Influence of packaging method and storage time on shear value and mechanical strength of intramuscular connective tissue of chevon

The objectives of this study were to determine the effects of storage time (ST) and packaging method (PM) on tenderness and changes in intramuscular connective tissue (IMCT) strength of chevon. Spanish does (8 mo of age, average BW 25 kg) were harvested (n = 12), chilled at 4 degrees C for 24 h, and then fabricated into 2.5-cm-thick leg, shoulder/arm, and loin/rib cuts. The cuts from six carcasses were vacuum-packed and aged at 2 degrees C for 0, 4, 8, or 12 d. To assess the influence of a packaging method that favors oxidation on postmortem tenderization, the cuts from the remaining six carcasses were placed on styrofoam trays, overwrapped with polyvinyl-chloride film, and stored at 2 degrees C for similar periods. At each ST, longissimus (LM), semimembranosus (SM), and triceps brachii (TB) muscles were assessed for Warner-Bratzler shear (WBS) values. The WBS of uncooked meat, myofibrillar fragmentation index (MFI), and collagen solubility were assessed on LM. The IMCT samples were prepared to assess changes in mechanical strengths and for scanning electron microscopy (SEM). Intact honeycomb structures of endomysium, with no muscle fiber elements, were observable under SEM. The PM or ST did not influence the mechanical strength of IMCT preparations, as measured by a texture analyzer. Collagen solubility of LM muscles also did not change during aging. For both PM, cooked meat WBS values were higher (P < 0.01) in SM and TB than in LM. In the SM samples, the average WBS values were higher (P < 0.01) at d 0 than at other ST. Although MFI of LM increased with increasing aging time (P < 0.05), changes in WBS over ST were minimal in TB and LM samples. The WBS of uncooked LM decreased sharply up to 8 d postmortem in both PM (P < 0.05). However, there was no PM x ST interaction to indicate any adverse influence of packaging on tenderization of chevon. The results suggest that aging chevon cuts for more than 4 d may not result in significant additional improvement in tenderness.     

Effect of the callipyge gene on muscle growth, calpastatin activity, and tenderness of three muscles across the growth curve

Changes in muscle growth, calpastatin activity, and tenderness of three muscles were assessed in 20 callipyge and 20 normal wether lambs slaughtered at live weights (LW) of 7, 20, 36, 52, and 69 kg. At 24 h postmortem, the longissimus (LM), semimembranosus (SM), and supraspinatus (SS) muscles were removed and weighed and samples were obtained for calpastatin activity (CA; 24 h) and Warner-Bratzler shear force (WBS; aged 6 d). For muscle weights and calpastatin activity, the weight group x muscle x phenotype interaction was significant (P < 0.05). Muscle weights were similar (P > 0.05) between phenotypes for all three muscles at 7 kg LW. At 20 kg LW, the LM and SM muscles from the callipyge lambs were heavier (P < 0.05) than those from normal lambs; however, the SS did not differ (P > 0.05) between phenotypes at 7, 20, or 52 kg. From 20 to 69 kg LW, the LM and SM weights were 42 and 49% heavier (P < 0.05) for callipyge than for normal lambs. Calpastatin activity of the callipyge LM was greater (P < 0.05) than that of normal LM at 36, 52, and 69 kg. In the callipyge LM, CA was similar (P > 0.05) at 20, 36, and 52 kg LW and did not differ (P > 0.05) from 7-kg or 69-kg values. Calpastatin activity declined (P < 0.05) across the growth curve for the SM and SS, but values were higher (P < 0.05) in the SM in callipyge than in normal lambs. Shear force values of the LM were lower (P < 0.05) for normal lambs at 36, 52, and 69 kg LW than for callipyge lambs. In the SM and SS, WBS values decreased (P < 0.05) across the growth curve, but values were higher (P < 0.05) for callipyge lambs in the SM only. These data indicate that the selective muscular hypertrophy of the callipyge phenotype develops during the postnatal growth period between 7 and 20 kg LW (19 and 100 d of age). Longissimus and semimembranosus muscles in the callipyge lambs were over 40% heavier from 20 to 69 kg LW; however, they also had higher levels of calpastatin activity and Warner-Bratzler shear force during this time period, indicating the need for postmortem tenderization treatments to improve palatability.     

