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Muscle metabolites greatly determine pork quality. However, precise threshold values which indicate its deterioration or improvement are not fully known. This study aimed to determine the influences of pork Longissimus lumborum (LL) glycogen and lactate concentrations measured at 45 min post mortem on pH, colour (L*a*b*) and drip loss (DL) measured during 144 hours post mortem in order to prescribe appropriate threshold values. The investigation used 30 gilts and 30 barrows being fattened for slaughter. After slaughter, the carcasses were assigned to groups based on the observed levels of glycogen and lactate: low GlyL with glycogen ≤35 μmol/g, GlyM with glycogen between 35 and 55 μmol/g, GlyH with glycogen >55 μmol/g; LacL with lactate ≤40 μmol/g and LacH with lactate >40 μmol/g. Lower muscle pH was noted up to 24 h post mortem in the LacH group compared to LacL (P ≤0.01). 24 h post mortem higher pH was found in GlyL than in GlyM and GlyH (P ≤0.01), which were similar. Similarly no statistical differences were noted between The GlyM and GlyH groups were also similar in L*, DL96 and DL144, with lower values found for GlyL (P ≤0.01). Compared to LacH, LacL had lower L*, DL48, DL96 and DL144 (P ≤0.01) and higher a* and b* values. Muscle pH, drip loss, L* and a* values were more affected by lactate concentration if the glycogen concentration ≥35 μmol/g muscle tissue. Thus, metabolite concentration may be a useful and valuable indicator of pork quality. Keywords: drip loss, glycolytic resources, pork colour, post-mortem muscle metabolism

The objective of this study was the comparative analysis of selected attributes of nutritional and technological quality of pork from Naïma and DanBred gilts mated with P-76 boars. The research was carried on 50 pigs (25 in each group) reared under the same environmental conditions and slaughtered at about 115±5.0 kg. Both analyzed crossbreds populations were characterized by overall good nutritional and technological quality. However the loins from DanBred×P-76 compared with those from Naïma×P-76 had significantly greater glycogen and less lactate concentration in early post mortem period, higher pH at all measurement points (besides no statistical differences in pH measured 2 hours post mortem), lower thermal drip and drip loss measured 96 and 144 hours post mortem and lower lightness (except no differences measured 48 hours post mortem). Additionally loins from DanBred×P-76 contained more protein and less water. No statistical differences in IMF content between both analysed groups were noted (their average values were below 2%). Aforementioned may suggest that crossing both Naïma and DanBred hybrids with P-76 boars may not improve IMF content or increase marbling scores to the levels preferred for culinary purposes. RESUMO: O objetivo deste estudo foi a análise comparativa de atributos selecionados de qualidade nutricional e tecnológica de suínos provenientes de marrãs Naïma e DanBred acasaladas com machos P-76. A pesquisa foi realizada em 50 suínos (25 em cada grupo) criados nas mesmas condições ambientais e abatidos com cerca de 115 ± 5,0 kg. Ambas as populações de mestiços analisadas foram caracterizadas por uma boa qualidade nutricional e tecnológica geral. No entanto, os lombos de DanBred × P-76 em comparação com os de Naïma × P-76 tinham glicogênio significativamente maior, e menor concentração de lactato no período post mortem inicial, pH mais alto em todos os pontos de medição (além de nenhuma diferença estatística no pH medido 2 horas post mortem), menor gotejamento térmico e perda de gotejamento medido 96 e 144 horas post mortem e menor leveza (exceto nenhuma diferença medida 48 horas post mortem). Além disso, os lombos de DanBred × P-76 continham mais proteína e menos água. Não foram observadas diferenças estatísticas no conteúdo do FMI entre os dois grupos analisados (seus valores médios estavam abaixo de 2%). O resumido acima pode sugerir que o cruzamento de híbridos Naïma e DanBred com machos P-76 pode não melhorar o conteúdo de IMF ou aumentar as pontuações de marmoreio para os níveis preferidos para fins culinários.

