Relationships between biochemical characteristics and meat quality of Longissimus thoracis and Semimembranosus muscles in five porcine lines

Five porcine genetic lines which represent a high proportion of European pig production were fully characterized for meat quality parameters and muscle biochemical characteristics (Longissimus thoracis, LT, and Semimembranosus, SM). The line characterisation was based on 100 animals each representing Large White, Landrace, Duroc, Piétrain (Halothane negative) and Meishan (a Meishan/Large White crossbred line) prevalent genetic backgrounds. Different meat quality parameters (pH 45min, pH ultimate, electrical conductivity, and colour measurements), as well as muscle water holding capacity, muscle metabolic and contractile traits, fibre type, size and frequencies were measured and their relationships studied. The main differences in the LT were found between the Meishan and Piétrain genetic lines, in relation to the muscle fibre size (larger in Piétrain). The Duroc line was characterized by the muscle oxidative traits and the Landrace by the high percentage of fast glycolytic fibres. In SM, Duroc and Piétrain were distinguished from Landrace and Meishan according to the metabolic and contractile characteristics of this muscle. Large White tended to lie between the other breeds for many of the traits. The measured muscle characteristics were related to differences in drip loss and marbling values and could thereby influence the eating quality of pork. Overall the results show differences between the genetic lines for a number of muscle traits which could have impact on consumer appeal and eating quality. The present findings should serve to emphasise the importance of including eating quality as a trait in breed selection.     

Lipolysis and lipid oxidation during chilled storage of meat from Large White and Pietrain pigs

The day after slaughter, six chops of Longissimus lumborum from each of 10 Large White pigs and six Piétrain pigs were packed individually under vacuum and kept at 3-4?°C in the dark. At 1, 5 and 9 days after slaughter, two chops were used for analysis of lipids, thiobarbituric acid reactive substances (TBARS), sarcoplasmic Ca(2+) and sarcoplasm and mitochondria phospholipase A(2) activity. Free fatty acid content was higher in Piétrains than in Large Whites and increased with keeping time. Total lipids of Large White pigs contained more saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA) and less polyunsaturated fatty acid (PUFA). Large Whites had less dioleoyl-linoleyl-glycerol (OOL) and Palmitoyl-oleoyl-linoleyl-glycerol (POL) and more Palmitoyl-oleoyl-stearyl-glycerol (POS) than Piétrains. The percentages of SFA and MUFA decreased and the percentage of PUFA increased with time in FFA of Large White pigs. In Piétrains, similar changes were observed between days 1 and 5, but later the percentages of SFA increased and the percentage of PUFA decreased again. TBARS tended to increase with time particularly in Piétrains. Sarcoplasmic phospholipase A(2) decreased between days 5 and 9 in both breeds. Sarcoplasmic calcium was markedly higher at day 1 in Piétrains than in Large Whites then the difference decreased. These breed differences in lipid composition differences and lipid changes during storage are considered too small to be of practical importance, for instance in influencing the choice of a breed for pork production.     

Estimation of Canadian and European lean yields and composition of pig carcasses by dual-energy X-ray absorptiometry

Dual-energy X-ray absorptiometry (DEXA) was used on 110 pig carcasses to estimate fat, lean, bone mineral content and total tissue masses of the major primal cuts and overall carcasses. The DEXA estimations were compared and used to predict the dissected lean, fat (including skin), bone and weight of primal cuts and carcasses, as well as to predict the Canadian and the European lean yields. The best relationships were obtained when predicting the weight of ham (R(2)=0.99), loin (R(2)=0.99), shoulder (R(2)=0.96), belly (R(2)=0.93), half carcass (R(2)=0.98), ham lean (R(2)=0.89), loin lean (R(2)=0.89), shoulder lean (R(2)=0.87), and the meat weight used in the estimation of the Canadian (R(2)=0.92) and the European lean yield (R(2)=0.82). While the weight of fat in the carcass and primal cuts was accurately estimated by DEXA (R(2)>0.72), DEXA carcass composition estimations were less accurate when predicting dissected bone weights (R(2)<0.54).     