Characterization and consumer acceptance of three muscles from Hampshire x Rambouillet cross sheep expressing the callipyge phenotype

Eight Hampshire x Rambouillet crossbred wethers expressing the callipyge phenotype and eight Hampshire x Rambouillet half-sibling wethers with a normal phenotype were slaughtered when they reached 59 kg. The supraspinatus (SPM), longissimus (LM), and semitendinosus (STM) muscles were analyzed to determine callipyge effects on calpain and calpastatin activities, sarcomere length, percentage of muscle fiber types, and muscle fiber areas. After 14 d of aging, chops were frozen until analyses for trained sensory panel evaluations, Warner-Bratzler shear force values, and consumer perceptions of tenderness, flavor, juiciness, and overall satisfaction of chops were conducted. Calpastatin activity was 57% greater (P < 0.05) and m-calpain activity was 33% greater (P < 0.05) in muscles from carcasses of callipyge than normal sheep. Sarcomeres were shorter (P < 0.001) in the LM than the SPM or STM, regardless of phenotype. Muscle fiber area was 76% larger (P < 0.05) in the LM of callipyge than normal sheep, but muscle fiber area was not affected (P > 0.05) by phenotype in the SPM or STM. Phenotype had no effect (P = 0.12) on the percentage of slow-twitch, oxidative fiber types in any of the three muscles. In STM and LM from callipyge lambs, the percentage of fast-twitch, oxidative/glycolytic fibers was lower (P < 0.05) and that of fast-twitch-glycolytic fibers was higher (P < 0.05) than in their normal counterparts. Phenotype did not affect (P = 0.90) the fiber type percentage in the SPM. Callipyge LM were less tender and normal LM were more tender than other chops (P < 0.05). Callipyge loin chops had higher Warner-Bratzler shear force values than other chops (P < 0.001). Consumers rated fewer (P < 0.05) callipyge loin and shoulder chops acceptable in juiciness, tenderness, and overall acceptability than normal chops, but phenotype did not affect (P > 0.05) consumer acceptability of leg chops. These results indicate that LM from Hampshire x Rambouillet sheep displaying the callipyge phenotype had higher calpastatin activity and were less tender than the LM from normal sheep. In addition, consumer perceptions indicated that only one in 10 leg chops, one in five shoulder chops, and one in four loin chops from callipyge sheep were unacceptable.     

Variation in palatability and biochemical traits within and among eleven beef muscles

The objective of this study was to determine the extent of variation in, and relationships among, biochemical and palatability traits within and among 11 major beef muscles. Longissimus thoracis et lumborum (LD), psoas major (PM), gluteus medius (GM), semimembranosus (SM), adductor (AD), biceps femoris (BF), semitendinosus (ST), rectus femoris (RF), triceps brachii (TB), infraspinatus (IS), and supraspinatus (SS) from one side of 31 Charolais x MARC III steer carcasses were vacuum-packaged, stored at 2 degrees C until 14 d postmortem, and then frozen at -30 degrees C. The 2.54-cm-thick steaks were obtained from two or three locations within muscles in order to assess biochemical traits and Warner-Bratzler shear force, and from near the center for sensory trait evaluation. The PM was most tender and was followed by IS in both shear force and tenderness rating (P < 0.05). The other muscles were not ranked the same by shear force and tenderness rating. The BF had the lowest (P < 0.05) tenderness rating. The PM, GM, and LD had lower (P < 0.05) collagen concentration (2.7 to 4.5 mg/g muscle) than muscles from the chuck and round (5.9 to 9.0 mg/g), except for the AD (4.9 mg/g). Desmin proteolysis was highest (P < 0.05) for BF and LD (60.7 and 60.1% degraded), and was lowest (P < 0.05) for PM (20.2%). The PM, TB, IS, RF, and ST had relatively long sarcomere lengths (> 2.1 microm), whereas the GM had the shortest (P < 0.05) sarcomere length (1.7 microm). Cooking loss was lowest (P < 0.05) for BF (18.7%) and was followed by LD and IS (20.7%); it was highest (P < 0.05) for ST (27.4%). Across all muscles, tenderness rating was highly correlated (r > 0.60) with shear force, connective tissue rating, sarcomere length, and collagen content. Within a muscle, correlations among all traits were generally highest in LD and lowest in AD. Within muscle, location effects were detected (P < 0.05) for shear force (PM, ST, BF, SM, and RF), sarcomere length (PM, ST, BF, LD, SS, IS, SM, and RF), collagen concentration (PM, BF, SS, IS, SM. AD, TB, and RF), desmin degradation (PM, GM, BF, SM, AD, and, RF), and cooking loss (all muscles except SS and AD). There is a large amount of variation within and among muscles for tenderness traits and tenderness-related biochemical traits. These results increase our understanding of the sources of variation in tenderness in different muscles and provide a basis for the development of muscle-specific strategies for improving the quality and value of muscles.     

