China Dairy

Effects of Heat Stress on Dairy Cow Reproductive Performance and Regulatory Strategies Involving Reproductive Hormones

China Dairy. 2025, (8): 15-20.

Heat stress is a critical environmental factor affecting the reproductive performance of dairy cows,leading to endocrine disorders,impaired ovarian and uterine functions,abnormal estrus behaviors,and significantly reduced conception rates and reproductive efficiency. This paper systematically elaborated on the physiological impacts of heat stress on the reproductive system of dairy cows,with a focus on regulatory strategies involving reproductive hormones（such as GnRH,progesterone,FSH/LH,and PGF2α）. These strategies include the optimization of hormone administration protocols,dosage adjustments,and their synergistic application with comprehensive management measures such as environmental control,nutritional support,and precision monitoring. Practical evidence demonstrates that scientifically applied hormonal interventions,combined with integrated management,can effectively enhance the reproductive performance of dairy cows under heat stress conditions.

The Antimicrobial Strategies against Staphylococcus aureus-induced Bovine Mastitis

China Dairy. 2025, (8): 67-74.

Mastitis is a common disease affecting dairy cows globally,primarily caused by Staphylococcus aureus,and is typically treated with antimicrobial drugs administered via intramammary and intramuscular injections.However,with the increasing rise of antimicrobial resistance,the treatment faces greater challenges and the available therapeutic options are gradually diminishing.The formation of biofilms formation and the adhesion of pathogens to mammary epithelial cells complicate treatment further.This paper discusseed factors such as the rise in antimicrobial resistance,biofilm formation,and intracellular bacterial survival,analyzing the challenges of conventional antibiotic treatment for mastitis.Additionally,it introduces alternative therapeutic approaches,including phytochemicals,antimicrobial peptides,bacteriophage therapy,and graphene-based nanomaterials,which may address the shortcomings of current antimicrobial treatments and mitigate the threat of antimicrobial resistance to mastitis treatment.This paper aimed to explore emerging alternative approaches in the treatment of mastitis,with the goal of providing robust support for future clinical therapies.

Practical Application and Key Management Strategies of Estrus Synchronization Technology in Dairy Cows

China Dairy. 2025, (8): 21-26.

Estrus synchronization technology in dairy cows is a core method for modern dairy farms to enhance reproductive efficiency and economic benefits. By employing hormonal regulation and precise management, this technology concentrates the estrous cycle of dairy cows within the "golden breeding period" of 50~80 days postpartum, effectively reducing days open, improving conception rates, and minimizing the risk of missed breeding. This paper systematically elaborated on the stratified implementation of estrus synchronization technology on dairy farms, including treatment strategies for different groups such as postpartum unbred cows, open cows, heifers, and adult cows. It also analyzed key influencing factors such as animal mixing, headlock utilization, effectiveness of drug administration, and estrus detection. Furthermore, a data supervision system centered on the "TAI proportion" is proposed to promote the transition from experience-based management to data-driven decision-making, providing practical guidance for improving reproductive management on dairy farms.

Bovine staphylococcal mastitis and its Defense Mechanisms

China Dairy. 2025, (8): 37-46.

Bovine staphylococcal mastitis is primarily caused by Staphylococcus aureus and non-aureus staphylococci.S. aureus is the most common pathogenic bacterium responsible for mastitis,capable of inducing acute or chronic infections in the mammary gland through its virulence factors,leading to reduced milk production and elevated somatic cell counts in milk. Although non-aureus staphylococcal strains are generally considered minor pathogens,they can also cause subclinical mastitis in dairy cows and impair milk quality.Staphylococci evade the host's immune defenses through various mechanisms,including biofilm formation,intracellular survival,and the production of immune evasion factors. Additionally,by inducing autophagy and altering cell wall structures,staphylococci enhance their persistence and pathogenicity within the host.The host immune response involves the coordinated action of innate and adaptive immunity, with neutrophils and macrophages playing a critical role in early immune defense,while antibodies and cell-mediated immune responses contribute to infection clearance. This review aimed to analyze the pathogenic and defensive mechanisms of bovine staphylococcal mastitis,providing new insights for disease prevention and treatment.

Analysis of Working Capital Management in Manor Ranch Based on Channel Theory

FANG Ruixin

China Dairy. 2025, (8): 30-36.

With socio-economic development, working capital management has become an increasingly important component of financial management theory. In the face of ongoing market changes and intense competition, sound working capital management is essential for the stable operation and long-term development of enterprises.Therefore,companies need to strengthen their working capital management. Due to their specific characteristics,dairy enterprises often require large-scale working capital to support production,making it even more critical for them to enhance their working capital management capabilities.This paper took Manor Ranch as the research object and analyzed the effectiveness of its working capital management based on channel theory,aiming to propose suitable improvement strategies for corporate working capital management.

Genotyping and Drug Resistance Analysis of Toxin Genes in Clostridium perfringens from Calf Diarrhea--A Case Study of a Large-scale Dairy Farm in Shandong Province

China Dairy. 2025, (8): 54-60.

