The influence of fiber size distribution of type IIB on carcass traits and meat quality in pigs

The effects of detailed characteristics such as the size and proportion of type IIB fibers in longissimus thoracis muscle on carcass traits and pork quality were investigated. A total of 96 pigs were classified into four groups by the proportion of different IIB fiber sizes. Group NS (high proportion of both small- and normal-sized IIB fibers) had a higher total number (136.4) and density (231.31) of type IIB fibers, backfat thickness (37.20 mm) and intramuscular fat content (4.77%) than the other groups (P < 0.05), whereas Group NS had the lowest values of cross-sectional area (3413.85 μm²) and diameter (60.15 μm) of type IIB fiber among the groups (P < 0.05). Pig muscles with higher percentage of large IIB fibers exhibit tougher, lighter and more exudative meat than pig muscles with a higher proportion of small- or normal-sized IIB fibers. Therefore, an increase in the proportion of large IIB fibers causes poor quality of pork.     

Evaluation of QTL for carcass merit and meat quality traits in a US commercial Duroc population

Putative quantitative trait loci (QTL) regions on 5 chromosomes (SSC3, 6, 12, 15, and 18) were selected from our previous genome scans of a Duroc×Pietrain F(2) resource population for further evaluation in a US commercial Duroc population (n=331). A total of 81 gene-specific single nucleotide polymorphism (SNP) markers were genotyped and 33 markers were segregating. The MDH1 SNP on SSC3 was associated with 45-min and ultimate pH (pHu), and pH decline. PRKAG3 on SSC15 was associated with pHu. The HSPG2 SNP on SSC6 was associated with marbling score and days to 113kg. Markers for NUP88 and FKBP10 on SSC12 were associated with 45-min pH and L*, respectively. The SSC15 marker SF3B1 was associated with L* and LMA, and the SSC18 marker ARF5 was associated with pHu and color score. These results in a commercial Duroc population showed a general consistency with our previous genome scan.     

Quantitative trait loci for meat quality traits in pigs considering imprinting and epistatic effects

The aim of the research was to gain a better understanding of the genomic regulation of meat quality by investigating individual and epistatic QTL in a three-generation full-sib population (Pietrain x crossbred dam line). In total, 386 animals were genotyped for 96 markers. Analysed traits included pH, reflectance value, conductivity, and meat colour. Thirteen significant individual QTL were identified. The most significant QTL were detected on SSC1 and SSC9 for pH, on SSC4 for meat colour, and on SSC8 for conductivity, accounting for 3.4% to 4.7% of the phenotypic variance. Nine significant epistatic QTL pairs were detected accounting for between 5.7% and 10.9% of the phenotypic variance. Epistatic QTL pairs showing the largest effects were for reflectance value between two locations of SSC4, and for pH between SSC10 and SSC13, explaining 9.5% and 10.9% of the phenotypic variance, respectively. This study indicates that meat quality traits are influenced by numerous QTL as well as a complex network of interactions.     

Modelling quality variations in commercial Ontario pork production

This study explores the interactions of sensory and nutritional environment with genotype occurring in current commercial pork production in Ontario, Canada, which may interact to result in poor quality meat. The study focussed on identifying factors and signalling mechanisms that contribute to poor meat quality, in order to develop strategies to reduce the incidence of unacceptable product quality. In the first phase of the work reported here, animal behaviour and muscle metabolism studies were related to meat colour, tenderness and water-holding capacity measurements from commercially-produced pigs killed in a commercial packing plant. A partial least squares analysis was used to determine the most important of the principal production variables, peri-mortem biochemical measures and post-mortem carcass condition variables studied, in terms of their influence on water-holding, toughness and colour (L*-value). Variations between producer and kill day at the slaughterhouse were very strong contributors to variability in these three meat quality parameters, followed by pH variations. A second phase of the study is currently underway to characterize patterns of gene expression related to extremes of end-product quality and to reduce quality variations by nutritional and behavioural management strategies.     

Association of calpastatin gene polymorphisms and meat quality traits in pig

Calpastatin is associated with the rate of post mortem degradation of structural proteins due to the regulation of calpain activity. In the present research, the associations between polymorphisms within 6th intron of porcine CAST gene and several meat quality traits were analyzed. The CAST gene polymorphisms affected meat colour, pH, water holding-capacity (WHC) and texture parameters (toughness, firmness, cohesiveness, chewiness, and resilience) measured in longissimus dorsi and semimembranosus muscles. The analysis performed on the most numerous breeds maintained in Poland, suggested that the most interesting polymorphisms were CAST/HpaII and CAST/RsaI, which had the greatest effect on WHC regardless of the breed analyzed and had an effect on meat pH, firmness and toughness for most breeds. Interestingly, for almost all breeds, the significant effect of both mutations on intramuscular fat content (IMF) was detected. The provided data confirmed the use of CAST gene as a genetic marker in breeding programmes which allows performing a selection focussed on improving the quality of pork.     

