To evaluate the effects of probiotic-fermented feed (PBF) on heat-stressed dairy cows.

36 healthy mid-lactation Holstein cows were selected from a dairy farm in Tengzhou and randomly divided into three groups (n = 12 each): control (CON, basal diet), low-dose (L-PBF, 2% fermented feed), and high-dose (H-PBF, 4% fermented feed). The trial lasted 56 days, including a 14-day adaptation period and a 42-day treatment period. Dry matter intake (DMI) and milk yield were recorded, and milk samples were collected for composition analysis. Blood samples were collected on days 0, 21, and 42 to measure serum cortisol (CORT), heat shock protein 70 (HSP70), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-10 (IL-10). Fecal samples were collected on days 0 and 42 for qPCR quantification of Lactobacillus, Bifidobacterium, and Escherichia coli.

Results showed that 4% PBF significantly increased the abundance of Lactobacillus and Bifidobacterium while reducing E. coli in rectal feces (P < 0.05). It also significantly decreased serum levels of CORT, HSP70, TNF-α, and IL-6, while increasing IL-10 (P < 0.05). Additionally, 4% PBF significantly improved DMI, milk yield, milk fat percentage, and milk protein percentage (P< 0.05).

Appropriate supplementation of PBF can improve intestinal microecology and internal homeostasis in heat-stressed dairy cows, thereby enhancing productive performance.

To reduce the use of veterinary antibiotics, explore the in vitro synergistic antibacterial effect of the combination of traditional Chinese medicine compound and cephalosporin antibiotics on multi-drug resistant Staphylococcus aureus (MRSA) in dairy cows with mastitis, and screen combined medication regimens that enhance efficacy and reduce toxicity.

In this study, MRSA strains were isolated and identified from the breast secretions of clinically affected dairy cows. The minimum inhibitory concentrations (MIC) of a traditional Chinese medicine compound (consisting of six traditional Chinese medicines such as dandelion, honeysuckle, and forsythia) and two cephalosporin antibiotics, ceftiofur and cefquinome, were determined by the micro-broth dilution method. The synergistic antibacterial index (FICI) of the combined medication was detected by the checkerboard dilution method, and the effects of different drug combinations on the MRSA growth curve were observed.

The individual MIC of the isolated MRSA strains for ceftiofur and cefquinome were 64, 32μg/mL respectively, and the individual MIC of the traditional Chinese medicine compound was 256 mg/mL. The FICI of the combination of the traditional Chinese medicine compound with ceftiofur and cefquinome was 0.38 and 0.25 respectively, both showing significant synergistic antibacterial effects. The inhibitory effect of the combined medication group on the growth of MRSA was stronger than that of the single medication group, which could shorten the onset time of the antibacterial effect and prolong the duration of the antibacterial effect.

The combination of traditional Chinese medicine compound and cephalosporin antibiotics can significantly reduce the inhibitory concentration of the latter against MRSA, enhance the inhibitory effect, and decrease the clinical dosage of cephalosporin antibiotics. This provides a new medication idea and experimental basis for the treatment of drug-resistant strain infections in dairy cow mastitis.

To investigate the composition of psychrotrophic bacterial communities and the diversity of psychrotrophic microorganisms in dairy raw materials from different pastures and at different production times.

36 raw milk samples were collected from large-scale pastures in North China. To investigate the alterations in bacterial community composition and the variety of psychrotrophic bacteria in raw milk from various pastures and seasons, researchers employed both 16SrRNA sequencing and conventional isolation and culture techniques.

From the 36 samples, psychrotrophic bacteria were obtained and classified through conventional culturing techniques, identifying 474 species across 23 genera. At the genus level, the proportions were in the order of Pseudomonas, Acinetobacter, Flavobacterium, Rheinheimera, Psychrobacter, and Enterobacter. The concentration of psychrotrophic bacteria ranged from 1.71 to 3.78 lgCFU/mL, with an average concentration of 2.79 lgCFU/mL. Analysis of the 36 samples using 16SrRNA amplicon sequencing annotated a total of 37 phyla, 90 classes, 214 orders, 358 families, 740 genera and 12 301 species. The top 10 dominant genera in terms of microbial diversity abundance were Acinetobacter, Escherichia, Delftia acidovorans, Aeromonas, Pseudomonas, UCG-005, Streptococcus, Faecalibacterium, Corynebacterium and Flavobacterium.

Substantial variations were observed in the levels of psychrotrophic bacteria, the structure of psychrotrophic bacterial communities and the diversity of psychrotrophic microorganisms in raw milk sourced from various pastures and at various times. This research lays the groundwork for theoretical investigations into the microbial variety of psychrotrophic bacteria found in raw milk in Northern China and supplies data assistance for farms in the area to develop tailored strategies for managing and preventing psychrotrophic bacteria.

To study the effects of different storage conditions on the microbial and physicochemical properties of pasteurized milk.

