Heat stress poses a significant challenge to the ruminant livestock industry under the context of global warming, severely impacting animal production performance, immune function, and reproductive efficiency. Chromium, as an essential trace element for animals, plays a key role in regulating glucose and lipid metabolism, enhancing antioxidant capacity, and maintaining immune function. This review summarized the detrimental effects of heat stress on ruminants and its underlying mechanisms, and introduced the sources, types, and application effects of chromium under heat stress conditions. It focused on the ameliorative effects of chromium supplementation on the lactation performance, growth performance, and reproductive performance of ruminants. Furthermore, the review explored the mechanisms of action, including enhancing insulin sensitivity, regulating glucose metabolism, improving antioxidant capacity, boosting immune function, and modulating the rumen microbiota. This review also analyzed existing research limitations, such as insufficient comparability among different chromium sources and the lack of standardized dosage, and proposed future research directions, aiming to provide a theoretical basis and practical reference for alleviating heat stress in ruminants.

The immune function of dairy ruminants is a core factor in safeguarding their health status, production performance, and product quality. Nutrients, as the material basis for life activities, also serve as key signaling molecules regulating immune function. Through multiple pathways, such as directly acting on immune cells or indirectly modulating the gastrointestinal microbiota, nutrients profoundly influence the immune function of dairy ruminants. This paper systematically reviewed the direct regulatory mechanisms of key nutrients, such as amino acids and fatty acids, on immune cells, the indirect immune regulatory pathways of nutrients via the gastrointestinal microbiota and their metabolites, the role of nutrients in maintaining the intestinal physical and immune barrier, and the functions of nutrients in alleviating oxidative stress and regulating the balance of inflammatory cytokines. Furthermore, it summarized application strategies for immune enhancement, including the use of functional feed additives, precision nutrition, and phase-feeding. The aim is to provide a theoretical reference for formulating precision nutrition plans, enhancing immunity, and promoting healthy farming practices for dairy ruminants.

Driven by the dual strategies of the comprehensive "antibiotic ban" in feed and the "low-carbon" transformation of animal husbandry developing natural, green and efficient antibiotic-substitute feed additives has become an urgent demand for the sustainable development of the breeding industry. As natural active macromolecules derived from marine algae, algal polysaccharides have become one of the research hotspots in the field of feed additives due to their unique structural characteristics and multi-dimensional biological functions. This paper systematically reviewed the classification, structural characteristics and core biological functions of brown algae, red algae, green algae and microalgae polysaccharides. This paper reviewed the research progress of their application in monogastric animal and ruminant production, focusing on their application potential and mechanisms in regulating rumen fermentation, enhancing immune function, improving lactation performance and maintaining intestinal health in dairy goats. This paper identified the key problems existing in current research and industrial application, and proposed targeted future research directions and industrial application suggestions, aiming to provide a systematic theoretical reference for the scientific application of algal polysaccharides in the green and healthy breeding of dairy goats.

Against the dual backdrop of global warming and China's strategy for revitalizing the dairy industry, ruminant production systems that balance high productivity, high efficiency and low carbon footprint have emerged as a core research topic for the sustainable development of the sector. Centered on the synergistic advancement of intelligent nutritional regulation and green emission reduction, this paper elaborates on the synergistic mechanisms linking ruminant nutrition, animal health and pollutant mitigation from three dimensions: nutritional metabolism, microecological interaction and stress regulation. It systematically reviews the current applications of smart technologies—including Internet of Things (IoT) sensors, big data and machine learning, and intelligent feeding equipment—in precision nutritional management, and analyzes the merits and inherent limitations of closed-loop management enabled by these technologies. This work further highlights technological innovations under the low-carbon breeding framework, such as the exploitation of novel feed resources, application of eco-friendly additives and formulation of low-emission diets, alongside their practical industrial performance. Four pivotal challenges prevailing in this field are identified: fragmented research on the synergistic nutrition-health-emission reduction mechanisms; poor scalability of smart breeding technologies; unsatisfactory economic viability and long-term stability of emission abatement techniques; and the absence of unified integrated evaluation criteria for the industry. To address the above bottlenecks, future research priorities and industrialization pathways are prospected, covering in-depth deployment of multi-omics technologies, development of low-cost intelligent facilities, establishment of differentiated technical frameworks for farms of varying scales, and construction of comprehensive emission assessment systems. This study intends to provide scientific evidence and theoretical support for the intelligent, healthy and green transformation of China's ruminant livestock industry.

