In order to clarify and understand the immune mechanism of sheep mammary gland,this paper introduces the main tissues and immune substances involved in the immune defense of mammary gland,including breast papilla,mammary epithelial cells,white blood cells,immunoglobulin,complement system and chemical antibacterial agents,and describes the cooperation and interaction between them.The nipple of the breast papilla provides the initial protection for the breast.Mammary epithelial cells synthesize antibacterial proteins and white blood cells produce various inflammatory mediators（cytokines or chemokines）,engulf bacteria and recognize antigenic structures.In the mammary gland,four immunoglobulins（IgG1,IgG2,IgM and IgA） play an important role in combating bacterial pathogens.The complement system is a collection of proteins that participate in the inflammatory process through a variety of ways.Chemical antibacterial agents such as lactoferrin,lysozyme and lactoperoxidase contribute to the defense of breast fluid.

Heat stress is a critical factor constraining economic efficiency in animal husbandry,particularly in the high-temperature and high-humidity environments of southern regions,where its adverse effects on dairy cow performance,milk yield,reproductive efficiency,and immune function are especially pronounced.Notably,the peak period of heat stress from July to September coincides with a surge in calving numbers,attributable to concentrated breeding activities following the previous year's heat stress period（October-December）and accumulated pregnancies due to reduced conception rates during heat stress. In this context,postpartum uterine care is essential for farm management：（1）it promotes uterine involution,restoring reproductive function and safeguarding fertility potential.（2）it reduces the incidence of retained fetal membranes,metritis,and other disorders,minimizing reproductive failures and production losses.（3）it optimizes reproductive efficiency,ensuring normal estrus-breeding-conception cycles. The dual stressors of heat and parturition further exacerbate uterine health risks,necessitating targeted involution management. From an economic perspective,scientific uterine care not only lowers treatment costs but also significantly enhances farm profitability by improving reproductive performance.

[Objective] To investigate the effects of compound Chinese herbal additives on lactation performance and milk composition of dairy goats. [Method] 40 healthy and disease-free dairy goats of 2 years old with similar parity were selected and randomly divided into 4 groups,which were set as the control group,the low-dose compound Chinese herbal medicine group,the medium-dose compound Chinese herbal medicine group and the high-dose compound Chinese herbal medicine group. There were 2 replicates in each group,and 5 goats in each replicate.The basic diet+0 g/（d·goat）,basic diet+10 g/（d·goat） and basic diet+15 g/（d· animal） of the compound Chinese herbal medicine additives were respectively fed, and the experiment lasted for 30 days. [Result] With the increase of the addition dosage of compound Chinese herbal medicines,the feed intake and milk-to-feed ratio of dairy goats tended to increase（P>0.05）.Compared with the control group,the milk production of dairy goats in the medium-dose and high-dose compound Chinese herbal medicine groups increased significantly（P<0.05）,increasing by 6.86% and 8.73%,respectively. Compared with the control group,the milk fat rate and milk protein rate of medium-dose and high-dose compound Chinese herbal medicine groups were significantly increased（P<0.05）,increasing by 4.09%,5.18% and 3.35%,4.83% respectively. The lactose rate and dry milk matter of dairy goat milk in each experimental group showed an increasing trend（P>0.05）. [Conclusion] Adding compound Chinese herbal additives to the diets could effectively improve the lactation performance of dairy goats and the quality of milk components,and under the conditions of this experiment,the best effect was achieved when the addition dose of compound Chinese herbal was 15 g/（d·goat）.

In order to study the serotyping,phylogenetic clustering and virulence gene distribution of Escherichia coli isolated from dairy cow manure with diarrhea in dairy cows,147 fresh feces of dairy cows with diarrhea symptoms were collected from some dairy farms in Shandong Province.The isolated strain was confirmed to be pathogenic Escherichia coli by routine bacterial isolation and culture,biochemical test and PCR amplification of bacterial 16S rDNA molecular biology technology.The serotype,phylogenetic clustering and virulence gene of the isolated strain were further detected,and the distribution of virulence gene in the phylogenetic clustering was analyzed.The results showed that 62 strains of Escherichia coli were identified and 9 pathogenic serotypes were identified.Among them,intestinal invasion（EIEC）,intestinal pathogenicity（EPEC）,and enterotoxigenic（ETEC） E.coli serotypes accounted for 17.74%,24.19%,and 19.35%,respectively.The dominant serotyping were O125∶K70（B15） and O124∶K72.18 strains belonged to group A,12 strains belonged to group B1,15 strains belonged to group B2,9 strains belonged to group D,and 8 strains could not determine the phylogenetic clustering.The distribution rates of virulence genes ibeB,mat and fimC were high,which were 100.00%,95.16% and 91.94%,respectively.At least 4 virulence gene and 9 virulence gene combinations were distributed in all strains.The correlation analysis between virulence gene and phylogenetic clustering showed that the distribution rate of ibeB in the four groups was 100%,and 17 virulence gene were detected in group B1.The results showed that the serotyping and phylogenetic clustering of pathogenic Escherichia coli in dairy cow with diarrhea in some areas of Shandong Province were diverse,carrying a variety of virulence gene,which should be paid attention to and strengthened monitoring and prevention and control.

