• Asian-Australasian Journal of Animal Sciences
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• v.33 no.5
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• pp.704-711
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• 2020

Objective: Muscle fiber types, numbers and area are crucial aspects associated with meat production and quality. However, there are few studies of pig muscle fibre traits in terms of the detection power, false discovery rate and confidence interval precision of whole-genome quantitative trait loci (QTL). We had previously performed genome scanning for muscle fibre traits using 183 microsatellites and detected 8 significant QTLs in a White Duroc×Erhualian F₂ population. The confidence intervals of these QTLs ranged between 11 and 127 centimorgan (cM), which contained hundreds of genes and hampered the identification of QTLs. A whole-genome sequence imputation of the population was used for fine mapping in this study. Methods: A whole-genome sequences association study was performed in the F₂ population. Genotyping was performed for 1,020 individuals (19 F₀, 68 F₁, and 933 F₂). The whole-genome variants were imputed and 21,624,800 single nucleotide polymorphisms (SNPs) were identified and examined for associations to 11 longissimus dorsi muscle fiber traits. Results: A total of 3,201 significant SNPs comprising 7 novel QTLs showing associations with the relative area of fiber type I (I_RA), the fiber number per square centimeter (FN) and the total fiber number (TFN). Moreover, one QTL on pig chromosome 14 was found to affect both FN and TFN. Furthermore, four plausible candidate genes associated with FN (kinase non-catalytic C-lobe domain containing [KNDC1]), TFN (KNDC1), and I_RA (solute carrier family 36 member 4, contactin associated protein like 5, and glutamate metabotropic receptor 8) were identified. Conclusion: An efficient and powerful imputation-based association approach was utilized to identify genes potentially associated with muscle fiber traits. These identified genes and SNPs could be explored to improve meat production and quality via marker-assisted selection in pigs.

• Food Science of Animal Resources
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• v.38 no.6
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• pp.1305-1314
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• 2018

To investigate relationships of electronic taste-traits with muscle fiber type composition (FTC) and contents of nucleotides, porcine longissimus lumborum (LL), psoas major (PM), and infra spinam (IS) muscles were obtained from eight castrated LYD pigs. FTC and taste-traits in these three porcine muscles were measured by histochemical analysis and electronic tongue system, respectively. IS had significantly higher proportion of type I fibers while LL had significantly higher proportion of type IIB than other muscles (p<0.05). IS had the highest inosine monophosphate (IMP) content while LL had the lowest IMP content (p<0.05). In contrast, LL had significantly higher hypoxanthine content compared to PM and IS (both p<0.05). For taste-traits, IS had significantly higher umami and richness values but lower sourness value than LL and PM (p<0.05). Sourness and astringency values of LL were significantly higher than those of IS (p<0.05). The proportion of type IIB fiber was positively correlated with sourness and astringency but negatively correlated with saltiness. These results suggest that sourness and astringency tastes are increased with increasing proportions of type IIB fibers in porcine muscles due to increase of hypoxanthine content. These results also imply that umami and richness tastes are increased with increasing contents of type I and IIA fibers because of increased IMP content in porcine muscles.

• Food Science of Animal Resources
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• v.39 no.2
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• pp.197-208
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• 2019

The aim of this study was to investigate the relation of sensory quality traits of cooked beef to fresh meat quality and histochemical characteristics, especially muscle bundle traits, in the longissimus thoracis muscle of Hanwoo steers. Cooking loss negatively correlated with softness, initial tenderness, chewiness, rate of breakdown (RB), and amount of perceptible residue (AR) after chewing (p<0.05), and drip loss showed negative correlation with RB and AR (p<0.05). All the attributes of tenderness exhibited negative correlation with the Warner-Bratzler shear force value (p<0.05). Marbling score and the intramuscular fat (IMF) content showed positive correlation with all the organoleptic characteristics, including tenderness attributes, juiciness, and flavor (p<0.05). Regarding histochemical characteristics, muscle fiber size did not have a significant correlation with all the sensory quality traits, although the area percentage of type I fiber was related with softness, initial tenderness, and chewiness (p<0.05). On the contrary, the characteristics of muscle bundle were related to all the sensory tenderness attributes (p<0.05), and the sensory tenderness increased with smaller muscle bundle size (p<0.05). These results suggest that the IMF content and bundle characteristics can be used as indicators for explaining the variations in sensory tenderness in well-marbled beef.