Relationship between marbling group and major muscle contribution to beef carcass mass

Left sides from 18 beef carcasses (9 steers and 9 heifers) were divided equally among three marbling groups (low = traces or slight; intermediate = small or modest; high = slightly abundant) and evaluated to determine the relationship between longissimus composition and the percentage each major muscle contributes to the weight of the beef carcass. The adductor (A), biceps femoris (BF), deep pectoral (DP), gluteal group (GL), infraspinatus (I), longissimus (L), psoas major (PM), rectus abdominis (RA), rectus femoris (RF), semimembranosus (SM), semitendinosus (ST), serratus ventralis (SV), spinalis (SP), supraspinatus (SU) and triceps brachii (TB) were removed, trimmed of external fat and weighed. Muscle weights were expressed as a percentage of hot carcass weight: A = .76%; BF = 3.30%; DP = 1.89%; GL = 1.81%; I = 1.10%; L = 3.35%; PM = .95%; RA = 1.12%; RF = .94%; SM = 2.35%; ST = 1.14%; SV = 2.26%; SP = .82%; SU = .69% and TB = 1.83%. The deep pectoral and triceps brachii were heavier (P less than .05) in steer carcasses than in heifer carcasses. No other significant sex effects were noted. Percentage of muscle tended to decrease with increasing marbling level; however, the linear regression of relative muscle weight on marbling level was significant for the BF, DP, PM, SM, SU and TB. Using marbling score or yield grade factors to predict the percentage of individual muscles in the carcass resulted in R/ values greater than .4 in 7 of the 15 muscles evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of implanting ram and wether lambs with zeranol at birth and weaning on palatability and muscle collagen characteristics.

Thirty-five zeranol-implanted (I) and nonimplanted (NI) ram and wether lambs representing four treatments (implanted rams [IR], nonimplanted rams [NIR], implanted wethers [IW], and nonimplanted wethers [NIW]) were evaluated for meat palatability and muscle collagen characteristics. Rib (longissimus muscle, LM) chops from I lambs were juicier (P less than .05) than rib chops from NI lambs. Chops from IR lambs had more (P less than .05) detectable connective tissue and lower myofibrillar and overall tenderness scores than chops from NIR, IW, or NIW lambs. Warner-Bratzler shear (WBS) values tended to be higher (P = .06) for LM chops from rams than for those from wethers, but WBS values for Biceps femoris (BF) chops were similar (P greater than .05) for rams and wethers. Implanting did not affect (P greater than .05) WBS values. Rams had more (P less than .05) LM heat-labile (soluble, SC), nonheat-labile (insoluble, IC), and total collagen (TC) and a higher (P less than .05) percentage of SC (SC/TC) than did wethers. Soluble collagen, TC, and percentage of SC for the BF were higher (P less than .05) and IC tended (P = .09) to be higher in chops from rams than in those from wethers. Implanting did not affect (P greater than .05) collagen amount or solubility. Serum nonprotein hydroxyproline (NPHP) was higher (P less than .05) in rams than in wethers throughout the feeding period and tended (P = .05) to be higher at slaughter. Implanting did not affect (P greater than .05) serum NPHP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Early postmortem biochemical factors influence tenderness and water-holding capacity of three porcine muscles