[Objective] In order to find out the etiology and pathogen resistance of diarrhea calves in a large-scale dairy farm in Shandong Province,the pathogenic identification and drug resistance analysis were carried out. [Method] A total of 18 samples of mesenteric,lung,spleen and other tissues of dead calves were collected aseptically and put into sampling bags. Through bacterial isolation and culture and biochemical test,bacterial 16 S rRNA was amplified by PCR and toxin typing was identified. The K-B agar diffusion paper method was used to test the drug resistance of the isolated strains,and 14 drug resistance genes were detected by PCR electrophoresis. [Result] The results showed that 5 strains of C.perfringens type C were detected,and the detection rate was 27.8%. The isolated bacteria showed resistance to a variety of antibiotics,and β-lactams,aminoglycosides,sulfonamides and chloramphenicol resistance genes were detected. [Conclusion] The results showed that C.perfringens type C was the pathogenic bacteria causing diarrhea in calves on dairy farms,and it was resistant to some antibiotics. The results of this study provide a reference for the prevention and control of Clostridium perfringens in dairy farms.

In-depth Analysis of Reproductive Data and Efficiency Optimization Strategies in Modern Dairy Farms

China Dairy. 2025, (8): 2-7.

A large-scale dairy farm in China suffered an annual profit loss of up to 8 million RMB due to neglect of key reproductive indicators.This case highlights that reproductive efficiency has become a decisive factor affecting the economic benefits and sustainable development of dairy farms under intensive farming systems.This study focused on reproductive data from large-scale farms,systematically analyzing the calculation methods,influencing factors,and improvement strategies for key indicators such as 21-day pregnancy rate,breeding rate,conception rate,and 150-day non-pregnancy rate.Using real production data, practical application approaches are illustrated,and comprehensive improvement plans are proposed,including calibration of management software parameters,enhancing timeliness of estrus detection and pregnancy diagnosis,and optimizing synchronization protocols.The results showed that through in-depth interpretation and precise application of reproductive data,farms can fully grasp the reproductive status of the herd,significantly improve expansion efficiency,accelerate genetic progress,and optimize production benefits.Efficient management of reproductive data serves as a critical foundation for achieving refined operations and maximizing economic benefits in large-scale dairy farms.

Regulation Strategies and Application Effects of Hormones in Dairy Cows under Heat Stress

China Dairy. 2025, (8): 8-14.

Heat stress exerts significant negative impacts on the production performance, reproductive function, and immune system of dairy cows, leading to a 15%~20% decrease in milk yield, a 25%~35% reduction in conception rate, and various health disorders. This paper systematically elaborated the mechanisms through which heat stress affects dairy cows, with a focus on the scientific application strategies of reproductive hormones （such as GnRH and progesterone）, glucocorticoids （such as dexamethasone）, and melatonin in alleviating heat stress. Practical cases from dairy farms in both northern and southern regions demonstrate the effectiveness of hormonal regulation in enhancing stress resistance,improving reproductive efficiency, and restoring production performance. The study emphasized that hormone use should adhere to the principles of short-term and low-dose application, combined with comprehensive measures such as physical cooling and nutritional adjustments, to ensure dairy product safety and farming profitability. This paper provides a theoretical basis and practical guidance for dairy farms to mitigate heat stress.

A Rapid Detection Method for Determination of Protease Activity in Dairy Products

China Dairy. 2025, (1): 46-49.

[Objective] The bitterness of high calcium milk is mainly caused by the hydrolysis of casein by endogenous or exogenous proteases in milk and the formation of bitter free amino acids and oligopeptides. In order to control quality problems caused by proteases,it is necessary to measure the protease activity in milk.[Method] At present,there is no national standard method for detecting protease activity in milk and dairy products. This study introduced a rapid detection method for determination of protease activity in milk and dairy products by UV spectrophotometer-Folin method.[Result] The standard curve range used in this research was linear and meets the test requirements. The results of precision and spiked recovery experiments indicated that the spiked recovery rate was within the normal range.[Conclusion] The UV spectrophotometer-Folin method can be applied to the determination of protease activity in milk and dairy products.

Determination of 83 Pesticide Residues in Raw Milk by High Performance Liquid Chromatography Tandem Mass Spectrometry

China Dairy. 2025, (1): 71-79.

[Objective] To establish a high-performance liquid chromatography tandem mass spectrometry analysis method for multiple pesticide residues in raw milk.[Method] Raw milk samples were extracted with acetonitrile,purified with 150 mg of N-propylethylenediamine（PSA）,900 mg of magnesium sulfate and 15 mg of C18,and then eluted with liquid phase gradient.The samples were detected by electric spray（ESI+/ESI-）,and quantified by matrix matching external standard method.A rapid qualitative and quantitative analysis method for 83 pesticide residues in raw milk was established.[Result] The results of method validation showed that 83 pesticide residues exhibited good linearity within the range of 0.5 μg/L to 100 μg/L,with a correlation coefficient R²>0.99.The recovery rate of adding at three levels（0.010 mg/L,0.020 mg/L,0.100 mg/L） is 32%~134%,with a relative standard deviation of 0.3%~8.5%.[Conclusion] This experimental method is simple to operate,time-consuming,and suitable for rapid screening and quantitative analysis of pesticide residues in raw milk.It has practical application value. Using this method,83 pesticide residues were detected in 50 batches of raw milk,all of which meet the requirements of the GB 2763—2021 National Food Safety Standard Maximum Residue Limits for Pesticides in Food for raw milk.