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Highlights • Long-term physical exercise before slaughter resulted in faster muscle pH decline post-mortem and more yellow meat in Sunit sheep. • Physical exercise caused a shift of muscle fibers from oxidative to glycolytic type. • Physical exercise activated skeletal muscle satellite cells influencing the process of conversion from muscle to meat. Abstract The objective of this study was to investigate the effects of muscle exercise on meat quality characteristics and protein and gene expression of Sunit sheep. To this end, 24 Sunit sheep that had the same genetic background and had been raised on extensive pasture for their first 9 months were randomly divided into two groups (12 sheep each), which were raised separately for 3 months until slaughter. The first group of sheep was kept on pasture and allowed to move freely outdoors (M Group), whereas the other group of sheep was kept in one pen on the farm (control [C] group). After slaughter, samples of the longissimus dorsi muscle were taken to evaluate meat quality. The differences in the expression of muscle-exercise-related proteins and genes between the two groups were analyzed by Western blotting and RT-PCR techniques. The results showed reductions in the pH measured 1 h and 24 h post-mortem and in the a* value (redness) for meat colour in the longissimus dorsi muscle of the sheep in the M group in comparison with those in the C group (P < 0.01), while an increasing b* value (yellowness) for meat colour was observed in the M group sheep (P < 0.01). The greater (P < 0.05) levels of Pax7 and MyoD but not PPARγ in the M group indicated that the activated skeletal muscle satellite cells underwent myogenesis rather than adipogenesis. In addition, endurance exercise caused a shift in myosin heavy chain composition from the oxidative isoform to the glycolytic form (P < 0.01), which may have resulted in the pH decline and the colour change. In conclusion, exercise-induced activation of skeletal muscle satellite cells, which regulate the pH and colour of meat, was associated with the transformation of muscle fiber types in Sunit sheep. [ABSTRACT FROM AUTHOR]

Highlights • Feeding regimens effected gene expression of FADS1 and FADS2 in adipose tissue. • The content of n-3 PUFA, especially EPA and DHA is higher in pastured sheep. • Different tissues have variable sensibilities to feeding regimens. Abstract The present study investigated the effects of two feeding regimens on meat quality, fatty acid profile and metabolism as it relates to gene expression in Sunit sheep. Two feeding regimens were used (pasture feeding and barn feeding, PF and BF) each containing 10 Sunit sheep. Results of this study indicated that PF sheep had significantly (P < 0.05) higher L* and b* values in their muscle compared to BF sheep. Also, the fatty acid composition of longissimus dorsi muscle and subcutaneous adipose tissues differed between feeding regimens. In this respect, concentrations of palmitic acid (C16:0) in the subcutaneous adipose tissue were significantly (P < 0.05) higher in BF sheep. Pastured sheep exhibited greater concentrations of polyunsaturated fatty acids (PUFA) including: linolenic acid (C18:3) (P < 0.001), DHA (P < 0.05), EPA (P < 0.001) and CLA cis-9, trans-11(P < 0.05) in their muscle compared to BF sheep. The expression of nine candidate genes related to fatty acid metabolism were analyzed by qPCR. In longissimus dorsi muscle, expression of acetyl CoA carboxylase (ACACA; P < 0.05) was up-regulated in BF sheep. Expression of the peroxisome proliferator activated receptor (PPARγ) (P < 0.05), stearoyl CoA desaturase (SCD) (P < 0.01), fatty acid desaturase1 (FADS1) (P < 0.05) and fatty acid desaturase 2 (FADS2) (P < 0.05) were up-regulated in PF sheep. Pasture feeding also increased (P < 0.05) expression of lipoprotein lipase (LPL), PPARγ, SCD, FADS1and fatty acid elongase 5 (Elove5) in the subcutaneous adipose tissue, however, the feeding regimens did not change expression of fatty acid synthase (FASN) and carnitine palmitoyl transferase I (CPT1). The results of this study indicated that the feeding regimen could be an important tool in manipulating the fatty acid profile of animal adipose tissue by altering the gene expression of enzymes involved in fat metabolism. [ABSTRACT FROM AUTHOR]

• The chilled aging time was closely related to the lipid content and species. • GP and FA were the main differential lipid classes during chilled aging. • 48 h of postmortem chilled aging was the turning point for lipid transformation. • Hydrolase activity and oxidation degree might be responsible for lipid changes. • Glycerophospholipid metabolism and thermogenesis are the major aging pathways. This present study aimed to investigate the effects of postmortem chilled aging on lipid and molecular transformation mechanisms in Mongolian sheep. UPLC-ESI-MS/MS was used to identify 812 lipids in Mongolian sheep within four days of chilled aging. Using multivariate analysis, 95 significant differential lipids were identified. The levels of phosphatidylcholine, phosphatidylinositol, and certain free fatty acids were observed to rise significantly, while other phospholipids and acylcarnitines showed a downward trend. In addition, levels of most of the lysophospholipids increased significantly in the early postmortem period; however, their levels did not alter significantly after 48 h. The Kyoto encyclopedia of genes and genomes pathway analysis revealed that these differential lipids are primarily involved in glycerophospholipid metabolism, linoleic acid metabolism, arachidonic acid metabolism, and thermogenesis. Our results have important implications in terms of understanding lipid transformation and changes in meat quality during postmortem chilled aging in Mongolian sheep. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the effects of muscle exercise on meat quality characteristics and protein and gene expression of Sunit sheep. To this end, 24 Sunit sheep that had the same genetic background and had been raised on extensive pasture for their first 9 months were randomly divided into two groups (12 sheep each), which were raised separately for 3 months until slaughter. The first group of sheep was kept on pasture and allowed to move freely outdoors (M Group), whereas the other group of sheep was kept in one pen on the farm (control [C] group). After slaughter, samples of the longissimus thoracis muscle were taken to evaluate meat quality. The differences in the expression of muscle-exercise-related proteins and genes between the two groups were analyzed by Western blotting and RT-PCR techniques. The results showed reductions in the pH measured 1 h and 24 h post-mortem and in the a* value (redness) for meat colour in the longissimus thoracis muscle of the sheep in the M group in comparison with those in the C group (P < 0.01), while an increasing b* value (yellowness) for meat colour was observed in the M group sheep (P < 0.01). The greater (P < 0.05) levels of Pax7 and MyoD but not PPARγ in the M group indicated that the activated skeletal muscle satellite cells underwent myogenesis rather than adipogenesis. In addition, endurance exercise caused a shift in myosin heavy chain composition from the oxidative isoform to the glycolytic form (P < 0.01), which may have resulted in the pH decline and the colour change. In conclusion, exercise-induced activation of skeletal muscle satellite cells, which regulate the pH and colour of meat, was associated with the transformation of muscle fiber types in Sunit sheep. [ABSTRACT FROM AUTHOR]