The objective of this study was to determine whether differences in pork tenderness and water-holding capacity could be explained by factors influencing calpain activity and proteolysis. Halothane-negative (HAL-1843 normal) Duroc pigs (n = 16) were slaughtered, and temperature and pH of the longissimus dorsi (LD), semimembranosus (SM), and psoas major (PM) were measured at 30 and 45 min and 1, 6, 12, and 24 h postmortem. Calpastatin activity; mu-calpain activity; and autolysis and proteolysis of titin, nebulin, desmin, and troponin-T were determined on muscle samples from the LD, SM, and PM at early times postmortem. Myofibrils from each muscle were purified to assess myofibril-bound (mu-calpain. Percentage drip loss was determined, and Warner-Bratzler shear (WBS) force was analyzed. Myosin heavy-chain (MHC) isoforms were examined using SDS-PAGE. The pH of PM was lower (P < 0.01) than the pH of LD and SM at 30 and 45 min and 1 h postmortem. The PM had a higher (P < 0.01) percentage of the MHC type IIa/IIx isoforms than the LD. The-LD had the greatest proportion of (P < 0.01) MHC IIb isoforms of any of the muscles. The PM had the lowest (P < 0.01) percentage of MHC IIb isoforms and a greater (P < 0.05) percentage of type I MHC isoforms than the LD and SM. The PM had less (P < 0.01) drip loss after 96 h of storage than the SM and LD. The PM had more desmin degradation (P < 0.01) than the LD and SM at 45 min and 6 h postmortem. Degradation of titin occurred earlier in the PM than the LD and SM. At 45 min postmortem, the PM consistently had some autolysis of mu-calpain, whereas the LD and SM did not. At 6 h postmortem, some autolysis of mu-calpain (80-kDa subunit) was observed in all three muscles. The rapid pH decline and increased rate of autolysis in the PM paralleled an earlier appearance of myofibril-bound mu-calpain. The SM had higher calpastatin activity (P < 0.05) at 45 min, 6 h, and 24 h and had higher WBS values at 48 h (P < 0.01) and 120 h (P < 0.05) postmortem than the LD. At 48 and 120 h postmortem, more degradation of desmin, titin, and nebulin were observed in the LD than in the SM. These results show that mu-calpain activity, mu-calpain autolysis, and protein degradation are associated with differences in pork tenderness and water-holding capacity observed in different muscles.     

Relationship between longissimus composition and the composition of other major muscles of the beef carcass

Left sides from 18 beef carcasses (9 steers and 9 heifers), selected to represent a wide range of marbling scores, were evaluated to determine the relationship between longissimus composition and the composition of other major muscles. The adductor (A), biceps femoris (BF), deep pectoral (DP) gluteal group (GL), infraspinatus (I), longissimus (L), psoas major (PM), rectus abdominis (RA), rectus femoris (RF), semimembranosus (SM), semitendinosus (ST), serratus ventralis (SV), spinalis (SP), supraspinatus (SU) and triceps brachii (TB) were removed, trimmed of external fat, weighed and ground for proximate analysis. Fat content of all muscles was related linearly (P less than .001) to L fat content (R2 values ranged from .67 to .84). The ST had the lowest mean fat content (4.4%) and SP had the highest mean percentage of fat (16.1%). The L ranged from 3.59% to 15.42% fat with a mean of 8.61%. Longissimus fat percentage can be used to predict the fat content of the other major muscles of the beef carcass.     

云岭牛不同解剖部位肉品质评价

为了明确云岭牛不同解剖部位肉的品质特性,本试验测定了云岭牛冈上肌（SU）、冈下肌（IF）、臀三头肌（TB）、菱形肌（RH）、颈腹侧锯肌（SVC）、夹肌（SP）,中部胴体的腰大肌（PM）、背最长肌（LD）、背阔肌（LA）,后部胴体的半膜肌（SM）、半腱肌（ST）、股二头肌（BF）、臀中肌（GM）、股直肌（RF）、股外侧肌（VL）和阔筋膜张肌（TFL）共16个解剖部位肉的压力失水率、蒸煮损失、剪切力、pH、亮度（L^*）、红度（a^*）、黄度（b^*）、粗蛋白质、脂肪、水分10项品质指标,并通过方差分析、相关性分析和标准化分析研究其品质特性。结果显示,云岭牛不同解剖部位肉之间的10项品质指标均存在显著差异（P<0.05）。冈上肌、冈下肌、腰大肌、颈腹侧锯肌和阔筋膜张肌的嫩度较好,其剪切力均低于4 kg。夹肌、半腱肌和股外侧肌的保水性较差,半腱肌的L^*值最高。相关性分析结果表明,剪切力和压力失水率、蒸煮损失呈显著正相关。标准化分析发现,背最长肌和半腱肌具有相似的品质特征;股二头肌、臀中肌和股外侧肌具有相似的品质特征。结果表明,部位因素对云岭牛肉品质具有显著影响,云岭牛胴体前部肉品质较好,可以作为开发高档产品的原料来源。     

Effects of a unique application of electrical stimulation on tenderness, color, and quality attributes of the beef longissimus muscle