Compared development of intermuscular and subcutaneous fat in carcass and primal cuts of growing pigs from 30 to 140kg body weight

A total of twenty two Large White X Landrace castrated males were slaughtered at 30, 70, 110 or 140kg BW. Carcasses were weighed and cut into four primal cuts (belly, ham, loin, and shoulder). Each cut was weighed and dissected into bone, muscle, skin, and intermuscular and subcutaneous adipose tissues. Kidney fat was also taken and weighed. Kidney fat grew more rapidly than subcutaneous or intermuscular fat averaged over all four cuts. In the shoulder and loin, about one third of total adipose tissue was in the intermuscular fraction. In the belly, there was as much (in 30-110kg BW pigs) or more (in 140kg BW pigs) intermuscular than subcutaneous adipose tissue. In the ham, the intermuscular fraction of adipose tissue grew more slowly than the subcutaneous one, so that it represented less than one fourth of total ham adipose tissue in 140kg BW pigs. Intermuscular adipose tissue exhibited a lower lipid content than subcutaneous adipose tissue, whatever the body weight, but the differences in lipid content between the adipose tissues decreased with increasing weight. These results show that the relative development of intermuscular and subcutaneous adipose tissues differs according to anatomical location.     

Comparison of the performances of Nero Siciliano pigs reared indoors and outdoors. 1. Growth and carcass composition

A total of 78 female and male Nero Siciliano pigs were used. Forty-one pigs were reared following the traditional management system, 37 pigs were reared in pens with a small outdoor paddock and fed to appetite using commercial rations according to the growing period. Both male and female pigs were castrated. All pigs were weighed and measured periodically. Body measurements included height at withers, chest girth, body length, width at shoulders and at rump. Age and body weight at slaughter ranged respectively from 371 to 572 days and from 79 to 113 kg. The carcasses were weighed and dissected into lean, fat and bone cuts. In the early and final stages indoor-pigs grew faster than those reared outdoors. Trends in body length were similar for the two rearing systems, for width at shoulders and rump, chest girth and height at withers, indoor pigs showed higher values than the outdoor ones. Carcasses of similar weight were longer in outdoor than in indoor pigs but the latter showed greater subcutaneous fat thickness. Outdoor pigs had the lowest dressing percentage and the highest percentage of lean cuts, such as shoulder and ham, but not of neck and loin. Sex did not significantly affect the analysed characteristics.     

Influence of pig crossbreed on the composition, volatile compound content and flavour of dry cured ham

The extraction of volatile compounds from dry-cured ham using a dynamic head-space method coupled with gas chromatography mass-spectrometry (GC-MS) enabled the identification of a large number of components. Some of these compounds exhibited intense sensory characteristics during odour assessment. Using similar technology, the effect of pig crossbreeds: Landrace × Large-White, Duroc × Gascon-Meishan, Piétrain × Gascon-Meishan and Large-White × Gascon-Meishan, on both volatiles and the flavour of dry-cured hams was limited, although differences were observed in aromatic compounds like 1-octen-3-ol (mushroom), 2,3-butanedione and acetoin (butter like).     

Collagen content of meat carcasses of known history

Thirteen beef carcasses and twenty-seven pig carcasses were analysed for collagen content. The beef carcasses were drawn from four breeds and four levels of fatness. They were dissected into ten joints: from the forequarter; shin, brisket, Jacob's ladder, clod, sticking, fore-rib, chuck: from the hindquarter; leg, thin flank and other joints. Samples of each joint were analysed for fat, moisture and collagen. Samples of the total forequarter and hindquarter meat were also analysed.

The pig carcasses were drawn from three weight groups and three levels of fatness. Samples from each carcass were analysed for fat, moisture and collagen. Six selected pigs were dissected into five joints: hand, collar, back, streak and ham. Samples of each joint were analysed as described above.

Results from beef carcasses showed that collagen in the forequarter (3·2% wet fat-free) was significantly higher than in the hindquarter (2·7% wet fat-free). Within the forequarter collagen in the shin (4·8% wet fat-free) was significantly higher than in the other six joints. Within the hindquarter percentage collagen was significantly highest in the leg (4·2% wet fat-free). There were no significant breed differences.

Results from pig carcasses showed an overall mean value for collagen of 2·3% wet fat-free. Percentage collagen was significantly highest in the hand (2·9% wet fat-free).     

Lipid composition of adipose tissue and muscle in pigs with an increasing proportion of Meishan genes

The purpose of this study was to estimate the effect of the proportion of Meishan (MS) genes upon the lipid composition of longissimus dorsi and trapezius muscles and perirenal and s.c. dorsal adipose tissues. Five groups of 11-15 pigs with 0, 12·5, 25, 37·5 and 50% MS genes were made up from a large herd of crossbred animals (0-100% MS dams × Piétrain sires). Results showed that: (1) the i.m. lipid content was higher in 1 2 MS than in controls and 1 4 MS pigs. Differences in the fatty acid composition of i.m. lipids, as related to genotype, depended more particularly on muscle fatness as the fatty acid compositions of triglycerides and phospholipids were little affected by the genotype. (2) The weight of perirenal and s.c. dorsal adipose tissues increased with the proportion of MS genes. Differences in the chemical composition of the adipose tissues were not related to the proportion of MS genes. The fatty acid composition was little affected by the genotype. Although the levels of polyunsaturated fatty acids decreased with increasing proportion of MS genes, these small variations had no marked influence on adipose tissue quality.     

