The aim of this study was to determine the relationships among muscle fiber‐type composition, fiber diameter, and myogenic regulatory factor (MRF) gene expression in different skeletal muscles during development in naturally grazing Wuzhumuqin sheep. Three major muscles (i.e. the Longissimus dorsi (LD), Biceps femoris (BF) and Triceps brachii (TB)) were obtained from 20 Wuzhumuqin sheep and 20 castrated rams at each of the following ages: 1, 3, 6, 9, 12 and 18 months. Muscle fiber‐type composition and fiber diameter were measured using histochemistry and morphological analysis, and MRF gene expression levels were determined using real‐time PCR. In the LD muscle, changes in the proportion of each of different types of fiber (I, IIA and IIB) were relatively small. In the BF muscle, a higher proportion of type I and a 6.19‐fold lower proportion of type IIA fibers were observed (P < 0.05). In addition, the compositions of type I and IIA fibers continuously changed in the TB muscle (P < 0.05). Moreover, muscle diameter gradually increased throughout development (P < 0.05). Almost no significant difference was found in MRF gene expression patterns, which appeared to be relatively stable. These results suggest that changes in fiber‐type composition and increases in fiber size may be mutually interacting processes during muscle development.

MicroRNAs (miRNAs) are regarded as important regulators in skeletal muscle development. To reveal the regulatory roles of miRNAs and their target mRNAs underlying the skeletal muscle development of Wuranke sheep, we investigated the miRNA and mRNA expression profiles in the biceps femoris of these sheep at the fetal (3 months of gestation) and 3- and 15-month-old postnatal stages. Consequently, a total of 1195 miRNAs and 24,959 genes were identified. Furthermore, 474, 461, and 54 differentially expressed miRNAs (DEMs) and 6783, 7407, and 78 differentially expressed genes (DEGs) were detected among three comparative groups. Functional analysis demonstrated that the target mRNAs of the DEMs were enriched in multiple pathways related to muscle development. Moreover, the interactions among several predicted miRNA–mRNA pairs (oar-miR-133-HDAC1, oar-miR-1185-5p-MYH1/HADHA/OXCT1, and PC-5p-3703_578-INSR/ACTG1) that potentially affect skeletal muscle development were verified using dual-luciferase reporter assays. In this study, we identified the miRNA and mRNA differences in the skeletal muscle of Wuranke sheep at different developmental stages and revealed that a series of candidate miRNA–mRNA pairs may act as modulators of muscle development. These results will contribute to future studies on the function of miRNAs and their target mRNAs during skeletal muscle development in Wuranke sheep.

We investigated the effect of combined high pressure and sodium hydrogen carbonate (NaHCO₃) treatment on the physical properties and color of silverside Australian beef. Meat samples were pressurized at 100–500 MPa and the water content, weight reduction, rupture stress, and meat color were determined. The water content of meat treated with NaHCO₃ and high pressure (300 MPa) reached a maximum of 70.1%. Weight reduction tended to decrease with high pressure treatment at 300 MPa. Meats treated with NaHCO₃ and high pressure at 400 MPa showed a>50% decrease in hardness. Whitening of the meat was reduced by the combined high pressure and NaHCO₃ treatment. Therefore, the combined high pressure and NaHCO₃ treatment is effective for improvement of beef quality.

In this study, the combined effects of high pressure and sodium hydrogen carbonate (NaHCO₃) treatment on the physical and chemical properties, and palatability of pork ham, a tough and under-utilized meat, were investigated. Assessment of meat properties with heat treatment, after exposure to NaHCO₃ and high pressure treatment, revealed an increase in water content, and decreased weight reduction and rupture stress. The free amino acid content of meat samples increased with NaHCO₃ and high pressure treatment. The effect of high pressure processing was especially notable at a pressure of 300 MPa. Sensory evaluation showed that meat subjected to high pressure processing after NaHCO₃ treatment was tender and juicy. In addition, the sample produced minimal residue in the mouth and was characterized by a good taste.

Chicken breast is not preferred in Japan because it is not juicy. In this study, the effect of combined high pressure and sodium hydrogen carbonate (NaHCO₃) treatment on the texture and palatability of chicken breast was investigated. The sample used was broiler chicken breast. Meat samples were soaked in.0–.4 M NaHCO₃ solution and then pressurized at 100–400 MPa. After pressurization, the samples were heated for 30 min at 80°C and cooled down in ice-cold water. High pressure and NaHCO₃ treatment of broiler chicken breast resulted in increased water content, and decreased weight reduction and rupture stress. Moreover, meat exposed to 200 MPa pressurization and.3 M NaHCO₃ treatment was judged tender, juicy and of good taste by sensory evaluation. The combination of high pressure and NaHCO₃ treatment can be effectively used for broiler chicken breast production.

Changes in the localization of calpain in conditioned and pressurized bovine skeletal muscles were investigated by immunogold electron-microscopy. In the muscle immediately after thawing (control), the relative distributions of colloidal particles statistically calculated by counting the colloidal particles were about 65% and 35% in the I-band/Z-disk and A-band regions, respectively. In the muscle conditioned for 7 days, distribution of colloidal particles was more than two times greater in both the I-band/Z-disk and A-band regions than in the control muscle. Almost no change in either the absolute concentration or relative distribution of the colloidal particles was detectable during further storage. In the muscle exposed to a pressure of 100 MPa or 200 MPa, slightly more immunogold was detected in the sarcomere than in that of the control muscle. Increasing pressure up to 300 MPa enabled high-density particles to be seen throughout the sarcomere. Conversely, few particles were detected in the sarcomere of the muscle exposed to 400 MPa. These electron-microscopic observations were confirmed from the statistical analysis as with the conditioned muscles. It was clear from the results obtained that the pressure-induced changes in calpain localization were much more pronounced than those from conditioning.