This study evaluated effects of four uniquely applied beef carcass electrical stimulation (ES) treatments on USDA grade factors, muscle color, subprimal purge loss, cooked steak weight loss, and cooked steak tenderness. One side of each (n = 284) beef carcass was subjected to ES using one of four treatments (medium voltage for medium duration, MVMD; medium voltage for long duration, MVLD; high voltage for medium duration, HVMD; or high voltage for long duration, HVLD) and was compared to its corresponding non-ES control side. Electrical stimulation of beef sides was applied focusing on middle meats while preventing severe contraction of the round and chuck. From matched (ES and control) sides of 120 carcasses (10 each of Select, low Choice, and upper two-thirds of Choice in each of the four ES treatments), longissimus steaks (2.5 cm thick) were cooked and used for Warner-Bratzler shear force (WBS) analysis. Mean marbling scores (n = 284) for stimulated sides did not differ (P = .923) from those for control sides within ES treatment classes. Mean values for CIE L*, a*, and b* of lean color (n = 284) were higher (P < .05) for MVMD, MVLD, HVMD, and HVLD treated sides than for the respective control sides. When WBS values for steaks were adjusted to an equal visual degree of doneness, WBS values (n = 120) were lower (P < .05) for ES treated sides than for control sides for all four types of ES application treatments. Treatment responses were not influenced by USDA Quality Grade group. For those carcasses for which the control sides had WBS values greater than 4.5 kg, matching sides treated with MVMD, MVLD, HVMD, or HVLD had WBS values less than 4.5 kg 50, 88, 60, and 75% of the time, respectively. Mean cooked steak weight loss (n = 120), adjusted to an equal visual degree of doneness, and mean purge loss (n = 24) did not differ with ES treatment.     

Influence of harvest processes on pork loin and ham quality

The purpose of this study was to determine the specific effects of extending the interval between dwell time and the duration of scalding on pork quality attributes. Sixty-four Duroc x Yorkshire pigs were randomly assigned to a 2 x 2 factorial treatment arrangement. Treatments included extending the dwell duration from 5 to 10 min and extending the scald duration from 5 to 8 min. All carcasses entered the cooler 50 min after exsanguination. At exsanguination, blood was collected for three 1-min intervals and then for a final 2-min period. Temperature and pH of the LM and semimembranosus muscle (SM) were measured at 45 min, and at 2, 4, 6, and 24 h postmortem (PM). Hunter L*, a*, and b* values were determined on the LM, SM, and biceps femoris (BF). Purge loss was measured on the SM, BF, and the sirloin end of the loin. Drip loss was measured in duplicate from LM chops after 1 and 5 d of storage. Warner-Bratzler shear force (WBS) measurements were determined on LM chops aged 1, 3, 5, and 7 d PM. Over 99% of the collected blood was obtained during the first 3 min after sticking. Carcasses scalded for 8 min had greater (P < 0.05) semi-membranosus 2 h temperature (28.8 degrees C) than carcasses scalded 5 min (27.3 degrees C). An 8-min scald process resulted in longissimus dorsi chops with lower hue angle and greater WBS values than the 5-min scald process. Increasing dwell time from 5 to 10 min resulted in biceps femoris chops with greater hue angle and loin chops with greater WBS values at 3 d PM. Harvest processes did not significantly affect subjective quality scores, Hunter L* values, purge or drip loss. Lengthening the duration of dwell and scalding may result in a more rapid PM pH decline. Reducing the duration of scalding may lead to increased time for manual removal of hair. Because of differences in facilities, it is recommended that individual facilities monitor dwell and scald durations to determine how to best minimize time of entry into the cooler.     

Postmortem proteolysis and calpain/calpastatin activity in callipyge and normal lamb biceps femoris during extended postmortem storage.

The present experiment was conducted to determine whether calpastatin inhibits only the rate, or both the rate and extent, of calpain-induced postmortem proteolysis. Biceps femoris from normal (n = 6) and callipyge (n = 6) lamb was stored for 56 d at 4 degrees C. Calpastatin activity was higher (P < .05) in the callipyge muscle at 0 and 14 d postmortem, but not at 56 d postmortem. The activity of mu-calpain did not differ between normal and callipyge biceps femoris at 0 and 56 d postmortem (P > .05), but was higher at 14 d postmortem in the callipyge muscle (P < 0.05). The activity of m-calpain was higher in the callipyge muscle (P < 0.05). Western blot analyses of titin, nebulin, dystrophin, myosin heavy chain, vinculin, alpha-actinin, desmin, and troponin-T indicated that postmortem proteolysis was less extensive in callipyge than in normal biceps femoris at all postmortem times. The results of this experiment indicate that calpastatin inhibits both the rate and extent of postmortem proteolysis.     