The aim of the study was to evaluate the frequencies of meat quality classes in pigs from the mass population. The study was carried out in the spring/summer season on 220 fatteners. The rearing and pre-slaughter handling conditions were the same for all animals. Slaughter and carcass handling were carried out according to the procedures used at the meat plant. The research material was similar in terms of hot carcass weight (85.27 ±3.06 kg) and lean meat content (58.02 ±2.76%). The results have shown that significant issues for the pork meat industry are acid meat (AM, with low suitability for processing) and exudative meat. The percentage of AM meat was as high as 25%, while 68% was exudative meat within the category of meat assessed as RFN (red, firm, normal). For accurate and detailed conclusions, studies must be conducted in fatteners of known origin (genotype).

This study compared the diagnostic value of pork quality evaluation methods using different pH threshold values and time-points with muscle metabolites concentration threshold values measured 45 min. post mortem in assessment of meat with lowered drip loss. Samples of 100 longissimus dorsi (LD) (Landrace × Yorkshire) × Duroc fatteners were examined after slaughter for following parameters: muscle acidity in 35 min, 2 h, 3 h, 24 h and 48 h (pH1, pH2, pH3, pH24 and pH48), colour lightness (L*, a*, b*), meat yield after curing and thermal processing in 72 °C (technological yield), water-holding capacity (WHC) and drip loss in 48, 96 and 144 h (DL48, DL96, DL144). To verify the accuracy of analysed methods two groups were distinguished according to DL48, e.g. Low DL (DL48≤4%) and High DL (DL48>4%). In High DL pH1 to pH48 were statistically lower while L*, WHC, DL48, DL96, DL144 were statistically higher (P≤0.05). On the basis of pH-dependent methods classification to RFN (red, firm, normal), PSE (pale, soft, exudative), DFD (dark, firm, dry) and AM (acid meat) was performed and then the percentage share of Low DL and High DL among meat classified as RFN was evaluated. Despite most samples were classified as RFN Low DL share among them did not exceed 50%. If meat sample shows metabolites concentration below threshold value and was assigned to Low DL (or was assigned to High DL above threshold value) it was regarded as correctly classified. The most promising cut-off point (correct classification of 73%) was 45 µmol both for glycogen and lactate. RESUMO: Neste estudo foram analisadas 100 amostras de longissimus dorsi (LD) de suinos Landrace, Yorkshire (L × Y) × Duroc (D). Dois grupos foram distinguidos de acordo com a perda por gotejamento medida 48 horas após o abate, por ex. DL baixo (DL48≤%) e DL alto (DL48> 4%). Em DL alto maior leveza (L*), capacidade de retenção de água (WHC), perda por gotejamento em 48 (DL48), 96 (DL96), 144 (DL144) e menor acidez muscular de 35 min. a 48 horas post mortem (pH1 a pH48) foram anotados (P≤0.01). A baixa participação de DL dentro das amostras classificadas como RFN (vermelha, firme, normal) com base em vários métodos de avaliação da qualidade da carne suína usando diferentes pontos de tempo de pH e valores de limiar não excederam 50%. A tentativa de uso de várias concentrações de metabólitos musculares mediu 45 min. post mortem (glicogênio, lactato e suas combinações) como valores limiares na avaliação de DL baixo e DL alto foi então realizado. Os pontos de corte mais promissores (45 µmol por g de tecido muscular tanto para glicogênio quanto para lactato) permitiram classificar corretamente 83.82% de DL baixo e 50% de DL alto respectivamente abaixo e acima deles.

The aim of this study was to determine the usefulness of single and multiple electrical conductivity measurements done directly in abattoir in pork quality attributes evaluation. 82 commercial hybrid fatteners (41 barrows and 41 gilts) originated from the same breeder and reared under the same environmental conditions were slaughtered at approximately 110 kg live weight. Electrical conductivity was measured at 35 min. (EC35) and 2 (EC2), 3 (EC3) and 24 hours post mortem (EC24). Pork quality was characterised after slaughter by meat acidity (pH) measured at 35 min. and 24 hours, meat colour parameters (CIE-L*a*b* system) at 24 h, drip loss at 48 h (DL48), 96 h (DL96) and 144 h (DL144), water holding capacity (WHC) and tenderness at 48 h and 144 h expressed by shear force (N/cm2). Electrical conductivity was rather weakly correlated with pork quality traits (the highest Pearson’s r, e.g. 0.30 was noted both for EC2 and a* and DL48). Highest Cr and Cr2 values for single and multiple electrical conductivity measurements and sets of pork quality traits were noted for drip loss and water holding capacity (0.42** and 0.29 and 0.57** and 0.32 respectively) while for most of remaining sets no statistical significance were found. It could be presumed then that electrical conductivity are not useful predictor of pork quality attributes that could be performed directly in abattoirs (besides drip loss and water holding capacity to some extent). Therefore it is suggested to revise this parameter use in pork quality evaluation however further examination covering larger population of fatteners should be performed.

