History of the meat animal evaluation contest: a pedagogical stimulant.

A century ago students were exposed to livestock judging and meat judging, though each was taught as an independent entity. Fifty years ago universities started combining subjects involving the evaluation process, whether characteristics involved traits of the live animal or those related to meat value. Universities developed a meat animal evaluation contest (MAEC) that included breeding livestock, market livestock, and meat products. Using production records, students culled, ranked, priced, and answered questions about breeding and market cattle, swine, and sheep. For market livestock, ranks and values were scored on carcass data after the livestock were harvested. Students graded, ranked, answered questions, and priced meat products. A communications component involved students being given a problem to be discussed as a group presentation. In 1964, the first MAEC was conducted at Rath Packing Co., Waterloo, IA, and included 40 students. In 1967, the contest was held at The Farmbest Co. and IBP of Denison, IA, and included 87 students. In 1968, the MAEC moved to the Knights of Ak-Sar-Ben, Omaha, NE, and by 1988, 187 students (22 universities) competed. In 1995, the MAEC moved to the United Stockyards Co., St. Joseph, MO. Starting in 2004, it moved to various universities (South Dakota State University, Oklahoma State University, University of Nebraska, and Texas Tech University). The MAEC has stimulated students to better learn and understand the details of meat animal evaluation and has encouraged the development of evaluation courses as well as satellite and symposia programs. To date, over 6,000 students representing 40 universities have participated.

The Animal Sciences Academic Quadrathlon: history, current status, and recommendations.

The Animal Sciences Academic Quadrathlon (AQ) provides opportunities for teams of undergraduate animal and dairy science students to participate in regional American Society of Animal Science (ASAS)/American Dairy Science Association (ADSA) meetings and to collectively exhibit their knowledge and talents competitively in 4 categories: 1) solving practical, hands-on, laboratory-type problems; 2) providing written answers to essay-type questions about principles and concepts; 3) preparing and communicating orally and extemporaneously topics of current animal science interest; and 4) quickly responding to short-answer questions provided in the form of double-elimination quiz bowls. Each team is selected by winning the local AQ at their university. Overall and individual category winning teams are recognized, but team rankings are not emphasized. The ASAS/ADSA members provide leadership for organizing and conducting the AQ, and ASAS and each university provide travel expenses for students. The ultimate purpose is to stimulate academic excellence among undergraduate students and for the students to attend ASAS/ADSA regional scientific meetings to meet faculty and students and to attend scientific research presentations. The purpose of this document was to provide a history of the event and to make recommendations for its improvement. The AQ was conceived in 1967. During the next 10 yr, an ASAS committee developed procedures for a trial AQ held in 1980 at the ASAS Midwestern Section, Kansas State University-Manhattan, and in the next year the first official AQ was held at the ASAS Midwestern Section at the University of Nebraska-Lincoln. Starting in 1985, AQ programs were initiated at the other 3 ASAS sectional meetings, and an estimated 50,000 students representing 60 universities have participated in AQ programs since that time. If the AQ is to continue its improvement over time, it will greatly depend on sustained ASAS/ADSA faculty interest and support, as well as greater adherence to the original AQ procedures.

The relative effect of dietary energy density on repleted and resting muscle glycogen concentrations.

The aim of this study was to assess the effect of dietary energy density on the glycogen concentration of bovine gluteus medius (GM) and longissimus thoracis et lumborum (LTL) muscles in castrated and intact males. Cattle received diet C (90% whole corn and supplement: 10% alfalfa haylage) or diet AH (100% alfalfa haylage) in three experiments involving a 2×2 factorial cross-over design. Cattle fed an AH diet for 70 days prior to the first experiment had high glycogen concentrations in the GM (129±9.9 mmol/kg) and LTL (108±7.6 mmol/kg) at the first biopsy session. These concentrations are similar to GM (133±6.2 mmol/kg) and LTL (105±5.8 mmol/kg) glycogen concentrations when these cattle subsequently received diet C for 30 or 37 days. Diet C increased muscle glycogen concentration, but the consistency of the increase in glycogen was dependent on the initial concentration. When the initial glycogen concentration was depleted to 50 µmol/g with one subcutaneous injection of adrenaline, repleted glycogen concentration was higher for diet C than AH (P<0.01) in all comparisons involving GM and LTL muscles of both steers and bulls. For resting muscle glycogen, the GM of bulls was more sensitive to the effect of diet C than the bull LTL or either muscle in steers. Diet was not a major determinant of resting muscle glycogen concentration. The ultimate pHs of GM, LTL and semimembranosus (SM) were not affected by diet and residual glycogen was lower in LTL of bulls fed either diet than for LTL of steers fed AH. Diet and male status did not affect residual glycogen in GM or SM.