Mapping intramuscular tenderness variation in four major muscles of the beef round

The objective of this study was to quantify intramuscular tenderness variation within four muscles from the beef round: biceps femoris (BF), semitendinosus (ST), semimembranosus (SM), and adductor (AD). At 48 h postmortem, the BF, ST, SM, and AD were dissected from either the left or right side of ten carcasses, vacuum packaged, and aged for an additional 8 d. Each muscle was then frozen and cut into 2.54-cm-thick steaks perpendicular to the long axis of the muscle. Steaks were broiled on electric broilers to an internal temperature of 71 degrees C. Location-specific cores were obtained from each cooked steak, and Warner-Bratzler shear force was evaluated. Definable intramuscular shear force variation (SD = 0.56 kg) was almost twice as large as between-animal shear force variation (SD = 0.29 kg) and 2.8 times as large as between-muscle variation (SD = 0.20 kg). The ranking of muscles from greatest to least definable intramuscular shear force variation was BF, SM, ST, and AD (SD = 1.09, 0.72, 0.29, and 0.15 kg, respectively). The BF had its lowest shear force values at the origin (sirloin end), intermediate shear force values at the insertion, and its highest shear force values in a middle region 7 to 10 cm posterior to the sirloin-round break point (P < 0.05). The BF had lower shear force values toward the ST side than toward the vastus lateralis side (P < 0.05). The ST had its lowest shear force values in a 10-cm region in the middle, and its highest shear force values toward each end (P < 0.05). The SM had its lowest shear force values in the first 10-cm from the ischial end (origin), and its highest shear force values in a 13-cm region at the insertion end (P < 0.05). Generally, shear force was lower toward the superficial (medial) side than toward the deep side of the SM (P < 0.05). There were no intramuscular differences in shear force values within the AD (P > 0.05). These data indicate that definable intramuscular tenderness variation is substantial and could be used to develop alternative fabrication and(or) merchandising methods for beef round muscles.     

Environmental effects on pig performance, meat quality, and muscle characteristics

The objective of this experiment was to determine the effect of diverse production systems on pig performance, muscle characteristics, and their relation to pork quality measures. Birth and rearing conditions were evaluated using 48 barrows during the fall/winter months. Pigs were farrowed in either indoor crates or outdoor huts. At weaning, indoor- and outdoor-born pigs were allotted randomly to treatments arranged in a 2 x 2 factorial design with two birth (indoor vs. outdoor) and rearing (indoor vs. outdoor) environments. Pigs housed indoors were on concrete-slatted flooring (1.2 m2/pig), and pigs housed outdoors were on an alfalfa pasture (212 m2/pig). Body weight data were collected. Muscle samples were removed within 1 h postmortem from the longissimus (LM) and semimembranosus (SM) muscles. Muscle samples were stained histochemically to identify type I, IIA, and IIB/X muscle fibers. Boneless loins were collected from the left side of each carcass and aged for 14 d. Objective and subjective color measurements were taken on the longissimus muscle at the 10th rib on d 14 postmortem. Loin chops were evaluated for sensory attributes, shear force, and retail display features. Pigs born outdoors were heavier and had a greater ADG at most growth intervals postweaning (d 28, 56, and 112; P < 0.05) than pigs born indoors. Pigs reared outdoors were heavier (P = 0.02) at d 140 (120.1 vs. 112.9 +/- 4.9 kg), and had higher (P = 0.01) ADG (2.2 vs. 1.9 kg/d) and gain:feed ratios (0.41 vs. 0.37) than did pigs reared indoors. Birth x rearing environment interactions were not significant (P > 0.10) for most measures. Carcass and meat quality measures did not differ (P > 0.05) among treatment groups, but loin chops from outdoor born or reared pigs had higher (P < 0.05) a* values than chops from pigs born or reared indoors. The LM muscle of pigs born outdoors had a higher (P < 0.01) percentage of type I, and a lower (P < 0.05) percentage of type IIA fibers than did pigs born indoors. Pigs reared outdoors had a higher (P < 0.01) percentage of IIA fibers and a lower (P < 0.05) percentage of IIB/X fibers than did pigs reared indoors for the LM and SM muscles. Outdoor production systems may influence growth, pork color, and muscle fiber types.     