Association of single nucleotide polymorphism (SNP) markers in candidate genes and QTL regions with pork quality traits in commercial pigs

Numerous reports have described genetic markers or genomic regions (QTL) associated with pork quality and/or palatability but few validation studies have been reported. Therefore, 156 SNP markers from 45 candidate genes and eight QTL regions were analyzed for association with pork quality and palatability traits from 888 pork loins. Loins were collected at three slaughter facilities and selected to represent a wide range of pork color, pH and marbling. Phenotypic data recorded included objective and subjective measures of color and marbling, purge loss, shear force, and cooking loss. Data were analyzed with SAS PROC MIXED where loin was fit as a random effect. Results indicated some of the markers tested should be useful in industry, while others are not segregating in all populations or linkage disequilibrium between markers and causative genetic variation fluctuates among populations limiting their universal utility. Genes with the largest effects on pork quality were MC4R, IGF2, CAST and PRKAG3.     

Association mapping of quantitative trait loci for carcass and meat quality traits at the central part of chromosome 2 in Italian Large White pigs

Association mapping of the central part of porcine chromosome 2 harboring QTLs for carcass and meat quality traits was performed with 17 gene-tagged SNPs located between 44.0 and 77.5 Mb on a physical map (Sscrofa10.2) in Italian Large White pigs. For the analyzed animals records of estimated breeding values for average daily gain, back fat thickness, lean cuts, ham weight, feed conversion ratio, pH₁, pH_u, CIE L*, CIE a*, CIE b* and drip loss were available. A significant QTL for fat deposition (adjusted P = 0.0081) and pH₁ (adjusted P = 0.0972) to MYOD1 at position 44.4 Mb and a QTL for growth and meatiness (adjusted P = 0.0238–0.0601) to UBL5 at position 68.9 Mb were mapped. These results from association mapping are much more accurate than those from linkage mapping and facilitate further search for position candidate genes and causative mutations needed for application of markers through marker assisted selection.     

Comparing the histochemical characteristics and meat quality traits of different pig breeds

The purpose of this study was to compare the muscle histochemical characteristics and meat quality traits between Berkshire, Landrace, Yorkshire, and crossbred pigs. A total of 594 pigs were evaluated. A clear difference between histochemical properties was observed from the results for fiber type composition. In Berkshire pigs, the area percentage of type I fibers was higher (P < 0.001) and that of type IIb fibers was lower (P < 0.05) than those of other breeds. The muscle pH_45min and pH_24h were significantly higher in Berkshire pigs. Drip loss and color parameters were significantly different between the breeds (P < 0.001). The Berkshire pigs, which showed the highest muscle pH and lowest drip loss and L^* values, contained a significantly higher percentage of type I fibers than the other breeds. By comparing the fiber type compositions of the different breeds, the results imply that the longissimus dorsi muscle of Berkshire pigs is more oxidative than that of other breeds. A high pH value in Berkshire pigs is due to a high percentage of type I fibers and a low percentage of type IIb fibers. Based on these results, we conclude that muscle fiber composition can explain in parts the variation of meat quality across and within breeds.     

Effect of protein level in commercial diets on pork meat quality

This study assessed the effect of protein level on meat quality, intramuscular and subcutaneous fat, instrumental texture and sensory attributes on Longissimus dorsi in pork. Animals were fed two experimental diets that produced two animal groups with different percentages of intramuscular fat (IMF) (1.76 vs. 2.63). There were no significant differences in meat quality or texture profile analysis parameters between IMF groups. The percentage of saturated fatty acids was also similar, but the percentage of monounsaturated was significantly higher in the group with higher IMF and the percentage of polyunsaturated fatty acids was higher in the group with lower IMF. IMF groups had little effect on the fatty acid composition of subcutaneous fat. Warner-Bratzler shear force (WBSF) values were significantly higher in the group with lower IMF, whereas tenderness was higher in the group with higher IMF. Finally, WBSF appeared to be a good predictor of the tenderness for grill-cooked pork.     