Characterization of cutability and palatability attributes among different slaughter groups of beef cattle

Fifteen slaughter cattle from five groups (Charolais crossbred bulls, Brahman crossbred steers, Holstein steers, mixed-Exotic crossbred heifers and Hereford-Angus crossbred steers) were randomly selected from a commercial feedlot. Time-on-feed was 108, 114, 102, 108 and 145 days for the aforementioned groups, respectively. Carcasses from Charolais crossbred bulls had the highest percentage yield of chuck and round, but the lowest percentage yield of loin; hereford-Angus crossbred steers had the lowest percentage yield of round and Holstein steers had the lowest percentage yield of rib. Carcasses from Charolais crossbred bulls had the highest percentage yield of major retail-ready subprimals and lean trim, Hereford-Angus crossbred steers had the highest percentage yield of fat trim and Holstein steers had the highest percentage yield of bone from the major wholesale cuts. Mean percentage yields of closely trimmed, boneless retail cuts were highest for carcasses from the bulls and lowest for carcasses from the Hereford-Angus steers. Although Holstein steer carcasses had less fat trim than Brahman-crossbred steers mixed-Exotic heifers, this advantage was largely offset by their higher percentage of bone. Loin steaks from carcasses of Charolais crossbred bulls, Holstein, mixed-Exotic heifers were comparable (P > 0·05)with those of Hereford-Angus steers for shear force and sensory panel tenderness ratings. However, loin steaks from carcasses of Brahman-crossbred steers had significantly higher (P < 0·05) shear force values (least tender) and lower (P < 0·05) tenderness and overall palatability ratings. No diffeerences (P > 0·05) were found for flavor desirability of loin steaks among any of the groups. For bottom round steaks, Hereford-Angus steers received the highest palatability ratings while those from Holstein steers received the lowest palatability ratings.     

Effect of Breed on Fatty Acid Composition and Lipogenic Enzyme Abundance in the Subcutaneous Adipose Tissue of Pigs

This study investigated the role of lipogenic enzyme expression in breed‐specific fat deposition in pigs. Objectives: (i) determine effect of breed on the relative abundance of the key lipogenic enzymes stearoyl‐CoA desaturase (SCD), delta‐6 desaturase (Δ6D), and fatty acid synthase (FAS) in pig subcutaneous adipose tissue. (ii) Investigate breed‐specific relationships between lipogenic enzyme abundance and fatty acid composition. Large White × Piétrain, Piétrain, and Duroc × Piétrain pigs were used. Expression of SCD, Δ6D, and FAS was analyzed by Western blotting. Fatty acid composition was determined by gas chromatography. FAS protein in Large White × Piétrain pigs was similar to the Piétrain breed, but was significantly higher than Duroc × Piétrain. A positive relationship was found between FAS abundance and the saturated fatty acids (SFAs), for Large White × Piétrain pigs, but not for the other breeds. Δ6D was significantly higher in Large White × Piétrain compared with Duroc × Piétrain and Piétrain. This was accompanied by significantly higher total n?3 poly‐unsaturated fatty acids (PUFAs) in the Large White × Piétrain when compared to the other breeds. Conclusions: (i) increased subcutaneous adipose tissue SFA content in Large White × Piétrain pigs (but not Piétrain and Duroc × Piétrain) is related to increased abundance of FAS protein; (ii) high n?3 PUFA content in Large White × Piétrain pigs is related to activation of Δ6D protein synthesis; (iii) SCD and Δ6D abundance does not contribute to between‐breed differences in MUFA and n?6 PUFA content of pig subcutaneous adipose tissue.     

Differences in composition, muscularity, muscle:bone ratio and cut dimensions between six lamb genotypes

Carcass measurements and composition data were obtained for 198 lambs representing two sexes (104 cryptorchids, 94 ewes). Dorsal images of 166 of the carcasses were obtained on the slaughter chain using a video camera. The lambs were sired by a selection of Poll Dorset (PD), Texel (T), Border Leicester (BL) and Merino (M) rams, born to Border Leicester × Merino (BLM) and Merino (M) ewes giving 6 genotypes (PD × BLM, T × BLM, PD × M, T × M, BL × M, M × M). From the right hindleg and chump, the following muscles were dissected and weighed: semimembranosus, adductor femoris, semitendinosus, biceps femoris, and quadriceps femoris. The femur was weighed, the length measured and a muscularity value calculated as described by Purchas, et al. (1991, Meat Sci., 30, 181).