Protein kinetics in callipyge lambs

The objectives for this experiment were to determine the effect of the callipyge phenotype on protein kinetics. We studied callipyge and normal lambs (n = 37) at 5, 8, and 11 wk of age (n = 4 to 7/ group) to determine how protein kinetics are altered by this trait. Total protein, DNA, and RNA and calpastatin activity were measured in five skeletal muscles and in the heart, kidneys, and liver, and protein accretion rates were calculated. At 8 wk, the fractional synthesis rates of proteins in these tissues were measured in vivo using a primed, continuous 8-h infusion of [2H5]phenylalanine. Fractional rates of protein degradation were estimated by differences. At 5 wk of age, muscle weights, protein mass, protein:DNA, RNA:DNA, and calpastatin activity were higher (P < .05) for callipyge, and protein mass differences continued to increase through 11 wk. At 8 wk, fractional rates of protein synthesis and degradation were lower (P < .05) in callipyge than in normal lambs. The organs of callipyge lambs exhibited reduced growth at 11 wk. Thus, enhanced muscle growth seems to be maintained in callipyge lambs by reduced protein degradation rather than increased protein synthesis. However, we cannot exclude the possibility that the initial onset of the callipyge condition may be caused by an increase in the fractional rate of protein synthesis.     

Characterization of certified Angus beef steaks from the round, loin, and chuck

Beef carcasses (n = 150) of A-maturity were selected randomly to determine baseline shear force and sensory panel ratings, assess variation in tenderness, and evaluate mean value differences between Certified Angus Beef (CAB), commodity Choice, and Select steaks. Three steaks were removed from the triceps brachii (TB), longissimus lumborum (LL), gluteus medius (GM), semimembranosus (SM), biceps femoris (BF), and quadriceps femoris complex (QF), and assigned to Warner-Bratzler shear (WBSF) and sensory panel analyses. As anticipated, marbling score and measured percentage of i.m. fat were greatest (P < 0.05) for CAB, intermediate (P < 0.05) for Choice, and least (P < 0.05) for Select carcasses. A muscle x quality level interaction (P < 0.05) was observed for WBSF values and sensory panel tenderness ratings. The TB, LL, GM, and BF steaks from CAB carcasses had lower (P < 0.05) WBSF than Select steaks from the same muscles. Even though WBSF values did not differ (P > 0.05) between CAB and Choice QF and TB steaks, the LL and GM steaks from CAB carcasses were more tender (P < 0.05) than Choice-grade LL and GM steaks. The TB from Select carcasses had higher (P < 0.05) WBSF values than TB steaks from CAB or Choice carcasses, but sensory panel ratings indicated that quality level showed little consistency among the GM, SM, BF, and QF. Trained sensory panelists rated CAB LL steaks more tender (P < 0.05) than LL steaks from Choice and Select carcasses, and Choice LL steaks were evaluated as more (P < 0.05) tender than those from Select carcasses. These results demonstrate that the influence of marbling on tenderness was more evident in muscles of middle meats than in end cuts, particularly in muscles of the round.     

The Quality Evaluation of Different Anatomical Locations of Yunling Cattle

In order to define the quality characteristics of different anatomical locations of Yunling cattle,the pressing loss rate,cooking loss rate,shear force,pH, L^* value,a^* value,b^* value,crude protein content,crude fat content and moisture of supraspinatus (SU),infraspinatus (IF),triceps brachii (TB),rhomboideus (RH),serratus ventraliscervicis (SVC),splenius (SP),psoas major (PM),longissimus dorsi (LD),latissimus dorsi (LA),semimembranosus (SM),semitendinosus (ST),biceps femoris (BF),gluteus medius (GM),rectusfemoris (RF),vastus lateralis (VL), tensor fasciae latae (TFL) from Yunling cattle carcass were determined.The quality traits of Yunling cattle meat among different anatomical locations were analyzed using variance,correlation and standardization analysis. The result showed that there were significant differences in quality traits among various anatomical locations (P<0.05). The SU,IF,PM,SVC and TFL had higher tenderness comparing to other muscles with shear force values less than 4 kg,while the water holding capacity of SP,ST and VL was poorer than other muscles. The ST had the highest L^* value among all muscles. There was significantly positive correlation between shear force and pressing loss, cooking loss rate. The LD and ST had similar quality characteristic,while BF,GM and VL had similar quality characteristic. It was showed that different parts of muscle had significant effect on Yunling cattle meat quality.The quality of forequarter meat was better, which could be used to develop high-end products.     