Effect of stun duration and current level applied during head to back and head only electrical stunning of pigs on pork quality compared with pigs stunned with CO(2)

The effect of current, duration and method of application of manual electrical stunning on pork carcass and meat quality attributes in comparison with stunning pigs with CO₂ was investigated. Two experiments were conducted using a total of 96 Large White×Landrace boars (homozygous dominant for the halothane gene). In Experiment 1, 48 pigs were allocated to one of six stunning treatments: CO₂ (90% in air), electrical stunning (ES) using head only (HO) tongs delivering current at a frequency of 50 Hz at 1.3 or 2.0 A for 4 s and 0.9, 1.3 or 2.0 A for 19 s. Higher drip loss occurred in M. longissimus thoracis et lumborum (LTL) muscles from ES pigs, except those stunned with 0.9 A for 19 s, compared with pigs stunned with CO₂. The incidence of pale, soft exudative (PSE) meat was higher in ES pigs, except those stunned at 1.3 A for 4 s, compared with CO₂ stunned pigs. In Experiment 2, 48 pigs were allocated to one of six stunning treatments: ES using a head to back (HB) handpiece delivering current at 1.3 or 2.0 A for 4 s and 0.9 or 1.3 A for 10 s; HO 1.3 A for 4 s or CO₂. Although stunning treatment did not influence ultimate pH, muscle lightness, tenderness or cooking loss, drip loss and PSE incidence in LTL muscles from CO₂ stunned pigs were lower compared with ES pigs. Overall, ecchymosis and bone fractures were more prevalent in ES pigs compared with CO₂ stunned pigs. This research identified that stunning pigs with CO₂ compared with manual ES lowered the incidence of bone fractures, ecchymosis, PSE and drip loss of pork.     

Effect of sugarcane diets and a high fibre commercial diet on fresh meat and dry-cured ham quality in local Caribbean pigs

The effects sugar cane (SC) diets and a milling by product diet on meat quality characteristics of fresh meat and dry-cured ham were studied on a total of 48 Creole (CR) pigs. Pigs were fed with a control soya-bean meal corn diet (C1), a soya-bean meal wheat diet (C2), a SC fresh juice diet (SC-J), or a ground cane diet (SC-G). Average BW gain was 657, 530, 546, and 200 g/d for diets C1, C2, SC-J and SC-G, respectively. Lean cuts (i.e., ham and loin) were significantly higher in SC-G than in C1 pigs (472 vs. 424 g/kg; P < 0.01); intermediate values were found for C2 and SC-J pigs (427 and 412 g/kg, respectively). The ultimate pH in LD muscle was lower in SC-J than the other groups (5.44 vs. 5.65; P < 0.01). The intra muscular fat (IMF) content in LD was significantly higher in SC-J diet and lower in SC-G diet (1.9% and 1.0%, respectively); intermediates values were found for C1 and C2 diets (1.4% on average). Ham weight losses during 6 months drying period were lower for SC-G fed pigs (9.7% vs. 12.4%; P < 0.05) whereas weight losses during the 12 months drying period were not affected by diet. The TBA value in dry-cured ham was not affected by diet (P > 0.05) whereas the fatty acids profiles of subcutaneous fat in SC-J and SC-G pigs contained more mono-unsaturated and less polyunsaturated fatty acids than in C1 and C2 groups. Significant effects of dietary treatment were found for dry-cured ham sensory quality parameters.     

Effect of different dietary levels of natural-source vitamin E in grow-finish pigs on pork quality and shelf life

Improving pork quality and shelf life is important in today’s swine industry because higher levels of DDGS are incorporated into pig diets. Relatively high level of poly-unsaturated fatty acids (PUFA) in DDGS may increase pork susceptibility to lipid oxidation and thus reduce pork shelf life. Antioxidants such as vitamin E may delay the onset of pork lipid oxidation when used as an ingredient in the diet. This experiment examined carcass characteristics, meat quality, shelf life, and color stability in pork from pigs (n = 150) fed five levels of a natural vitamin E (Nova-E) and one level of synthetic vitamin E. Natural vitamin E and synthetic vitamin E had no effect on carcass characteristics or meat quality. Increasing dietary natural vitamin E from 10 to 200 mg/kg decreased lipid oxidation. Lipid oxidation of pork chops and ground pork was similar between pigs fed 40 mg/kg and higher levels of natural vitamin E, indicating no additional benefits from supplementing beyond 40 mg/kg natural vitamin E. Supplementing 200 mg/kg synthetic vitamin E decreased pork lipid oxidation when compared to supplementing 10 mg/kg natural vitamin E. High levels of natural vitamin E or synthetic vitamin E, however, did not prevent discoloration of loin chops. These data indicate that natural vitamin E was effective to help reduce lipid oxidation and the effective minimal level of dietary supplementation appeared to be 40 mg/kg.     