Merino cryptorchid lambs were significantly (P < 0.05) leaner, as measured by GR tissue depth (for explanation, see MATERIALS AND METHODS) adjusted to a mean carcass weight of 24.2 kg, than BL × M lambs, but there was no difference between genotypes within the ewe group (mean carcass weight of 17.1 kg). Genotype differences were found for conformation using the EUROP scoring system. Merino lambs had a greater proportion (P < 0.001) of poorer scores, particularly compared to PD × BLM and T × BLM carcasses. The BL × M carcasses had a significantly (P < 0.05) smaller m. longissimus thoracis et lumborum area than other genotypes with no difference between carcasses of T and PD sires.

Muscularity values for the BL × M and M lambs were significantly (P < 0.05) lower than the other crosses but not different from each other. Carcasses from T sires had significantly (P < 0.05) higher muscularity values than those from PD sires. A negative association (r = −0.56) was found between EUROP scores and muscularity when carcass differences were adjusted for, but significant differences between genotypes for muscularity were not necessarily carried through to differences in EUROP conformation score. BL × M carcasses had the lowest muscle:bone ratio and T × M the highest with M carcasses having similar ratios to carcasses from PD-sired lambs. Only small differences were found between genotypes for composition of the hindleg, the exception being BL × M carcasses of both sexes which were significantly (P < 0.05) fatter than T × BLM, T × M and PD × M carcasses. Carcasses from T sires had significantly (P < 0.05) more muscle in the hindleg than carcasses from PD sires, with the differences being greater in the heavier cryptorchids (1.8%) than the ewes (1.1%). There was no consistent effect of genotype on the cross-sectional areas of the round and topside cuts within either sex.

Differences between genotypes for the proportion of the carcass attributed to the round were small and only for BL × M ewe carcasses was this cut significantly lighter (P < 0.05) than from all other genotypes, except the PD × BLM carcasses. This trend was similar for the topside and silverside cuts. A moderate correlation (r = 0.46; P < 0.001) was found between muscularity values determined by dissection and those predicted using the equations of Hopkins et al. (1996, Proc. Aust. Soc. Anim. Prod., 21, 181) based on carcass width measurements taken from video images.     

Effect of age and cut on the nutritional content of South African beef

The physical composition and nutrient content of different age group carcasses and cuts of South African beef from equal fat classes were investigated. Carcasses from three different age groups and various fatness levels within each, were obtained on the commercial market. The physical composition of each right side cut (n = 270) was assessed and analysed for raw nutrient content, while each left side cut was cooked prior to analyses.     

Relation between muscular development and muscle collagen content in pigs

The relationship between muscle collagen content and muscular development was investigated in the pig using eight Large Whites, eight halothane-negative (HN) and eight halothane-positive (HP) Pietrain pigs. Three muscles varying in the degree of hypertrophy in Pietrain pigs as compared to Large White pigs were studied. Pietrain pigs had higher loin and ham percentages, as well as higher muscle to bone ratio in the ham than Large White pigs. A trend to lower collagen contents in Pietrain pigs as compared to Large White pigs was observed in biceps femoris and longissimus dorsi muscles, although the differences were not significant. On the whole, there does not seem to be any clear relationship between muscle collagen content and muscular development in the porcine species.     

Cold-shortening toughness in excised pork M. Longissimus dorsi

Excised pork M. Longissimus dorsi from six Large White Cross pigs were subjected to a range of chilling rates using temperatures between 20°C and -20°C. Onset of rigor at 20°C varied from 3 to 7.5 h between animals and rigor was complete in 6.5 to 15 h. Cold-shortening was induced when samples were chilled in air or liquid at 3°C or below but not at 5°C or ambient. The highest cooling rate, using liquid at -1°C, reduced the meat samples to 10°C in about 1 h and induced 34% shortening. After ageing for 5 days at 3°C in 26 h. Considering all chilling rates, toughness increased as the time to reach 10°C decreased to 3 h or less. Extensive cold-toughening would be unlikely to occur in current UK commerce and any toughening which did occur would be confined to Longissimus dorsi M. in about 20% of carcasses. The projected increased introduction of very rapid cooling, particularly in conjunction with lean pig production and hot deboning of pork, could toughen all cuts in about 60% of carcasses.     

