Changes of Raw Texture, Intramuscular Connective Tissue Properties and Collagen Profiles in Broiler Wooden Breast during Early Storage

Spatial transcriptomic differences in the breast muscle of grower broilers at 21 and 28 days of age

This study investigated transcriptomic differences between the caudal and cranial areas in breast muscle in the grower phase of broiler chickens (D 21 and D 28). A total of 66 one-day-old broiler chickens were allotted to 6 cage pens of 11 birds per pen. On D 21 and D 28, one bird per pen was randomly selected, and breast muscle samples were collected in the caudal and cranial areas of the Pectoralis major. RNA sequencing was conducted, followed by screening for differentially expressed genes (DEGs; P < 0.05) and multivariate analyses. A total of 24,498 genes were identified, and 8,831 genes had greater than 100 mean read count. On D 21, there were 666 DEGs, among which 482 and 184 genes were down-regulated and up-regulated, respectively, in the caudal area compared with the cranial area. There were 2 down-regulated and 56 up-regulated genes with a greater than 1.5-fold change (FC). On D 28, there were 872 DEGs, among which 408 and 464 genes were down-regulated and up-regulated, respectively. There were 12 down-regulated and 23 up-regulated genes with a greater than 1.5-fold change. Principal component analysis (PCA) plots showed that gene profiles were not distinctly separated between the caudal area and the cranial area of breast muscle on D 21 and D 28. On D 21, collagen type XI alpha 1 chain (COL11A1), fibromodulin (FMOD), myosin heavy chain 7B (MYH7B), carbonic anhydrase 3A (CA3A), tenomodulin (TNMD), COL12A1, carboxypeptidase Z (CPZ), lysyl oxidase like 2 (LOXL2), COL1A1, and COL1A2 were significantly down-regulated in the caudal area compared to the cranial area with a greater than 2-FC (P < 0.05). KEGG pathway enrichment analysis indicated that various pathways including regulation of actin cytoskeleton, ribosome, and focal adhesion were significantly different in the caudal area compared with the cranial area. These findings suggest that spatial differences in gene expression within the breast muscle could be linked to functional or developmental variations between regions, potentially influencing muscle growth, meat quality, and breast myopathies. Understanding these spatial transcriptomic differences may provide insights into identifying etiologies and developing strategies for breast myopathies.

Research Note: Relationships between texture and water property measurements in raw intact broiler breast fillets with the wooden breast condition

Relationships between texture measurements and meat water properties were investigated in raw intact broiler breast fillets with the wooden breast (WB) condition. Texture measurements included subjective WB scores and blunt Meullenet-Owens Razor Shear (BMORS). Water properties were determined with low-field nuclear magnetic resonance (LF-NMR). Spearman correlation was used to estimate relationships between WB scores and water properties, while Pearson correlation was used for relationships between BMORS force and water properties. LF-NMR measurements exhibited 3 water components: protein-associated or hydration water T2b, intra-myofibrillar water or immobilized water T21, and extra-myofibrillar water or free water T22 in chicken breast meat. Significant and strong Spearman correlations were found between the WB scores and T21 time constant, the abundance (normalized areas) of T22, and the proportion of T21 and T22 (rs > 0.60, P < 0.001). Strong Pearson correlations (r = 0.72) were noted only between the T21 time constant and BMORS force. These results demonstrate that water may contribute to the specific texture characteristics measured with subjective WB scoring (palpable hardness and rigidity) and BMORS (hardness and share force) in raw broiler breast fillets with the WB condition.

Relationships of quality indices with wooden breast myopathy severity in chicken breast meat under refrigerated storage

1. This study investigated the relationships of quality indices with the severity of wooden breast (WB) myopathy in chicken breast meat under refrigerated storage. The physicochemical properties, water-holding capacity (WHC), microbial quality and fatty acid profiles of normal chicken breast meat samples (NOR samples, n = 63), moderate WB (MWB, n = 63) myopathy and severe WB (SWB, n = 63) myopathy (MWB and SWB samples, respectively) were evaluated immediately after sampling and after 4 and 8 d of refrigerated storage at 4°C.2. Total collagen, fat, saturated and monounsaturated fatty acid contents, redness and pH of the SWB and MWB samples were higher than the NOR samples. The SWB samples that were stored for 8 d had poor WHC, total viable counts (TVC) of higher than 7.0log colony-forming units, total volatile basic nitrogen (TVB-N) content of greater than 15 mg/100 g and a thiobarbituric acid - reactive substance level of higher than 1 mg/kg malondialdehyde.3. No significant difference was observed in the TVB-N content and TVC of the MWB and NOR samples during storage. Polyunsaturated fatty acid content was lower in the SWB and MWB samples than in the NOR samples. The SWB samples were tougher than the MWB and NOR samples after 8 d of refrigeration.4. In conclusion, the quality of chicken breast meat with SWB myopathy degraded considerably over time; thus, such meat should not be subjected to extended refrigeration for storage.