Pm. Longissimus thoracis of carcasses from Ne steers was least (P < .05) tender. Adjustment of traits to various end points resulted in some changes in sire breed differences depending on the end point and the trait being considered but had little effect on palatability traits. Carcasses from Pm-sired steers provided the most desirable combination of carcass and longissimus palatability traits.

Hot-Fat Trimming Effects on the Microbiological Quality of Beef Carcasses and Subprimals

Subcutaneous and kidney-pelvic-heart fat were trimmed from one side of each beef carcass (n = 9) immediately after cold water washing. Both sides were sampled for aerobic plate counts (APCs) before being moved to the chill room (0 h) and after 72 h of cold storage. The mean APCs (log10 colony-forming units (CFU)/cm2) of trimmed (HFT) sides at 0 or 72 h were not different (P > 0.05) from those of the nontrimmed (NFT) sides. All sides at 72 h had reduced microbial counts compared to 0 h. By 72 h, HFT sides had numerically lower counts than NFT sides, indicating that the microbial reduction effect of the chill temperature may have been greater on fat-trimmed carcasses than on nontrimmed carcasses. Subprimals from HFT and NFT sides that were trimmed to 0.64-cm fat thickness were microbiologically analyzed before (0 days) and after (14 days) vacuum storage. APCs of all subprimals were slightly reduced after 14 d; however, no difference (P > 0.05) occurred in treatment effect. The mean APC was higher for HFT-side subprimals than for NFT-side subprimals at both 0 and 14 days. This difference probably was due to the fat trimming required for NFT-side subprimals at day 0 as compared to minimal or no trimming of HFT-side subprimals. Those HFT subprimals which were not subsequently trimmed may have picked up additional microorganisms from contact surfaces during fabrication. Based on our trimming protocol, although HFT did not show any negative impact on the microbial quality of carcasses, the higher APC of HFT-side subprimals indicated that extensive trimming may not be effective in improving the microbial quality of meat.

Real-time ultrasonic measurement of fat thickness and longissimus muscle area: I. Description of age and weight effects.

Serial ultrasonic measures of fat thickness (FTU) and longissimus muscle area (LMU) were taken on 180 feedlot steers representing 11 sire-breed groups at two 60-d intervals. Cattle then were slaughtered in four groups of 45 at 21-d intervals with ultrasonic measures taken at each interval. Analyses of variance indicated weight (WT) effects (P < .001) for all FTU measures and many of the LMU measures. Age was a source of variation (P < .05) for FTU and LMU over the first five measurement dates. Sire-breed (SBD) effects (P < .001) were prevalent for all FTU estimates and early LMU predictions. Some dam line and SBD x dam line interactions were detected (P < .1) for the FTU and LMU estimates. Age effects were described quadratically (P < .001) when FTU and LMU were regressed on age (R2 = 47 and 68%, respectively). When FTU and LMU were regressed on WT, effects were described quadratically (P < .001) with R2 values of 46 and 72%, respectively. Animals then were assigned to one of four biological types (BT) based on percentage of retail product (0-mm fat trim) using discriminant cluster analysis. Within BT, ultrasonic variables were regressed on age. Quadratic effects (P < .01) were detected for both FTU and LMU. Weight also contributed to variation observed in both ultrasonically measured variables for all BT (P < .001). These data indicate that changes in fat and muscle size as affected by age and weight are detectable using serially collected ultrasound measures. Furthermore, the age and weight relationships of predicted FTA and LMA varied across the four biological types. This suggests a need for derivation of biological type-specific age and(or) weight adjustment equations for cattle evaluation purposes.

Real-time ultrasonic measurement of fat thickness and longissimus muscle area: II. Relationship between real-time ultrasound measures and carcass retail yield.

Feedlot steers (n = 180) representing 11 sire-breed groups were ultrasonically measured for fat thickness (FTU) and longissimus muscle area (LMU) at two 60-d intervals during the feeding period and four 21-d intervals corresponding to serial slaughter dates to predict carcass retail yield parameters. Two fat trim levels, 8 and 0 mm, were used to calculate percentage of trimmable fat (FAT8P and FAT0P) and retail product percentage (RPD8P and RPD0P) for each carcass. Regression techniques were used to evaluate best-fit equations that explained variation in retail product components. When FAT8P, FAT0P, RPD8P, and RPD0P were regressed on USDA yield grade (YG), R2 values ranged from 75 to 76% (P < .001). Comparatively, when live animal predictors of YG components (FTU, LMU, and final live weight) were used as the independent variables, equations predicting retail yield had R2 values of 61 to 65% (P < .01). Equations using final FTU as the independent variable explained 58 to 64% (P < .001) of the variation in FAT8P, FAT0P, RPD8P, and RPD0P. Equations with FTU, LMU, and either WT, AGE, marbling, or quality grade resulted in R2 values similar to those with only FTU, indicating the strong influence of fat on retail yields. These results indicate that ultrasonic predictors explained about 10% less variation in retail product percentage than did carcass measures.

The Impact of Operator Error Using Optical Probes to Estimate Pork Carcass Value

Live-weight pricing is the dominant system currently used by pork packing firms to procure hogs (Jekanowski and Akridge). Under this system, value is determined by multiplying the live weight of the animal by the live-weight price. Assuming that there is little variation in physical characteristics of animals and/or end-use requirements for the carcass are not important, live-weight pricing is an appropriate method for valuing live hogs. For this scenario, a liveweight procurement program is simple and low cost. However, changing consumer preferences for leaner pork products, genetics which make possible the production of leaner hogs, new swine production management practices, and new technologies for measuring lean content of pork carcasses have shifted pork production away from a commodity orientation to a focus on value-added, differentiated products (Boland, Foster, and Akridge). In response to consumer desire for leaner protein sources, there has been a reduction in fat at the retail level. Buege et al. reported that pork cuts currently available at the retail level have 31 percent less fat compared to 1982 pork cuts, primarily because packers have begun trimming carcasses closer. Using a knife to trim external fat is costly, so packers prefer that the amount of trimmable fat be at a minimum. Morgan et al. reported that packers and processors identified excessive fat as their primary concern in the processing of pork carcasses and primal cuts.

Effects of breed type and accelerated fat removal on subprimal yields and carcass values

Nine Brown Swiss and nine English crossbred steers representing the industry standard were slaughtered to determine the effects of cattle type and hot fat removal on subprimal yields and carcass value. After dressing, cod fat, kidney, pelvic, and heart fat (KPHF), and subcutaneous fat thicker than .6 cm was removed from the right side of each carcass (HFT). The left side was not hot-fat trimmed (NFT). Both sides were fabricated into subprimal cuts with no more than .6 cm of subcutaneous fat. Carcass side values were adjusted to a 300-kg chilled carcass weight basis. All comparisons were made for the carcasses using a USDA Select quality grade end point. English crossbred steer carcasses had more (P < .05) subcutaneous fat on the loin and chuck and more (P < .05) total hot fat trim, when KPHF was not included, than Brown Swiss steers (P < .05). Brown Swiss steers had more (P < .05) KPHF. Hot-fat trimmed sides had higher (P < .05) percentage yields from the chuck, brisket, foreshank, rib, plate, round primal cuts, and most of the subprimal cuts than NFT sides, but the primal loin percentage was higher (P < .05) in the NFT sides. The total subprimal cuts yield was approximately 5% higher for the HFT sides than for the NFT sides, and the total fat trim during fabrication was more than 6% less. When the value of the sides was calculated from unadjusted weights, the NFT sides were approximately $26.50 more valuable than the HFT sides.(ABSTRACT TRUNCATED AT 250 WORDS)