Omics research has indicated that heat shock protein 70 (HSP70) is a potential biomarker of meat quality. However, the specific changes and the potential role of HSP70 in postmortem meat quality development need to be further defined. In this study, Arbor Acres broiler chickens (n = 126) were randomly categorized into three treatment groups of unstressed control (C), 0.5-h transport (T) and subsequent water shower spray following transport (T/W). Each treatment consisted of six replicates with seven birds each. The birds were transported according to a designed protocol. The pectoralis major (PM) muscles of the transport-stressed broilers were categorized as normal and pale, soft and exudative (PSE)-like muscle samples according to L* and pH 24 h values to test the expression and location of HSP70. Results revealed that the activities of plasma creatine kinase and lactate dehydrogenase increased significantly ( P < 0.05) in normal and PSE-like muscle samples after transportation. The mRNA expression of HSP70 in normal muscle samples increased significantly ( P < 0.05) compared with that in the controls after stress. The protein expression of HSP70 increased significantly in normal muscle samples and decreased significantly ( P < 0.05) in PSE-like muscles. Immuno-fluorescence showed that HSP70 was present in the cytoplasm and on surface membranes of PM muscle cells in the normal samples following stress. Meanwhile, HSP70 was present on the surface membranes and extracellular matrix but was barely visible in the cytoplasm of the PSE-like samples. Principal component analysis showed high correlations between HSP70 and meat quality and stress indicators. In conclusion, this research suggests that the variation in HSP70 expression may provide a novel insight into the pathways underlying meat quality development.

Lactobacillus rhamnosus strain ASCC 1520 with high soy isoflavone transformation ability was used to ferment soymilk and added to the diet of mice. The impact of L. rhamnosus fermentation on soy isoflavone metabolites and intestinal bacterial community, in conjunction with fecal enzyme activity and short‐chain fatty acids (SCFA) excretion was evaluated. Antibiotics intervention resulted in a decrease in fecal enzyme activities and SCFA. Although long‐term intake of soymilk or L. rhamnosus‐fermented soymilk did not affect the fecal β‐glucuronidase and β‐galactosidase activities, it improved the β‐glucosidase activity when antibiotics were concomitantly administered. Soymilk or fermented soymilk administration increased the isoflavone metabolites (O‐DMA and equol) excreted in urine. Antibiotics decreased the daidzein excretion and its metabolites but showed little effect on glycitein and genistein excretion. Principal coordinates analysis (PCoA) of the 16s rRNA gene sequencing data found a remarkable shift in gut microbiota after soymilk administration and antibiotics treatment. Matastats test of the relative abundance of bacterial taxa revealed Odoribacter (Bacteroidales family), Lactobacillus (Lactobacillales order), and Alistipes (Rikenellaceae family) were enriched in soymilk while bacterial taxa from Bacteroides and Lactobacillus were enriched in L. rhamnosus‐fermented soymilk. Furthermore, there was less decrease in bacterial taxa with fermented soymilk group even when antibiotics were concomitantly administered. Overall, this study revealed that the gut microbiota of a healthy host is enough for the whole isoflavone metabolism under normal conditions. Feeding mice with L. rhamnosus‐fermented soymilk improved fecal enzyme activity and kept the balance of the gut mirobiota when antibiotics were used. Practical Application Feeding mice with L. rhamnosus‐fermented soymilk improved fecal enzyme activity and kept the balance of the gut mirobiota when antibiotics were used.