The regulation of nutritional immunity in dairy cows is a core aspect of ensuring herd health and enhancing production performance, and precision nutritional intervention has become an important direction in modern dairy farming. The rapid development of multi-omics technologies has provided effective tools for deciphering the complex regulatory mechanisms between nutrition and immunity in dairy cows. This paper systematically reviewed the application progress of multi-omics technologies in areas such as intestinal microecology-immune interactions, immunoregulatory mechanisms of key nutrients, nutritional stress responses, and the formulation of precision nutritional strategies. It further explored the central role of multi-omics technologies in advancing precision regulation of nutritional immunity in dairy cows, offering a reference for healthy dairy farming and high-quality industry development.

This paper reviewed the intrinsic mechanisms through which heat stress affected reproductive performance in dairy cows, scientific assessment methods, and integrated mitigation strategies.It provided an in-depth analysis of the physiological and molecular mechanisms by which heat stress impairs fertility through multiple pathways, including inducing oxidative stress, disrupting endocrine homeostasis, impairing oocyte quality and embryonic development, and interfering with epigenetic programning.The paper explored heat stress assessment systems based on the temperature-humidity index, physiological indicators (such as rectal temperature and respiratory rate) , and behavioral changes, and analyzed their associations with key reproductive traits such as conception rate and the interval to first postpartum ovulation.It comprehensively reviewed current research progress and the potential of strategies to mitigate the negative effects of heat stress, including genetic selection, precise nutritional regulation, environmental improvements, and emerging biotechnologies, offering theoretical foundations and practical guidance for dairy farms to establish efficient heat stress response systems and enhance reproductive efficiency.

Heat stress caused by high temperatures in summer is a key challenge restricting the profitability of dairy farming. It not only reduces milk yield but also significantly impairs the reproductive performance of dairy cows. This paper systematically reviewed the mechanisms by which heat stress damages the physiological functions, endocrine homeostasis, and reproductive performance of dairy cows, with a focus on analyzing the negative effects of high-temperature enviromments on estrus expression, follicular development, early embryonic survival, and pregnancy success rates. Combined with field trial data, this paper elaborates on the application effects of the novel gonadotropin-releasing hormone (GnRH) analogue buserelin in scenarios such as fixed-time artificial insemination synchronization, reducing early embryonic mortality, and treating ovarian cysts. The study confirmed that buserelin can significantly alleviate heat stress-induced reproductive damage, improve summer conception rates, and enhance overall reproductive efficiency in dairy cows by regulating the endocrine status, increasing progesterone concentrations, and improving oocyte quality and the uterine environment. This provided a scientifically based practical solution for reproductive management in large-scale farms during summer.

Heat stress is a critical environmental factor impairing reproductive performance in dairy cows during summer, with particularly detrimental effects on early embryonic survival. This review systematically summarized the impacts and underlying mechanisms of heat stress on early embryo survival in dairy cows. It begins by outlining the assessment indicators of heat stress and its multifaceted reproductive consequences, including abnormal estrus, reduced fertilization rates, and increased embryonic mortality. The mechanisms are then analyzed from both maternal and embryonic perspectives. On the maternal side, heat stress disrupts the hypothalamic-pituitary-ovarian axis, elevates reproductive tract temperature, and alters uterine blood flow and endometrial secretory functions, thereby compromising the embryonic microenvironment. On the embryonic side, heat stress induces oocyte aging, interferes with embryonic genome activation, triggers apoptosis, and disturbs redox homeostasis, with embryonic stage and genotype playing key roles in differential thermotolerance. Furthermore, this review summarized commonly applied interventions in dairy production, such as timed ovulation-fixed-time insemination, GnRH/hCG administration, and progesterone supplementation, aimed at mitigating the negative effects of heat stress on embryo survival. This review aimed to provide both theoretical foundations and practical strategies for improving dairy cow reproductive performance during hot seasons.

Dairy farming is one of the rural industries that contribute to farmers' prosperity.Smallholder farmers constitute an integral component of the dairy farming sector and play an indispensable role in industrial development. Mostly located in rural areas, they contribute to ensure supply, employment absorption, and the enhancement of farmers'income and welfare.This paper targeted dairy farmers in Liaocheng City with a herd size of fewer than 100 dairy cattle, through questionnaire surveys and field visits, the study investigated the current production and management status of these farmers.The SWOT analysis method is applied to study the development environment of smallholder dairy farmers, synthesize their internal strengths and weaknesses, and analyze external opportunities and threats, thereby construct four strategic combinations: SO, WO, ST, and WT.In light of the overall development trends in China's dairy industry, the SO strategy is prioritized. Accordingly, this paper proposed a series of countermeasures and recommendations to promote the high-quality development ofsmallholder dairy farmers in Liaocheng City, including enhancing consumer demand, advancing standardized production, strengthening the supporting role of science and technology as well as talent development, improving organizational forms, increasing forage supply and breed improvement efforts, establishing a sound market system, and promoting the integrated development of agriculture, culture, and tourism.