Influence of meat exudates on the quality characteristics of fresh and freeze-thawed pork

The influence of the accumulated exudates released from pork loin of itself on the quality characteristics of fresh and freeze-thawed pork during cold storage was investigated. Pork loins were divided into four groups (fresh pork with exudates, fresh pork without exudates, freeze-thawed pork with exudates and freeze-thawed pork without exudates) and stored at 1.0 °C for 7 days. Exudate amount increased due to freeze-thawing and with storage, and most quality traits such as drip loss, cooking loss, tenderness, lightness, redness, and moisture content were affected by freeze-thawing (p < 0.05). Freeze–thaw increased drip loss but decreased moisture content, cooking loss, tenderness, lightness and redness of meat (p < 0.05). Microbial growth was solely affected by exudate removal and the removal of initial exudates decreased microbial growth (p < 0.05). Exudates were positively correlated with total protein content and total plate count but negatively correlated with pH and cooking loss. Therefore, removing meat exudates and avoiding freeze can slow down the quality deterioration of pork during cold storage.     

Meat quality of lambs produced in the Mesopotamia region of Argentina finished on different diets

The meat quality of Corriedale lambs (40 kg live weight) produced in the Mesopotamia region (Argentina) was assessed. These lambs had different finishing diets: only native grass pasture, ground alfalfa and alfalfa-linseed pellet (70/30). Carcass yield, longissimus dorsi area, backfat thickness, marbling, pH, meat and subcutaneous fat color, cooking loss, Warner-Bratzler shear force, fat, protein and moisture content were determined. Lambs finished on alfalfa-linseed pellet had the highest carcasses yield and backfat thickness and their meat had a lighter color (higher L^∗ value), higher marbling and tenderness than meat from lambs reared on native grass pasture. Grass-based finishing can lead to the production of leaner meat, with a more reddish color (higher a^∗ value). The ground alfalfa finishing diet seems to be intermediate between native grass pasture and alfalfa-linseed pellet with respect to carcass yield, backfat and meat color. In addition, the animals fed on ground alfalfa showed the highest muscle area.     

Performances and meat quality of two Italian pig breeds fed diets for commercial hybrids

The effects of specific diets for commercial hybrids were investigated on 6 Casertana and 11 Mora Romagnola, two endangered Italian pig breeds. Average daily gain (ADG), feed conversion index (FCI), dressing percentage and meat and fat quality of animals bred under similar environmental and nutritional conditions were compared to define their optimal slaughtering weight. Animals were fed the same diets assuming that requirements of Mora Romagnola and Casertana did not differ, and changed every 30 kg of weight gain. ADG and FCI were calculated every 15 days.

Weight gains, divided into 5 groups based on live weight (LW) of animals (60 kg, 60 < kg  90, 90 < kg  120, 120 < kg  160, >160 kg), showed higher values for Casertana than Mora Romagnola, particularly from 121 to 160 kg LW (687 g/d). Average FCI from 50 to 160 kg LW was similar in both breeds (4.2). After 403 days of trial, animals were slaughtered at about 195 kg LW. Carcass measurements showed that Casertana had higher dressing percentage and lean cuts than Mora Romagnola. Both breeds showed extraordinary high ultimate pH values of M. longissimus thoracis (5.96 and 6.15 for Casertana and Mora Romagnola, respectively) M. semimembranosus (6.37 and 6.30), showing an incomplete post mortem glycolysis. Colour of M. longissimus thoracis did not differ between breeds and was particularly dark. Chemical analysis of Casertana meat showed lower percentage of water and fat; the total amount of fatty acids (SFA, MUFA and PUFA) and the SFA/UFA ratio did not show significant differences between breeds.

Results showed that from a growth point of view the optimal slaughtering weight of Casertana and Mora Romagnola should not exceed 160 kg LW. Both breeds had an uncommon reactivity to stress probably due to interactions of genetic, nutritional and management factors.     

Effects of lairage time on welfare indicators,energy metabolism and meat quality of pigs in Beijing

A total of forty Duroc–Landrace–Large White female pigs (90 ± 5 kg) were used to study the effects of different lairage times (0 h, 3 h, 8 h, 24 h) on welfare, energy metabolism and meat quality. The results showed that lairage time of 3 h led to a lower blood cortisol, a decreased drip loss and a delayed degradation of glycogen in muscles compared with pigs without rest, while lairage times of 8 h and 24 h resulted in a significant increase in pork toughness. It was concluded that three hours of lairage was appropriate to reduce pre-slaughter stress and obtain better meat quality for pigs transported for 4 h in winter, under the most frequent commercial conditions in Beijing, China. No lairage, or excessively long lairage time, might compromise animal welfare and meat quality.     