Glycogen concentrations in bovine longissimus dorsi muscle.

The aim of this study was to assess the effect of location within bovine longissimus dorsi (thoracis et lumborum) muscle (LTL) when determining glycogen concentration. Six locations in Angus heifers were sampled post mortem (EXP-1) and eight locations in live Charolais crossbred steers were biopsied (EXP-2). In EXP-1, there was more glycogen in the animals' left LTL (64.1±1.6 mmol/kg) versus the right LTL (57.0±1.6 mmol/kg) (P<0.05). Locations along the cranial-caudal axis within LTL did not differ in glycogen concentration. Results for EXP-2 did not confirm the sidedness effect. Instead, it showed that glycogen concentration was lower at the cranial sampling locations near the 10th rib (89±2.5 mmol/kg) than at the middle (97±2.0 mmol/kg) or caudal locations (96±1.9 mmol/kg) (P<0.005). Taking lactate accumulation into account (glycolytic potential) rendered those differences insignificant. Nevertheless, the tendency remained clear. The potential for dilution of glycogen by intramuscular fat deposits is discussed. The results indicate that one needs to be cautious in performing repeated sampling on bovine LTL.

Use of electrical conductivity to predict water-holding capacity in post-rigor pork.

This study was designed to re-examine the interrelationships among ultimate pH (pH(u)), electrical conductivity (EC) and water-holding capacity (WHC), and to test if EC, using one of two EC instruments, and pH(u) can be used to predict WHC. The % drip (PD) was used as measure of WHC. Forty-seven pork loins were classified either as PSE (pale, soft, exudative), RSE (reddish-pink, soft, exudative), RFN (reddish-pink, firm, non-exudative) or DFD (dark, firm, dry), based on L* values, PD and pH(u.) The measurement of EC, conducted using the instrument developed at the University of Wisconsin-Madison (UW-EC) was highly correlated to PD at 24 h post mortem (CD=66%), but the pH (NWK) measure of EC was not as highly related to WHC as UW-EC. The predictive value of pH(u) and EC for WHC were similar. When 47 samples were divided into three different groups, such as low (< 2% drip), medium (2-6% drip) and high (> 6% drip) drip loss, UW-EC alone grouped 80% of the samples correctly. Thus, EC seemed to be an accurate predictor of WHC in pork muscle when measured at 24 h post mortem. It is conceivable that EC can be used independently, or with even better success in combination with pH(u), to classify WHC of pork carcasses.

Effect of ion fluid injection on beef tenderness in association with calpain activity.

Sodium pyrophosphate plus sodium chloride (PPi) was injected into pre-rigor, hot boned biceps femoris (BF) and semimembranosus (SM) muscle from 12 heifer carcasses. The PPi injection caused higher pH values between 10 and 48 h post-mortem than found in the controls for both muscles (P<0.05). PPi injection resulted in faster decreases in the activities of µ-calpain and calpastatin than in the control for both muscles with time post-mortem (P<0.05). There were significant differences between treatments in both the BF and SM (P<0.05). There was evidence that PPi-injection elevated pH, and accelerated activation of calpains, resulting in improved tenderness. The rates of degradation of titin and troponin-T as well as the appearance of 95 and 30 kDa peptides were faster in the PPi-injected muscles than the controls. PPi-injection elevated muscle pH, which was attributed to acceleration of the calpain activation. It is concluded that PPi-injection improved beef tenderness by accelerating activation of calpain.