[Objective] To develop a high calcium,low fat and nutrient-rich tremella yogurt,and analyze its flavor and quality. [Method] The preparation process of tremella yogurt was optimized by single-factor test and orthogonal test,and the texture characteristics,acidity,total sugar content,protein content,fat concentration,calcium ion concentration,number of lactic acid bacteria and Escherichia coli of tremella yogurt under the optimal conditions were analyzed. [Result] The optimal formula of tremella yogurt was 20% of tremella pulp,14% of skimmed milk powder,6% of sucrose and 0.4% of stabilizer. The sensory score of the finished product was the highest when fermented at 41 ℃ for 8 h with this formula. Its texture characteristics detection viscosity was 4 430 mPa•s,hardness was 108 g,acidity was 82.48 °T,total sugar content was 10.92%,fat concentration was 1.782 g/100 mL,calcium ion concentration was 7.84 mg/100 mL,protein content was 22 mg/mL,and the number of lactic acid bacteria was 1.6×10⁸ CFU/mL and the number of Escherichia coli was 0. [Conclusion] This product has reduced the fat content within a certain range while retaining the nutritional value of calcium and protein,etc. It also innovated the taste while preserving the special flavor of yogurt.

Against the backdrop of deepening global economic integration and the vigorous development of China's dairy industry,foreign capital mergers and acquisitions （M&As） in China have shown a sustained active trend. While foreign investment injects capital momentum into the dairy industry,the accompanying monopoly risks such as abuse of market dominance and distortion of competition order cannot be ignored. Taking China's dairy industry as the research field,this paper systematically analyzed the monopoly hazards in foreign capital M&As and the practical necessity of antitrust regulation. Combining the mature international experience of the EU,the United States and other countries,it put forward targeted suggestions from the dimensions of improving the legal system and optimizing the review mechanism,so as to provide theoretical support and practical reference for building an antitrust regulation system with both industry adaptability and national economic security protection function.

Cottonseed,as a high-quality protein source,has the advantages of wide availability,rich nutrition and low price,and its application in China's livestock and poultry production is becoming more and more widespread. However,if cottonseed （meal） is not used properly in the diet,it is easy to cause gossypol poisoning in animals.For dairy cows,the migration of gossypol into milk not only involves the metabolism of gossypol by ruminants but also the quality and safety of dairy products,thus it should be given due attention.Based on this,the paper conducted a safety assessment of gossypol residues in raw milk by adding cottonseed to the diet on raw milk. The amount of free gossypol ingested by the human body through drinking milk was 0.002 3 mg/kg·d,which is far below the limit value of 0.086 mg/kg·d for free gossypol intake through vegetable oil in the GB 2716-2018 National Food Safety Standard for Vegetable Oils.

Metabolic imbalance in early lactation dairy cows often leads to abnormal oestrus or lack of oestrus,which seriously affects reproductive efficiency. This study compared the metabolic and reproductive function differences between cows in estrus and anestrus through literature analysis. The results showed that cows in estrus had enhanced blood glucose（4.2~5.6 mmol/L）,lipid （triglyceride elevation of 12%~18%）and protein metabolism,and active ovarian activity（LH peak 15~20 IU/L）,and the conception rate reached 55%~60%,while cows in anestrus had a negative energy balance （glucose<3.8 mmol/L,NEFA>1.2 mmol/L） and mineral deficiency （blood calcium<1.2 mmol/L）,which resulted in abnormal estrus. Mineral deficiencies （blood calcium<2.2 mmol/L） resulted in ovarian quiescence （follicle diameter <10 mm） and reduced hormone levels （FSH<5 IU/L）. Reproductive performance was significantly improved by dietary addition of per rumen fat （7%~8%） and GnRH combined with PGF2α treatment. This study provides a theoretical basis for nutritional and reproductive management of early lactation cows.

The dairy industry is an indispensable part of building a healthy China and a stronger nation. National dairy core breeding farms serve as key entities in the dairy cattle breeding system,and their management standards directly influence the genetic progress of herds. This paper reviewed the selection criteria for national dairy core breeding farms and the current breeding status of the 26 designated farms. Additionally,specific measures are proposed to strengthen breed registration,performance testing,and genetic evaluation,aiming to provide references for dairy cattle breeding professionals.

Pseudomonas spp. is one of the most common genera of cryophilic bacteria in raw milk,and in order to explore the main factors affecting the kinetic parameters of Pseudomonas spp.,this study carried out a meta-analysis by quantitatively integrating the kinetic parameters of microorganisms and quantifying the variability of the strains.By statistically analyzing the growth parameters of more than 750 Pseudomonas spp. under different conditions and predicting their minimum growth temperatures（Tmin） based on the square root model,the results showed that the overall Tmin value of Pseudomonas spp. was -4.06 ℃,with the Tmin of strains 1248 and E52 in the culture medium being -5.38 ℃ and -6.36 ℃,respectively.In a low-temperature environment,the high initial inoculum size （Y₀,log CFU/mL） in UHT milk significantly shortened the growth retardation period,allowing the microorganisms to enter the logarithmic growth period（λ） more quickly even at lower temperatures.The distribution of maximum specific growth rate（μmax） under the combined effect of temperature,pH value, activity water（Aw） and NaCl concentration ranged from 0.04 h^-1 to 1.63 h^-1.In addition,NaCl concentration（1.0% to 7.5%） had a significant inhibitory effect on the growth of Pseudomonas spp..This study provided important reference basis for the safety,production optimisation and quality control during the production of milk and dairy products.