The aim of the study was to evaluate the culinary and technological value of meat obtained from three-way cross fattening pigs, i.e. [Landrace (L) x Yorkshire (Y)] x Duroc (D) and [Landrace (L) x Yorkshire (Y)] x Hampshire (H). The study was carried out in spring and summer on 60 pigs divided in 2 genetic groups: (LxY) x D and (LxY) x H. The rearing and pre- and post-slaughter conditions were the same for all animals. Slaughter and post-slaughter handling of the carcasses was in accordance with the procedure in use at the meat plant. The research material was similar in terms of hot carcass weight (85.14 ±2.90 kg and 85.31 ±3.29 kg) and lean meat content (56.50 ±2.71% and 56.98 ±1.99%) within each genetic group, i.e. (LxY) x D and (LxY) x H. The significant, highly unfavourable means obtained for meat quality traits in the case of the (LxY) x H pigs, in terms of both culinary and technological suitability for processing, clearly indicates that the Hampshire breed should not be used as a paternal component in mass production of fatteners. In the case of the (LxY) x D fatteners, the highly favourable values for meat quality traits, of importance to both the consumer and the meat industry, clearly support the use of the Duroc breed as a paternal component.

The aim of the study was to determine the usefulness of criteria (pH, R1 and EC) used to determine pork quality classes (RFN, PSE, DFD and AM) in assessing culinary value characteristics of pork. The study was carried out on 320 fatteners from the mass population in the spring-autumn season. Rearing conditions, pre-slaughter handling and carcass handling were the same for all animals. The fatteners were similar in terms of hot carcass weight (87.09 ±4.05 kg) and lean meat content (56.68 ±3.01%). The statistically significant correlations found confirmed that basic pork quality criteria are suitable for assessment of selected parameters of culinary value that are important to the consumer. To obtain more precise conclusions regarding the suitability of basic pork quality criteria (pH1, pH24, pH48, R1, EC2 and EC24) for estimation of characteristics of culinary value, canonical analysis should be used to determine the relationships between two sets of variables: independent (basic criteria of pork quality classes) and dependent (basic culinary values of pork).

The aim of this study was to compare the diagnostic values of two methods in pork meat quality evaluation, that is, Method I: pH1 and pH24 and Method II: electrical conductivity (EC 2 ) and pH 24 , which included pH 24 , and their modifications, that is, Method III: pH1 and pH48 and Method IV: EC 2 and pH 48 , which included pH 48 measurement. Five meat quality classes, namely reddish-pink, firm and non-exudative (RFN), high quality (HQ), pale, soft and exudative (PSE), dark, firm and dry (DFD) and acid meat (AM) were assessed in four even-numbered genetic groups of 40 fatteners each, namely (L×Y)×D-A, (L×Y)×D-B, (L×Y)×H and (L×Y)×(D×P). The change of diagnostic method and therefore pH time measurement from 24 hours to 48 hours post mortem caused a major increase in the percentage of acid meat (AM) that was diagnosed. Most differences were observed in (L×Y)×H fatteners, namely 77.5% between Methods I and III and 75% between Methods II and IV. This increase in AM frequency indicates that as a result of significant changes in the post-mortem metabolism that occur in the meat ageing process pH 48 should be regarded as ultimate pH (pHu). Keywords : Acid meat, fatteners, post-mortem muscle metabolism