• Food Science of Animal Resources
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• v.37 no.5
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• pp.716-725
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• 2017

The objective of this study was to determine the relationship between composition of muscle fiber types and meat quality traits of eight major muscles from Hanwoo steers. Longissimus lumborum (LL), psoas major (PM), semimembranosus (SM), semitendinosus (ST), gluteus medius (GM), triceps brachii (TB), rectus abdominis (RA) and superficialis flexor (SF) muscles were obtained from 9 Hanwoo steers and subjected to histochemical analysis. There were significant (p<0.05) differences in fiber number percentage (FNP) and fiber area percentage (FAP) of fiber types among these 8 major muscles. SF had the highest FNP of type I (55.9%), followed by PM (46.4%), TB (45.4%), RA (38.5%), LD (36.8%), GM (36.0%), SM (22.2%), and ST (18.8%). FAP of type IIB ranged from 9.9% in SF to 58.7% in ST. Meat quality traits, including fat content, myoglobin content, collagen content, CIE $L^*$ and $a^*$, drip and cooking loss, sarcomere length and Warner-Bratzler shear force, were all significantly (p<0.05) different among these muscles. Due to such diversities among these 8 muscles, lack of correlations were found between fiber type composition and meat quality traits. These results suggest that correlation for each individual muscle should be used to improve meat quality and profitability of retail beef cuts.

• Food Science of Animal Resources
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• v.39 no.6
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• pp.988-999
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• 2019

To investigate the relationship between muscle fiber characteristics and meat quality traits by age of Korean native black goat (KNBG), four muscles (longissimus dorsi, LD; psoas major, PM; semimembranosus, SM; gluteus medius, GM) were obtained from five adult goat (AG; 18 months old) and five young goat (YG; 9 months old). PM muscle had the highest fiber number percentage (FNP) and fiber area percentage (FAP) of type I, followed by SM, GM, and LD muscles. FNP and FAP of type IIB were significantly (p<0.001) higher in AG than those in YG. YG had higher L^* values but lower b^* values than AG. The highest L^* and b^* values were observed in LD muscle (p<0.001). Age and muscle type had detrimental (p<0.001) effect on shear force and collagen content for all muscle in AG as compared to YG. YG had significantly (p<0.001) higher myofibrillar fragmentation index (MFI) than AG for all four muscles. These results suggest that muscle fiber compositions of different muscle types of KNBG depend on age, resulting in variations of meat color, MFI, collagen content, and shear force.

• Animal Bioscience
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• v.34 no.7
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• pp.1193-1201
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• 2021

Objective: According to market demand, meat duck breeding mainly includes 2 breeding directions: lean Pekin duck (LPD) and fat Pekin duck (FPD). The aim of the present study was to compare carcass and meat quality traits between 2 strains, and to provide basic data for guidelines of processing and meat quality improvement. Methods: A total of 62 female Pekin ducks (32 LPDs and 30 FPDs) were slaughtered at the age of 42 days. The live body weight and carcass traits were measured and calculated. Physical properties of breast muscle were determined by texture analyzer and muscle fibers were measured by paraffin sections. The content of inosine monophosphate (IMP), intramuscular fat (IMF) and fatty acids composition were measured by high-performance liquid chromatography, Soxhlet extraction method and automated gas chromatography respectively. Results: The results showed that the bodyweight of LPDs was higher than that of FPDs. FPDs were significantly higher than LPDs in subcutaneous fat thickness, subcutaneous fat weight, subcutaneous fat percentage, abdominal fat percentage and abdominal fat shear force (p<0.01). LPDs were significantly higher than FPDs in breast muscle thickness, breast muscle weight, breast muscle rate and breast muscle shear force (p<0.01). The muscle fiber average area and fiber diameter of LPDs were significantly higher than those of FPDs (p<0.01). The muscle fiber density of LPDs was significantly lower than that of FPDs (p<0.01). The IMF of LPDs in the breast muscle was significantly higher than that in the FPDs (p<0.01). There was no significant difference between the 2 strains in IMP content (p>0.05). The polyunsaturated fatty acid content of LPDs was significantly higher than that of FPDs (p<0.01), and FPDs had higher saturated fatty acid and monounsaturated fatty acid levels (p<0.05). Conclusion: Long-term breeding work resulted in vast differences between the two strains Pekin ducks. This study provides a reference for differences between LPD and FPD that manifest as a result of long-term selection.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.10
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• pp.1565-1574
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• 2018