Eating quality of meat from European × Chinese crossbred pigs

Meat from half-Chinese crossbred pigs was compared with meat from purebred European pigs for chemical composition and eating quality. In a first experiment, purebred Pietrain pigs were compared to Pietrain × Chinese (Meishan or Jia Xin ) pigs for sensory qualities as assessed by a taste panel. In a second experiment, purebred Large Whites were compared to Large White × Meishan pigs for chemical composition and eating quality as assessed by both taste panel and consumer testing. The lipid and collagen content in the meat were higher in the Large White × Chinese crossbred pigs than in the purebred Large White pigs. In both experiments, meat from half-Chinese cross bred pigs was judged more tender, more juicy and more tasty than meat from purebred European pigs by the taste panel as well as by consumers. However, the latter judged that the overall acceptability of the meat from half-Chinese pigs was not better, probably due to the excessive amount of visible fat.     

Effects of crossbreeding Mexican Pelibuey sheep with Rambouillet and Suffolk on carcass traits

Fifty nine lambs: Pelibuey (P), Suffolk×Pelibuey (SP) and Rambouillet×Pelibuey (RP), were used to evaluate the effect of crossbreeding on carcass characteristics and composition. Following carcass evaluation, muscle, bone, subcutaneous, seam, internal, total fat and other tissues were dissected. Carcass dressing percentage was similar across the three genotypes. The genetic group did not influence the percentage of cuts, except for shoulder percentage. Pelibuey carcasses had less fat thickness than RP and more kidney, pelvic and heart fat than SP. Muscle percentage was lower for RP (51.27±0.68) compared to P (54.01±0.61) and SP (53.78±0.58) carcasses, respectively. Consequently, the RP group showed the highest proportion of total fat (19.66±1.00). In general, RP carcasses had the lowest meat cutability. In conclusion, carcass yield of Pelibuey lambs was not improved by the cross with either Rambouillet or Suffolk breeds.     

Variations in meat quality in live halothane heterozygotes identified by biopsy samples of M. longissimus dorsi

The meat quality of halothane heterozygotes (Nn) was investigated using British Landrace (n = 18) and Landrace × Large White pigs (n = 67). Normal and PSE meat were identified in both breeds using M. longissimus dorsi (LD). In Landrace × Large White Nn pigs, the potential meat quality identified using small biopsy LD samples (500 mg) showed a wide spectrum in water-holding capacity (WHC), ranging from normal (43%) to PSE (57%). Predictions of meat quality in live pigs were confirmed from post-mortem assessments of LD samples based on pH(1) and fibre optic probe measurements. Our results show that Nn pigs have the propensity to produce a higher proportion of PSE than normal carcasses. The predictive meat quality test performed on small biopsy LD samples offers an opportunity not currently available to the pig industry, to select Nn pigs with the potential to produce pork of superior WHC.     

Predicting pork carcass and primal lean content from electromagnetic scans

Fifty-four whole, pre-rigor, eviscerated carcasses (74.1±kg) were selected over a 5-week period to represent carcasses marketed to a Northwest Iowa packing plant during the fall season. Carcasses (spanning 40.7-65.2% carcass lean) were electromagnetically (EM) scanned before entering the chiller. Carcass right sides were fabricated and weights were recorded for each jowl, ham, loin, Boston butt, picnic shoulder, neckbone, sparerib, and belly. Each component was skinned and dissected into external fat, internal (seam) fat, bone, and lean with corresponding weights recorded. Regression equations were derived from points and areas taken from the EM scan curve. The best 5-variable equations were developed for total carcass lean (R(2)=0.9502; RMSE=1.31 kg), percentage carcass lean (R(2)=0.8789; RMSE=1.88%), ham lean (R(2)=0.8475; RMSE=0.755 kg), loin lean (R(2)=.8511; RMSE=0.781 kg), Boston butt lean (R(2)=.7251; RMSE=0.505 kg), picnic lean (R(2)=0.7387; RMSE=0.464 kg), and commodity, component carcass value (R(2)=0.9458; RMSE=$3.24).     

Microbiological Contamination and Primal Cut Yields of Skinned and Scalded Pork Carcasses

Microbiological contamination was determined in core samples from the surface of the ham, shoulder, belly and back of skinned and scalded pork carcasses. Aerobic plate counts of mesophilic organisms indicated that ham and shoulder areas of scalded carcasses had higher bacterial numbers than skinned carcasses. Contamination on the back of the carcass was similar for skinned and scalded carcasses, while skinned carcass bellies had slightly higher counts than did scalded bellies. Numbers of psychrotrophic bacteria were negligible in all cases. Weights of primal cuts were compared in skinned and scalded carcasses by alternately skinning one side of each of 23 pork carcasses, while the other side was left skin-on. Belly, picnic shoulder and ham yields were less for skinned sides, while the loin and Boston shoulder were not affected.