The objective of this study was to determine phenotypic relations between glycolytic potential (GP) measured 45 min postmortem and meat quality traits of stress-resistant fatteners, with consideration of carcass chilling system. The investigations involved 35 Duroc fattening pigs whose left halfcarcasses were chilled conventionally (4ºC for 24 h) and right half-carcasses were rapidly chilled in a three-phase chilling tunnel (-10ºC for 15 min, -15ºC for 25 min and -5ºC for 40 min with air velocity of 3 m/s). In this study we showed that rapid chilling significantly slows the rate of pH fall from 2 to 96 h after slaughter. The negative relationship between glycolytic potential and pH (especially 24 h postmortem) was stronger for conventionally chilled carcasses but the regression coefficient (b) does not suggest increased rate of pH fall in meat of conventionally chilled carcasses (especially compared to rapid chilling) at the later stages of conversion of muscle to meat (from 24 to 144 h after slaughter). In this investigation GP was positively correlated to drip loss at 48 h postmortem, and a stronger correlation was noted for rapidly chilled carcasses. Moreover, the regression coefficient indicates that rapid chilling to 48 h postmortem can cause a slightly higher drip loss from meat than when the carcasses are chilled conventionally (0.55 vs. 0.46 percentage points per 10 μmol/g GP). At the later stages of conversion of muscle to meat (96 and 144 h postmortem) the correlation and regression coefficients were the same regardless of the chilling system.

The aim of the study was to check whether different genotypes at acyl-CoA synthetase (ACSL4 locus, SNP G2645A) are associated with pork quality. 132 (Landrace × Yorkshire) × Duroc fatteners were genotyped by originally developed PCR-RFLP method. Upon the slaughter, the samples of longissimus lumborum muscle were taken from each carcass to determine the following parameters: content of water, protein and fat, pH (45 min, 24, 48, 96, and 144 h post mortem), electrical conductivity, drip loss, meat lightness, glycolytic potential, glycogen and lactate contents in meat. Among several associations observed, the highly significant (p

The performed experiments allowed determining to what extent meat electrical conductivity measured at two time intervals (EC90’ and EC24h) may affect significantly the selected pork meat quality parameters. The experimental material comprised 75 carcasses, of which 32 were carcasses derived from hogs of line 990 and 43 were carcasses of Danish hybrid hogs [(L x Y) x Du]. The following parameters were investigated: electrical conductivity (EC90’ and EC24h), thermal drip and water holding capacity content as well as meat texture (tenderness and juiciness). After the assessment of meat electrical conductivity, the obtained results were divided into three groups taking into consideration differences in their values: EC90’: up to 3.50 mS/cm; from 3.51 – 5.00 mS/cm; > 5.00 mS/cm, and EC24h measurement: up to 4.99 mS/cm; from 5.00 – 8.00 mS/cm; > 8.00 mS/cm. It is clear from the performed investigations that measurements of meat electrical conductivity carried out 24 h after the slaughter of animals, in comparison with the measurements taken 90’ after slaughter, was correlated with the examined meat parameters higher degree.

The objective of this study was to investigate the association of PKM2 gene with glycolytic potential and meat quality traits in three groups of fatteners - Landrace, Landrace x Yorkshire and (Landrace x Yorkshire) x Duroc. The present study was conducted on 243 fatteners, free of RYR1(T) gene, which 95 were of Landrace breed and the rest were the following crosses: 66 - Landrace x Yorkshire and 82 (Landrace x Yorkshire) x Duroc. It has been stated, that PKM2 gene (independently from the breed) was significantly associated with GP, lactate content, R(1) indicator, pH and drip loss. The presence of TT genotype may lead to increase of GP and lactate content and results in low pH(24) and pH(144) and bigger drip loss measured 96 and 144 h after the slaughter. Except for the landrace fatteners, the association of the PKM2 gene with the glycogen content has not been statistically confirmed. Statistically confirmed interaction shows, that the association of PKM2 gene with glycolytic potential and glycogen content concerns mainly the Landrace pigs. Moreover, a high (almost 89%) conformability of the genotype of PKM2 gene with the RN(-) phenotype, can serve as an additional argument in favour of the thesis.

The purpose of the studies was to demonstrate to what degree genotypes of calpastatin (CAST/RsaI) and myogenin (MYOG) genes as well as the interaction between them may affect the carcass and meat quality of pigs. The investigations were conducted on 397 stress resistant pigs (free of RYR1(T) allele). It was demonstrated that the favourable effect of the variants of CAST and MYOG genes on carcass quality traits depends on the cut. The gene variant favourably affecting the weight of ham simultaneously had a negative effect on the weight of the loin. It was also shown that the interaction between CAST and MYOG genotypes has a significant effect on backfat thickness. The effect of a given combination of CAST and MYOG genotypes on carcass traits is related to the weight of a substantial cut (ham, loin). Genotypes at loci CAST/RsaI and MYOG have a significant effect on the value of certain traits and parameters of meat quality and its technological value (genotype CAST on pH at 35min and 2, 3, 24, 48, 96, 144h post-mortem (pH(35), pH(2), pH(3), pH(24), pH(48), pH(96), pH(144), respectively), R(1) (IMP/ATP), electrical conductivity at 3 and 4h post-mortem (EC(3), EC(4)), technological yield of meat in curing and thermal processing (TY) and protein content in the muscle tissue, while genotype MYOG on pH(48), EC(35), EC(3), EC(24) and dry matter content).