Glycolytic potential of red, soft, exudative pork longissimus muscle.

Red, soft, exudative (RSE) pork is red as "normal" pork and exudative as PSE pork. The origin of RSE quality is unknown. In the present study, we determined whether the occurrence of RSE pork is related to the presence of the RN (Rendement Napole) gene. A glycolytic potential [= 2 x (glucose + glycogen + glucose-6-phosphate) + lactate] of > 180 micromol lactate/g of meat was used as indicator for presence of the RN gene. At 1 d postmortem, pork loin samples were collected at a commercial slaughter plant, and meat quality characteristics and glycolytic potential were determined. Glycolytic potential of RSE pork (n = 42) was higher (P < .01) than that of RFN (red, firm, nonexudative) pork (n = 25): 137 vs 110 micromol lactate/g of muscle. The glycolytic potential of PSE pork (n = 28) was 161 micromol lactate/g of muscle, which was higher (P < .01) than the glycolytic potential of RFN or RSE pork. Using a glycolytic potential of 180 micromol lactate/g of muscle as suggestive for the presence of the RN gene, four (10%) of the RSE samples were from RN carriers. By the same criterion, the PSE group contained nine (32%) RN gene carriers. These results suggest that the occurrence of RSE quality is not related to the presence of the RN gene.

Using pork to teach students quality variations and how they are measured. 1998 UW-AS-305 Class.

Using a total of eight pork loins representing DFD (dark, firm, and dry) and PSE (pale, soft, and exudative) conditions, 35 students conducted a series of objective and subjective measurements to demonstrate extremes in meat quality in a single 2-h laboratory. Students learned to objectively assess appearance, water-holding and water-binding capacity, ultimate pH (pHu), and shear force (cooked samples) by operating seven commonly known laboratory instruments. They also learned how to prepare and present samples for organoleptic analysis using hedonic and triangle tests. Finally, the students learned the factors related to meat quality and how extremely they can vary. Within one laboratory, they observed that DFD, when compared with PSE, averaged 1.5 units higher in pHu, 4.7% (absolute) less drip loss, bound 136% (absolute) more water, was darker in color (26 units lower L* value), was firmer with a more attractive structure requiring 1 kg/cm less force to shear, and was superior in organoleptic properties (overall 21% more desirable). Having 35 replicates to use for the data set, the results illustrated statistically significant variations in meat-quality traits and how they could be objectively measured. Nine months later, 12 of the students were surveyed. It was their perception that the laboratory was not any more effective than other laboratories in the same class, but they were able to remember 85% of the methods used to measure quality; about twice that of other methods taught in other laboratory sessions.

The relationship of sarcoplasmic and myofibrillar protein solubility to colour and water-holding capacity in porcine longissimus muscle.

In order to investigate the relationship of sarcoplasmic and myofibrillar protein solubility to colour and water-holding capacity (WHC) in pork, 60 loins were selected to represent the quality classes: PSE (pale, soft, exudative), RSE (reddish-pink, soft, exudative), RFN (reddish-pink, firm, non-exudative) and DFD (dark, firm, dry). PSE samples exhibited lower (p<0.05) protein solubility (sarcoplasmic, myofibrillar and total) compared to the other quality classes. RSE samples exhibited lower (p<0.05) sarcoplasmic protein solubility compared to DFD samples. RSE, RFN and DFD samples had similar myofibrillar and total protein solubilities. Sarcoplasmic protein solubility explained 71% of the variation in lightness with a linear decrease in L* value. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) gels of the sarcoplasmic and myofibrillar samples distinctly showed the association of some sarcoplasmic proteins with the myofibrillar protein fractions in PSE and RSE samples. The sarcoplasmic proteins which precipitated were phosphorylase, creatine kinase, triose phosphate isomerase and myokinase for PSE and phosphorylase for RSE samples. Pork colour is highly correlated with precipitation of sarcoplasmic proteins while WHC is affected by denaturation of myofibrillar proteins (PSE samples) and lower ultimate pH (PSE and RSE samples).