Objective: The aim of the present study was to identify genetic variants based on RNA-seq data, obtained via transcriptome sequencing of muscle tissue of pigs differing in muscle histological structure, and to verify the variants' effect on histological microstructure and production traits in a larger pig population. Methods: RNA-seq data was used to identify the panel of single nucleotide polymorphisms (SNPs) significantly related with percentage and diameter of each fiber type (I, IIA, IIB). Detected polymorphisms were mapped to quantitative trait loci (QTLs) regions. Next, the association study was performed on 944 animals representing five breeds (Landrace, Large White, Pietrain, Duroc, and native Puławska breed) in order to evaluate the relationship of selected SNPs and histological characteristics, meat quality and carcasses traits. Results: Mapping of detected genetic variants to QTL regions showed that chromosome 14 was the most overrepresented with the identification of four QTLs related to percentage of fiber types I and IIA. The association study performed on a 293 longissimus muscle samples confirmed a significant positive effect of transforming acidic coiled-coil-containing protein 2 (TACC2) polymorphisms on fiber diameter, while SNP within forkhead box O1 (FOXO1) locus was associated with decrease of diameter of fiber types IIA and IIB. Moreover, subsequent general linear model analysis showed significant relationship of FOXO1, delta 4-desaturase, sphingolipid 1 (DEGS1), and troponin T2 (TNNT2) genes with loin 'eye' area, FOXO1 with loin weight, as well as FOXO1 and TACC2 with lean meat percentage. Furthermore, the intramuscular fat content was positively associated (p<0.01) with occurrence of polymorphisms within DEGS1, TNNT2 genes and negatively with occurrence of TACC2 polymorphism. Conclusion: This study's results indicate that the SNP calling analysis based on RNA-seq data can be used to search candidate genes and establish the genetic basis of phenotypic traits. The presented results can be used for future studies evaluating the use of selected SNPs as genetic markers related to muscle histological profile and production traits in pig breeding.

• Food Science and Biotechnology
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• v.17 no.5
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• pp.965-970
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• 2008

The objective of this study was to examine the relationship between instrumental tenderness parameters and histochemical characteristics in the porcine longissimus dorsi muscle, and to investigate a comparison between tenderness parameters such as the Warner-Bratzler shear-force (WBS) and texture profile analysis (TPA). A negative relationship between WBS and fiber area was observed. However, there was no significant relationship between hardness and muscle fiber area. The percentage of fiber type IIb exhibited a positive correlation with hardness. There was a negative relationship between the type IIa composition percentage and hardness. This study showed that some muscle fiber characteristics were related to WBS and TPA parameters, especially hardness.

• Food Science of Animal Resources
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• v.37 no.6
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• pp.948-954
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• 2017

The objective of this study was to investigate the relationship between muscle fiber characteristics and fatty acid composition of four major muscles in Korean native black goat (KNBG). Longissimus lumborum (LL), psoas major (PM), semimembranosus (SM), and gluteus medius (GM) were obtained from five male KNBGs of 36 mon of age and subjected to histochemical analysis and to determine fatty acid composition and meat quality traits. There were significant (p<0.05) differences in fiber number percentage (FNP) and fiber area percentage (FAP) of fiber types among these four muscles. PM had the highest FNP of type I and the lowest FNP of type IIB, while SM had the highest FNP of type IIB. The highest fat content was observed in LL while SM had the lowest fat content. The proportions of SFA and MUFA were significantly (p<0.05) different among four muscles due to differences in the majority of fatty acids such as oleic (C18:1) and palmitic (C16:0) acids. The PUFA/SFA ratio was significantly (p<0.05) different among four muscles, and the highest PUFA/SFA ratio was observed in PM. Results suggested that LL and PM might be healthful because of higher desirable fatty acid value and PUFA/SFA ratio, respectively. Also, data showed that correlations between muscle fiber types and fatty acids proportion of goat muscles were reversed with those of cattle muscles.

• Animal Bioscience
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• v.36 no.2_spc
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• pp.374-384
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• 2023

Skeletal muscle metabolism regulates homeostatic balance in animals. The metabolic impact persists even after farm animal skeletal muscle is converted to edible meat through postmortem rigor mortis and aging. Muscle metabolites resulting from animal growth and postmortem storage have a significant impact on meat quality, including flavor and color. Metabolomics studies of postmortem muscle aging have identified metabolisms that contain signatures inherent to muscle properties and the altered metabolites by physiological adaptation, with glycolysis as the pivotal metabolism in postmortem aging. Metabolomics has also played a role in mining relevant postmortem metabolisms and pathways, such as the citrate cycle and mitochondrial metabolism. This leads to a deeper understanding of the mechanisms underlying the generation of key compounds that are associated with meat quality. Genetic background, feeding strategy, and muscle type primarily determine skeletal muscle properties in live animals and affect post-mortem muscle metabolism. With comprehensive metabolite detection, metabolomics is also beneficial for exploring biomarker candidates that could be useful to monitor meat production and predict the quality traits. The present review focuses on advances in farm animal muscle metabolomics, especially postmortem muscle metabolism associated with genetic factors and muscle type.