Pasteurized milk was stored at 2, 7, 10, 15, 25 and 35 ℃ for 0~72 h respectively, and the changes in microbial count, pH value and acidity were measured regularly.

With the extension of storage time and the increase of temperature, the total bacterial count, the number of lactic acid bacteria, and the number of coliform bacteria in pasteurized milk all increased significantly (P<0.05). In pasteurized milk stored at 7 ℃, the microbial growth was slow, and the total bacterial count remained within the safe range at 72 h; when stored at 15 ℃, the microbial growth rate accelerated, and the total bacterial count exceeded the national standard limit after 36 h; when stored at 25 ℃ and 35 ℃, the microorganisms proliferated rapidly, far exceeding the national standard limit. The pH value of pasteurized milk gradually decreased with the extension of storage time and the increase of temperature, while the acidity gradually increased. The changing trends of both were closely related to the growth of microorganisms.

Refrigeration at 7 ℃ could effectively inhibit the growth of microorganisms in pasteurized milk and extend its shelf-life. When storing pasteurized milk at room temperature, it should be consumed as soon as possible to avoid quality deterioration caused by excessive microbial growth.

Hand-torn cheese is a snack-like cheese developed based on the production process of mozzarella cheese. This research aimed to investigate the effects of various process conditions and parameters on the yield, sensory quality, texture characteristics, fat and protein contents of the finished hand-torn cheese, in order to obtain the optimal process parameters.

By adjusting the acidity (acidification at 10 ℃ and 37 ℃), regulating the acidification pH value (4.5, 5.0, 5.5, 6.0), setting different boiling temperatures (70, 80, 90 ℃) and different stretching folding times (50, 75, 100, 125 times), the effects of the above process parameters on the yield, sensory quality, fat and protein contents of the finished hand-torn cheese were analyzed.

The hand-torn cheese produced by the low-temperature acidification method had higher fat and protein contents, a relatively higher yield and moderate softness, and finer silkiness; when the pH value was 5.5 or 6.0, curdling and stretching could be successfully achieved; when the pH value was 6.0, the yield, fat and protein contents of the hand-torn cheese were higher than those when the pH value was 5.5, and the overall sensory quality, especially the silkiness and chewing sensation, was weaker than that when the pH value was 5.5; during the boiling process, as the boiling temperature increased, the total yield and the fat content of the finished hand-torn cheese showed a downward trend, while the protein content showed an upward trend; with the increase in stretching folding times, the total yield and the fat content of the finished hand-torn cheese showed a downward trend, while the protein content showed an upward trend. When the stretching folding times were 75, the overall tissue characteristics, silkiness and elasticity scores were relatively higher.

The optimal process parameters for hand-torn cheese were: using the low-temperature acidification process, with an acidification pH value of 5.5, a boiling temperature of 80 ℃ and a stretching folding time of approximately 75 times. This process resulted in a higher yield of product, and the hand-torn cheese produced had better sensory quality and texture characteristics.

To explore the correlation between various physicochemical and microbiological indicators in raw milk and the activity of protease.

Taking raw milk from different regions as samples, the protease activity was determined using the Folin phenol method, and the effects of season and the composition raw milk (fat, protein, lactose, total solids, total bacterial count, somatic cell count) on the protease activity was analyzed accordingly.

The effects of seasonal factors on protease activity: The enzyme activity was generally higher in winter than in summer, and a certain pastures in Ningxia showed a more obvious seasonal variation trend. The effect of raw milk components on protease activity: Among the physicochemical indicators, protein and fat content were significantly correlated with protease activity, while the changes in lactose content has no significant effect on enzyme activity; in terms of microbial indicators, the number of psychrophilic bacteria had a stronger explanatory power for the change in protease activity. In high-quality raw milk, the correlation between the somatic cell count and total bacterial count and protease activity was relatively weak.

The protease activity in raw milk is significantly affected by factors such as seasonal temperature changes, changes in protein content, and the composition of the dominant enzyme producing bacterial population. In-depth study of these factors is of great significance for the assessment of raw milk quality and the improvement of product quality.

In the quality control system of the dairy industry, non-destructive testing technology for sterilized milk has gained increasing attention due to its advantages of low cost and high efficiency. This study focuses on the accuracy of test results of sterilized milk stored at different temperatures when detected under the same temperature calibration module of the RS-6 dairy package shaker.

A certain quantity of sterilized milk was incubated at different temperatures (5, 10, 15, 20, 25, 30, 35, and 40 ℃) and tested using the shaking module calibrated at 20, 25, and 30 ℃, respectively.

The experimental results showed that when the temperature difference between the calibration sample during calibration and the tested sample was within ± 5 ℃, the accuracy of the detection results from the shaker was the highest, with a pass rate of 100%. However, when the temperature difference exceeded 5 ℃, the detection pass rate significantly decreased as the temperature difference increased.

This research finding holds significant practical importance for optimizing the quality control process of sterilized milk. It can provide dairy enterprises with a more precise and efficient testing method, thereby contributing to the overall improvement of quality management standards in the industry.