Low voltage electrical stimulation of lamb carcasses: effects on meat quality.

The effects of an early post mortem low voltage electrical stimulation (28 V, 60 Hz) on biochemical changes and on final tenderness in muscles Longissimus thoracis et lumborum and Semimembranosus from lamb carcasses were studied. It was shown that electrical stimulation accelerated the glycolytic process resulting in a significant fall in pH during the first 6 h post mortem in both muscles examined and in a significant reduction in adenosine triphosphate (ATP) content in muscle Longissimus thoracis et lumborum. The effect of electrical stimulation on tenderness was recorded by measuring shear force values 2 and 7 days post mortem. Tenderness was significantly improved by electrical stimulation for the Longissimus thoracis et lumborum both at 2 and at 7 days post mortem, while for Semimembranosus electrical stimulation significantly increased tenderness just at 7 days post mortem.

Can pale, soft, exudative pork be prevented by postmortem sodium bicarbonate injection?

Previous attempts at eliminating the problem of PSE pork by genetic selection or rapid postmortem cooling have been only partially successful. A new approach, namely, postmortem injection of sodium bicarbonate (SBC), was tested on halothane-positive gilts. Sixteen pigs were used to establish a suitable SBC concentration. At approximately 15 min after death, the longissimus of one side of the carcass was injected with 10% (by weight) of .2 to .4 M SBC solutions containing .7% NaCl (wt/vol). All concentrations resulted in a higher ultimate pH, improved muscle color, and reduced drip loss. In a second experiment, with 23 pigs, .3 M SBC was injected into the longissimus and the biceps femoris at either 15 min or 24 h after death and with or without inclusion of .7% NaCl (wt/vol). Compared with controls, the 15-min SBC + NaCl injected samples had darker color (L* of 47 vs 53 in controls), higher ultimate pH (5.6 vs 5.3), lower drip loss (5% vs 10%), and increased protein solubility (140 vs 115 mg/g). Injection at 24 h reduced drip loss (from 10% to 5.7%) but did not correct the color defect. The SBC alone and SBC + NaCl treatments had essentially the same effects in reducing drip loss, increasing ultimate pH, and improving color; but the SBC-NaCl injected samples had improved juiciness and flavor compared with SBC. Early postmortem sodium bicarbonate injection seems to prevent the development of PSE pork when injected into carcasses of halothane-sensitive pigs.

Evaluation of electronic technology to assess lamb carcass composition.

Accurate price signals are essential for producers of American lamb to ensure production of uniformly lean animals. Development of carcass merit-pricing systems will require the use of objective technology for assessing carcass composition or lean distribution. The objective of this study was to evaluate electronic technologies for accurate determination of lamb carcass composition. Lambs (n = 106) were selected as a representation of U.S. market lambs that transcended geographic location, sex, breed, carcass weight, yield grade, and production system. The independent variables used to predict lamb composition varied with the technology. The electronic technologies tested included realtime ultrasound, optical reflectance probe, bioelectrical impedance analysis, and electromagnetic scanning (TOBEC). All technologies, except realtime ultrasound, were tested on warm (prerigor) carcasses and repeated after a 24-h chill. Longitudinal ultrasonic scans of fat and muscle tissue depth and grading probe fat depths were marginal predictors of proportional carcass yield. The TOBEC measurements often accounted for more variability associated with kilograms of dissected lean and percentage of carcass lean than did carcass weight. Equations from TOBEC measurements were the most accurate predictors of weight and percentage of dissected and fat-free lean. Bioelectrical impedance measurements of resistance and reactance combined with carcass weight were also good predictors of carcass composition. Prediction of carcass lean distribution by measures of TOBEC were the most accurate for prediction of leg lean. The implications of usefulness of these technologies will depend on the commitment of the U. S. sheep industry in development of a lamb price discovery system based on carcass composition.