The effect of transportation on the expression of heat shock proteins and meat quality of M. longissimus dorsi in pigs

This study investigates the effect of different transport times on meat quality and the correlation between meat quality and Hsp expression in M. longissimus dorsi (LD) of pigs. After transportation for 1 h, 2 h or 4 h, respectively, blood plasma creatine kinase (CK) and lactate dehydrogenase (LDH) increased. The LD meat from 1 h and 2 h transported pigs had lower initial and ultimate pH values (pHi and pHu, respectively), higher drip loss and L^∗ values compared to controls, indicating a higher likelihood of pale, soft and exudative (PSE) meat. Meat quality was lower after 2 h compared to 1 h or 4 h of transport. All four Hsps tested (alpha-B-crystalline, Hsp27, Hsp70 and Hsp90) by ELISA in the LD tissue of pigs tended to decrease after transportation. One possible mechanism resulting in poor meat quality in the LD after transport seems to be a decline in Hsp expression.     

The influence of pork quality traits and muscle fiber characteristics on the eating quality of pork from various breeds

The purpose of this study was to compare parameters associated with pork quality, muscle fiber, and eating quality among various breeds, and to examine if differences in eating quality were associated to pork quality and muscle fiber characteristics. For carcass and pork quality, although there were significant differences among breeds, the values of parameters in all pigs were assigned a normal quality class, a likely outcome of the similarity in the area percentage of type I and IIB fibers. For eating quality, pork loins from Berkshire pigs were more tender and full of pork flavor than Landrace and Yorkshire pigs. Except juiciness and mouth coating, over 20% of the variability in the eating quality parameters can be explained by pork quality traits and muscle fiber characteristics using multiple regression analysis. Furthermore, differences in muscle pH_24 h, cooking loss, shear force, and NPPC marbling score could explain a large proportion of variation in eating quality parameters associated with the texture of pork.     

Comparison of the performances of Nero Siciliano pigs reared indoors and outdoors: 2. Joints composition, meat and fat traits

A study on the effect of rearing system on tissue composition of principal joints and chemical–physical traits of meat and subcutaneous fat, was carried out on a local pig breed. A total of 78 Nero Siciliano pigs was used; 41 pigs were reared in woods, 37 pigs were reared in pens and fed a commercial diet. Weight at slaughter was 101.9 and 88.2 kg for indoor and outdoor pigs, respectively. Means were estimated at 77 kg of live weight. At ham dissection outdoor-pigs showed higher percentages of lean (58% vs. 55%) and lower subcutaneous fat (31% vs. 34%). In Longissimus lumborum outdoor-pigs showed a higher intramuscular fat percentage (4.3% vs. 3.3%), a lower protein content (22.2% vs. 23.4%), and higher free water (9.6 vs. 7.9 cm²). Outdoor pigs produced more light (L^*=50 vs. 46.7) and more yellow (b^*=5.84 vs. 4.88) meat. Subcutaneous fat of outdoor pigs showed higher percentages of MUFA (53.3% vs. 47.2%) and lower percentages of PUFA (10.85% vs. 14.45%), no differences were found for n−3 PUFA. Outdoor-pigs had lower atherogenicity (0.48 vs. 0.53) and thrombogenicity (1.03 vs. 1.21) indices.     

Effects of myosin heavy chain isoforms on meat quality, fatty acid composition, and sensory evaluation in Berkshire pigs

The main objective of this study was to investigate the effects of myosin heavy chain (MHC) isoforms on meat and sensory quality in Berkshire pigs. A total of 85 pigs were evaluated, and muscle samples were taken for the analyses of MHC isoform, meat quality, fatty acid composition, and sensory evaluation. Content of the MHC slow isoform was significantly correlated with pH(24h) (r=0.26, P<0.05) and drip loss (r=-0.32, P<0.01), although the content of MHC isoforms showed limited relationships with individual fatty acids. In the case of sensory evaluation of meat by a trained panel test, the MHC fast/slow ratio was correlated with the juiciness (r=-0.33, P<0.01), off-flavor (r=0.34, P<0.01), tenderness attributes (r=-0.43 to -0.47). These results imply that the content of MHC isoforms can influence various aspects of quality including pork and sensory quality in Berkshire pigs.