The aim of this study was to determine the diagnostic value of glycolityc and energetical quantities on selected meat quality characteristics of Duroc fatteners. A total of 40 Duroc porkers were investigated. Among two analysed sets of determinants (R1 with glycogen and R1 with lactate) measured in 45 min after slaughter, the best diagnostic value for meat quality characteristics exhibit a set involving R1 and glycogen that composed determination coefficient (RC2) was 0.66 for pH measured in 45 min up to 144 h post mortem. Also, with currently used meat diagnostic methods the most useful one that explains the glycolytic and energetic quantities in the highest degree is method that exploits 5 determinants, i.e. pH1, pH24, EC2, EC24 and L*24. Higher composed determination coefficient and canonical correlation (CR) for this method was obtained for set involving R1 and lactate – 0.41 and 0.64** respectively.

Summary Low heritability of meat quality traits and the lack of their systematic registration in breeding programs have encouraged the search for single nucleotide polymorphisms (SNPs) located within genes coding the proteins involved in muscle and fat metabolism. In this report, a panel of 52 SNPs was used to find which alleles and genotypes are more/less frequent in groups of pigs differentiated by extreme value of glycolytic potential (GP) and drip loss (DL). The analysis was carried out in 52 fatteners (chosen from 246 pigs), of which 28 were Landrace and 27 Landrace x Yorkshire. Two designs were performed: I, fatteners were divided into two groups showing extreme value of GP (125 versus145), II, fatteners were divided into two groups showing extreme value of DL (6.0 versus6.0). Allele frequency differences between the phenotypic groups of extreme GL or DL were not influenced by the breed. The frequency of 52 SNPs alleles for each of group was calculated and a chi-squared test was used to estimate the significance of differences in allele frequencies between alternative groups in each experimental design. Three SNPs (DECR1, PPARGC1, MC4R) and another two (CYP21, SFRS1) showed significant differences between groups of extreme GP and DL, respectively. To exemplify and validate potential associations of candidate SNPs for GP and DL, 293 fatteners representing three commercial breeds/crosses (95 Landrace, 66 Landrace x Yorkshire and 132 Landrace x Yorkshire x Duroc were genotyped for DECR1 and CYP21 by PCR-RFLP assays. DECR1 showed significant associations with GP in Landrace and Landrace x Yorkshire x Duroc fatteners. CYP21 showed significant associations with DL in all breeds/crosses. Interestingly, the CYP21 polymorphism revealed adverse associations trend in Landrace x Yorkshire x Duroc pigs in comparison to Landrace and Landrace x Yorkshire fatteners.

The present studies aimed at an analysis of the expression level of genes PKM2 and CAST in Longissimus lumborum [LL] muscle tissue of pigs differing as regards the glycolytic potential [GP] and drip loss [DL] from the LL muscle, with reference to the genetic group. The studies covered a total of 65 pigs: 20 purebred Landrace [L], 22 crossbreeds of Landrace with the Yorkshire [L x Y] and 23 three-breed crosses (Landrace x Yorkshire) x Duroc [(L x Y) x D]. In the case of gene PKM2 one may observe in (L x Y) x D crossbreds, compared to L x Y crossbreds, an increased expression, closely related with the increase in dry matter content, including intramuscular fat, as well as a more favourable progress of glycolytic and energy metabolism during the early time post mortem (pH(45) and R(1)). Compared with Landrace animals, the lower expression of the CAST gene observed in (L x Y) x D pigs is manifested by a marked improvement of meat quality (R(1) pH(45) pH(24), pH(48)), arising from the rate of glycolytic and energy metabolism, typical for normal meat, that in effect results in its higher culinary and technological value.