Muscle protein changes post mortem in relation to pork quality traits.

The relationship between post-mortem traits of muscle proteins and water loss traits was investigated using 84 pork loins representing the four quality traits of PSE, RSE (reddishpink, soft, exudative), RFN (reddish-pink, firm, non-exudative) and DFD. Protein solubility measurements (sarcoplasmic, myofibrillar and total) were lower and myosin denaturation (quantified by myofibrillar ATPase activity) was higher for PSE samples compared with samples from the other quality classes. RSE samples were similar to RFN samples in protein solubility and myosin denaturation, although RSE had lower values then DFD samples for protein solubility measurements. RFN samples had lower drip, thaw, cook and total water loss than RSE samples and all water loss traits were lowest for DFD samples and highest for PSE samples. Insoluble phosphorylase was the only characteristic that differentiated among PSE, RSE and RFN samples. SDS-PAGE and Western blots indicated that in PSE and RSE samples, the myofibrillar protein titin was less degraded and nebulin was more degraded compared with RFN and DFD samples. SDS-PAGE of extracted and unextracted myofibrils showed that the reduced myofibrillar solubility of PSE samples was caused by decreased extractability of the myosin heavy chain in these samples. In conclusion, although RSE samples have unacceptably high water loss, muscle protein denaturation was minimal and did not explain the low water-holding capacity.

Assessment of lamb carcass composition from live animal measurement of bioelectrical impedance or ultrasonic tissue depths.

Market weight lambs, average weight 52.5 kg (+/-6.1), were used to evaluate nontraditional live animal measurements as predictors of carcass composition. The sample population (n = 106) represented U.S. market lambs and transcended geographic location, breed, carcass weight, yield grade, and production system. Realtime ultrasonic (RU) measurements and bioelectrical impedance analysis (BIA) were used for development and evaluation of prediction equations for % boneless, closely trimmed primal cuts (BCTPC), weight or % of dissected lean tissue (TDL), and chemically derived weight or % fat-free lean (FFL). Longitudinal ultrasonic images were obtained parallel to the longissimus thoracis et lumborum (LTL), positioning the last costae in the center of the transducer head. Images were saved and fat and LTL depths were derived from printed images of the ultrasonic scans. Bioelectrical impedance analysis was administered via a four-terminal impedance plethysmograph operating at 800 microA at 50 kHz. Impedance measurements of whole-body resistance and reactance were recorded. Prediction equations including common linear measurements of live weight, heart girth, hindsaddle length, and shoulder height were also evaluated. All measurements were taken just before slaughter. Bioelectrical impedance measurements (as compared to RU and linear measurements) provided equations for %BCTPC, TDL, %TDL, FFL and %FFL with the highest R2 and lowest root mean square error. Even though BIA provided the best equations of the three methodologies tested, prediction of proportional yield (%BCTPC, %TDL, and %FFL) was marginal (R2 = .296, .551, and .551, respectively). Equations combining BIA, RU, and linear measurements greatly improved equations for prediction of proportional lean yield.

Measuring water-holding capacity in pork musculature with a tensiometer.

The water-holding capacity (WHC) of post-mortem porcine musculature is an important quality trait, and it is desirable for the industry to assess its variations ,for purposes of evaluating and processing pork products. There are several procedures to accurately determine WHC, but most are either too slow, too expensive or are impractical for commercial application. Since WHC is also important when examining the characteristics of soil, scientists routinely use an instrument called a tensiometer for this measurement. Therefore, we explored the potential application of this technique for assessing WHC in post-rigor pork muscle. The cost, potential speed and invasive application of the tensiometer in muscle were attractive characteristics. A sample (29) of pork loins, representing considerable variation in WHC were used to test the applicability of a commercial tensiometer. When tensiometer measurements were compared to 48 h drip loss, the results indicated the tensiometer could accurately detect the variations in free fluids expressed in muscle and that the procedure could be applied quickly and invasively without altering the commercial value of the product. However, particles (primarily protein and fat) in the muscle fluid became imbedded in the pores of the tensiometer ceramic tip, thus impairing the repeated use of the instrument. A plastic filter was developed to prevent clogging, but it could not be molded adequately to permit rapid insertion and removal for on-line measurements of WHC. Therefore, despite the various desirable features of the tensiometer, it failed to meet some requirements considered essential for further testing as a potential commercial, on-line procedure. First, the clogging problem must be resolved The study also indicated that the filter paper test would be more appropriate than the tensiometer for use in field tests to predict WHC when limited numbers of samples were to be tested.