Feeding high levels of vitamin D3 does not improve tenderness of callipyge lamb loin chops

The objective of this study was to determine whether feeding high doses of vitamin D3 7 d before slaughter would increase muscle Ca++ levels and result in more tender loin chops. Market lambs (n = 4 callipyge and 4 normal in Exp. 1, and n = 16 calipyge and 16 normal in Exp. 2) were randomly and equally assigned to feeding groups based on callipyge genotype and experimental diet, (vitamin D3 or control). Serum Ca++, muscle Ca++, Warner-Bratzler shear force, and troponin-T degradation data were analyzed. In Exp. 1, vitamin D3 was supplemented at 1 or 2 x 10(6) IU/d. The 2 x 10(6) IU dose resulted in the greatest serum Ca++ reponse and was chosen for Exp. 2. In Exp. 2, serum Ca++ concentration was higher (P < 0.05) for normal and callipyge lambs fed the vitamin D3 diet than for the control diet fed lambs. Muscle Ca++ concentrations, however, were not higher (P = 0.28) for the vitamin D3-fed lambs. Warner-Bratzler shear values were higher (P < 0.05) for callipyge than for normal lambs, but no differences were observed with vitamin D3 supplementation. These data were supported by results from Western blot analysis of troponin-T degradation, in which no differences were observed for vitamin D3 vs control diet lambs at 14 d postmortem. This experiment showed that feeding 2 x 10(6) IU/d of vitamin D3 to market lambs, callipyge or normal, raised serum Ca++ concentration, but did not increase muscle Ca++ concentration. This lack of response in muscle Ca++ was likely the reason that no differences were observed for Warner-Bratzler shear force values or troponin-T degradation data between the vitamin D3 and control loin chops. A higher dose of vitamin D3 may be required to improve tenderness.     

Relative contributions of animal and muscle effects to variation in beef lean color stability

Muscles from beef carcasses (n = 100) were selected from a commercial processor and aged for 14 d. Longissimus lumborum (LL), semimembranosus (SM), biceps femoris (BF), gluteus medius (GM), triceps brachii (TB), rectus femoris, vastus lateralis, adductor, semitendinosus, infraspinatus, teres major, biceps femoris ischiatic head, biceps femoris sirloin cap, and gracillus steaks were placed in display for 9 d. Instrumental color variables [lightness (L*), redness (a*), yellowness (b*), hue angle, chroma, and overall color change from d 0 (E)] were determined on d 0, 1, 3, 6, and 9 of display. Muscle pH and myoglobin content were determined for LL, SM, BF, GM, and TB. Muscles differed (P < 0.05) in initial values of each color variable evaluated, and the extent and timing of changes during display differed across muscles. Relationships between color variables measured in LL steaks and those measured in steaks from other muscles differed across days of display with the strongest relationships being observed earlier in the display period for labile muscles and later in stable muscles. Lightness of LL steaks was correlated with lightness of all of other muscles evaluated, regardless of display day (r = 0.27 to 0.79). For a*, hue angle, chroma, and E values, the strongest relationships between LL values and those of other muscles were detected between d 9 LL values and those of other muscles on d 3, 6, or 9, depending on the relative stability of the muscle. Correlation coefficients between d 9 a*, hue angle, chroma, and E values in LL and those of other muscles were 0.50, 0.65, 0.28, and 0.43 (P < 0.05) or greater, respectively, for the muscles included in the study. Myoglobin content of SM, BF, GM, and TB was highly correlated with that of LL (r = 0.83, 0.82, 0.72, and 0.67, respectively; P < 0.05). Muscle pH of LL was correlated with pH of SM and GM (r = 0.44 and 0.53; P < 0.05), but not (P > 0.05) pH of BF or TB. Muscle effects generally explained more variation in a*, b*, hue angle, chroma, and E than animal effects. However, the relative importance of animal effects increased as display continued. These data indicate that animal effects were consistent across muscles, though muscle effects had greater contribution to color stability variation. Furthermore, strong relationships between LL color stability and the stability of other muscles indicate that strategies developed to manage animal variation in LL color stability would beneficially affect the entire carcass.