The quality of pasteurized milk is commonly assessed through microbiological analysis, with variations in storage conditions significantly impacting the suppression of bacterial growth throughout the milk’s shelf life. This study investigated the dynamics of total bacterial counts (TBCs) and bacterial community shifts in milk that underwent pasteurization at 80 °C for 15 s. The milk was subsequently stored at 4 °C for varying intervals of 1, 4, 7, 10, 13, and 16 days. Culture-based testing revealed a significant TBC increase during the storage period spanning 1 to 16 days (up to −log10 4.2 CFU/mL at day 16). The TBC in pasteurized milk exhibited accelerated microbial growth from day 13 onwards, ultimately peaking on day 16. Bacillus was detected through 16S rRNA identification. Principal component analysis demonstrated a significant impact of storage time on bacterial communities in pasteurized milk. Analysis of bacterial diversity revealed a negative correlation between the Shannon index and the duration of pasteurized milk storage. Using high-throughput sequencing, Streptococcus and Acinetobacter were detected as prevalent bacterial genera, with Streptococcus dysgalactiae and Streptococcus uberis showing as dominant taxa. The presence of Streptococcus dysgalactiae and Streptococcus uberis in pasteurized milk might be attributed to the initial contamination from raw milk with mastitis. This study offers new evidence of the prevalence of bacterial community in pasteurized milk, thereby adding value to the enhancement of quality control and the development of strategies for reducing microbial risks.

Sialic acid (N‐acetylneuraminic acid), a 9‐carbon monosaccharide, has been widely studied in immunology, oncology, and neurology. However, the effects of sialic acid on organ and intestinal development, liver function and gut microbiota were rarely studied. In this study, we found that oral sialic acid tended to increase the relative weight of liver and decreased the serum aspartate aminotransferase (GPT) activity. In addition, sialic acid treatment markedly reduced gut villus length, depth, the ratio of villus length/depth (L/D), areas, width, and the number of goblet cells. Furthermore, gut microbes were changed in response to oral oral sialic acid, such as Staphylococcus lentus, Corynebacterium stationis, Corynebacterium urealyticum, Jeotgalibaca sp_PTS2502, Ignatzschineria indica, Sporosarcina pasteurii, Sporosarcina sp_HW10C2, Facklamia tabacinasalis, Oblitimonas alkaliphila, Erysipelatoclostridium ramosum, Blautia sp_YL58, Bacteroids thetaiotaomicron, Morganella morganii, Clostridioides difficile, Helicobacter tryphlonius, Clostridium sp_Clone47, Alistipes finegoldii, [pseudomonas]_geniculata and Pseudomonas parafulva at the species level. In conclusion, oral sialic acid altered the intestinal pathological state and microbial compositions, and the effect of sialic acid on host health should be further studied.

This study investigated whether rosemary extract (RE) supplementation selectively reshapes ruminal butyrate-producing microbiota and enhances functional milk properties in lactating dairy goats. Twenty-four goats were fed a control diet or a diet supplemented with 2.14 g/kg RE (n = 12) during a 42-day feeding trial. Rumen fermentation parameters, bacterial community composition, and milk quality indices - including bioactive proteins, amino acid and fatty acid profiles, and somatic cell count - were analyzed. RE supplementation significantly increased butyrate concentration and tended to elevate valeric acid. The relative abundances of fibrolytic bacteria (Ruminococcus albus and Fibrobacter succinogenes) and butyrate-producing taxa (i.e., Butyrivibrio) were significantly enriched (p < 0.05) in the RE group. Notably, dietary RE markedly elevated milk bioactive proteins, including lactoferrin, α-lactalbumin, and β-lactoglobulin (p < 0.05), and reduced somatic cell count (p < 0.05). These findings reveal a microbiota-mediated pathway through which RE enhances the functional quality of goat milk and support the potential of phytogenic feed additives.