Electromagnetic scanning to predict lamb carcass composition.

The electromagnetic scanner generates a constant, low-level electromagnetic field (2.5 MHz) within a large plexiglass tube. The amount of electromagnetic (EM) energy transferred (to the carcass) is highly related to lean tissue. A plot of the absorption units over distance can be used to assess the total mass of lean tissue and of the respective primal cuts. The difference in curve height between two points (D), peak phase absorption, and linear carcass measurements (pre-rigor, HCWT or post-rigor, CWT carcass weight, and carcass length, LENG) were used to predict total dissected lean (TOTLEAN), dissected leg lean (LEGLEAN), and percentage of dissected carcass lean (PERLEAN). Twenty-one pre-rigor and 22 post-rigor (24 h chill) lamb carcasses, average weight 26.8 (+/- 4.2 kg) and 26.4 (+/- 4.1 kg) kg, respectively, were evaluated from measurements of total body electrical conductivity (TOBEC). Two geometric orientations were tested for statistical accuracy in this study: A) each carcass entered the EM tunnel rear leg first, on its left lateral side, neck facing the right side of the tunnel; and B) each carcass entered the EM tunnel rear leg first, breast down, and neck up. Orientation A proved more statistically efficient for pre-rigor carcasses, and orientation B was more desirable for post-rigor carcasses. Multiple-regression models involving HCWT, LENG, and a single D measure accounted for 98.0 and 95.0%, respectively, of the total variation in pre-rigor carcass TOTLEAN and LEGLEAN in A.(ABSTRACT TRUNCATED AT 250 WORDS)

Is colour brightness (L-value) a reliable indicator of water-holding capacity in porcine muscle?

A total of 265 pork carcasses representing a broad variation in quality was used to examine the relationship between colour (L-value) and water-holding capacity (WHC) in the longissimus thoracis et lumborum. Thirty-four samples appeared to possess 'normal' reddish pink colour (L-value 52·0-58·0) but had 'unacceptable' WHC (>5·0% drip loss). Conversely, 25 samples were pale in colour (L-value >58·0) but were 'acceptable' in WHC. When muscles were dark (L-value 52·0) the WHC was always acceptable. Some samples were subjected to further analysis. Variations in iron content, haematin content, sarcomere length and degree of soluble protein denaturation failed to explain why brightness and WHC were not more closely related. When L-value and WHC were compared to pH(45) (pH, 45 min post mortem), WHC exhibited a biphasic relationship to pH(45) whereas L-value did not. These results indicate that WHC and brightness are determined by independent pre-rigor biological phenomena, strengthening the argument that brightness is not necessarily a reliable predictor of WHC. Researchers selecting pork for specific investigations, or commercial companies using fresh pork for either further processing or for retail, should not rely on colour brightness alone to insure that other quality properties such as WHC and firmness will also be acceptable.

Pelvic growth, calf birth weight and dystocia in Holstein x Hereford heifers.

The pelvic area was measured in 129 Holstein x Hereford heifers at 10, 16 and 22 months of age. The heifers were fed an all forage diet. Pelvic growth was not linear over time, changing from an increase of 0.27 +/- 0.2 cm(2)/day during the first 6 months of the study to 0.13 +/- 0.13 cm(2)/day during the last 6 months (P<0.01). The relationship of pelvic area to body weight, height at hooks, and distance from hooks to pins did not change with age, and a moderate correlation between the pelvic area and these other measures (R=0.20 to 0.80) was noted. The pelvic area was measured within 24 hours after calving in 76 of the heifers. The rate of increase of pelvic area/day increased significantly (P < 0.01) in the month prior to calving from 0.14+/-0.13 cm(2) to 1.15 +/- 0.88 cm(2). As a result, the pelvic area at calving had a moderate correlation (R=0.29 to 0.52) to the pelvic area prior to calving. Logistic regression and discriminant analysis techniques were used to model the influence of the pelvic area and calf birth weight on the incidence of dystocia. Ratio of the pelvic area at calving to calf birth weight significantly (P < 0.01) influenced the incidence of dystocia. Logistic regression techniques were not superior to discriminant analysis; both correctly predicted 73% of the cases. Pelvic area measurement at any time other than calving was not associated with dystocia (P >0.05). Pelvic area and calf birth weight are important determinants of dystocia in heifers. The high degree of variation noted in pelvic growth, in particular during the month prior to calving, resulted in low correlation between pelvic area at calving and the precalving measurement. Therefore, we were not able to predict dystocia by measuring the pelvic area prior to calving.

Quality attributes of major porcine muscles: A comparison with the Longissimus Lumborum.

Quality attributes of the longissimus lumborum (LL) were compared to the attributes of the muscles semimembranosus (SM), rectus femoris (RF), biceps femoris (BF), gluteus medius (GM) and the lateral portion of the semitendinosus (ST) in the ham, the psoas major (PM) in the loin and the supraspinatus (SS), infraspinatus (IS) and triceps brachii (TB) in the shoulder. Carcasses were allocated to quality groups based on measurements of muscle exudate and lightness (CIE-L(∗)) in the LL. The SM, BF, GM and ST in the ham were similar to the LL (P > 0·05) in meat ultimate pH (pHu) and exudate and the GM, ST and LL were similar (P > 0·05) to the LL in lightness. The TB, RF, SS, PM and IS were similar (P > 0·05) in exudate, lightness and pHu and compared to the LL, were less exudative (P < 0·05) and darker (P < 0·05). When the LL was classed pale, and exudative, the GM, BF, SM and ST were also pale and exudative but the other muscles were darker and non-exudative. When the LL was classed dark and non-exudative, all other muscles were dark, non-exudative and the pHu was high. Therefore, the LL could serve as a reliable indicator of colour and exudate for all porcine musculature when the condition was dark and non-exudative (i.e. DFD). However, when the condition was pale and exudative (i.e. PSE), then the LL would serve as a reliable indicator only for the four major ham muscles, excluding the RF.

The effectiveness of examining early post-mortem musculature to predict ultimate pork quality.

Variations in pork quality reflect value differentials. However, only when they can be easily, accurately, rapidly and cost-effectively detected, can swine producers expect to eliminate poor quality from their herds through genetic selection, and can the industry be expected to take the necessary environmental precautions to prevent poor quality. This study was designed to assess the effectiveness of various techniques thought to predict ultimate pork quality through the examination of the physical and chemical properties of early post-mortem (PM) musculature. Based on stiffness and pH 30, 285 carcasses were selected. This selection procedure ensured a wide variation in ultimate quality. Using 12 instruments simultaneously, temperature, stiffness, electrical properties, lightness properties, and pH 45 of the early PM longissimus thoracis et lumborum were recorded to predict ultimate quality. Based on post-rigor light reflection and water-holding capacity (WHC), quality was assigned to one of five arbitrary groups. Of all techniques tested, the only one with any potential for adequate prediction of quality categories was pH 45. Combination of different techniques did not significantly increase predictive values. For predicting quality of single carcasses, pH 45 should not be considered satisfactory. However, based on our success in selecting carcasses representing quality variation for this study and the results obtained from the study, using pH 45 and muscle stiffness to select groups of carcasses is feasible. We conclude that the techniques used early post mortem are not appropriate for predicting ultimate pork quality for single carcasses. At present we recommend that only post-rigor muscle be considered, and that ultimate pH, light reflection and a measure of WHC should be used.