Mapping the Intellectual Structure and Thematic Evolution of Dietary Fat Research in Ruminants: A Comprehensive Bibliometric Analysis

The bibliometric analysis of literature related to dietary fat supplementation in ruminant nutrition, based on data from the Scopus database, provides several insights into the research landscape on this topic (Table 1). The analysis covers a timespan from 1964 to 2024, and a total of 450 documents have been published across 104 different sources, including articles, books, and other scholarly outlets. This reflects a broad range of platforms that contribute to the dissemination of research on this subject. The dominant type of document is journal articles, with 413 entries, followed by 24 reviews, 12 conference papers, and one book chapter.

Table 1. Summary statistics of the articles collected (Source: Biblioshiny)

The annual growth rate of publications is 2.72%, indicating steady interest and expansion of the field over time. The mean age of articles is 22.8 years, suggesting that much of the foundational work in this area is relatively old but remains relevant. Each article, on average, has been cited 48.09 times, which indicates a significant academic impact and relevance within the broader field of animal nutrition and livestock science. The analysis identifies 1,352 authors who have contributed to the literature. Of these, only 15 have produced single-authored works, contributing to 21 such articles. This highlights that research in this area is largely collaborative, as evidenced by an average of 4.35 co-authors per article. Furthermore, 20.44% of the publications involve international co-authorship, signifying a moderate level of global collaboration, which is important in addressing universal challenges in livestock nutrition.

3.1 Annual growth publication

Figure 1 presents a detailed view of the annual scientific publications related to dietary fat supplementation in ruminant nutrition from 1964 to 2024, revealing several significant trends and phases in research activity. In the initial years (1964-1970s), the research output was minimal, averaging fewer than 2 articles per year. This is indicative of a nascent phase in the scientific exploration of dietary fat in ruminant nutrition. By the early 1980s, there was a noticeable rise, with some years producing 4 to 6 articles. During this 25-year period, publication rates increased by around 200% compared to the starting decade (1960s), but still remained relatively low in comparison to later years. The period from 1990 to 2000 marks a turning point, with a sharp increase in research output. This decade saw consistent publication rates, peaking at 16 articles in certain years, such as 1997 and 1999. Compared to the previous decade (1980s), there was an increase of over 300% in the number of annual publications. This rapid expansion can be attributed to several factors, such as growing awareness of the role of dietary fats in enhancing livestock productivity, advances in animal nutrition science and methodologies, and a global surge in the demand for efficient livestock production systems.

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Figure 1. Trends in the annual number of publications on dietary fat supplementation in ruminant nutrition, retrieved from the Scopus database (1964-2024)

From 2000 onward, the trend became more complex. While the general trajectory still shows growth, the number of publications fluctuates more significantly. For instance, while there are consistent peaks of 16 articles per year in 2010, 2014, 2016, and 2019, some years like 2001 and 2021 witness a drop to 5 articles or fewer. This fluctuation could be tied to multiple factors: shifts in research funding and priorities, technological advancements in alternative areas of ruminant nutrition, and saturation of certain subtopics within the research field. However, despite these fluctuations, the overall trendline shows a positive slope, indicating that research in this area continues to grow, albeit at a more moderate rate than the sharp rise seen in the 1990s. For example, by the early 2020s, the number of publications still averaged 10–12 articles per year, representing a 100% increase compared to the 1980s average.

The trendline with an R² value of 0.3905 indicates that about 39% of the variance in annual publication output can be explained by the passage of time. This reflects a long-term commitment to the topic, with overall growth in scientific interest despite short-term fluctuations. The cumulative increase in publications over 60 years was dramatic, from just a handful of articles in the early years to consistent double-digit annual outputs in more recent decades, representing an approximate 800% increase since the 1960s. The years 1997, 2010, 2014, 2016, and 2019 each produced 16 articles, the highest observed in any single year. These peaks likely correspond to either important breakthroughs or increased global focus on food production due to demographic and economic shifts. For example, the peak in 2010 might be tied to global concerns about food security and the increasing demand for meat, driving research into optimizing ruminant nutrition through dietary fat supplementation.

3.2 The most influential contributors

3.2.1 Authors

The data on the most prolific authors in the field of dietary fat supplementation in ruminant nutrition, presented through both Table 2 and the graphical timeline (Figure 2), displays a detailed overview of key contributors and their influence in this research area. Drackley JK and Palmquist DL emerge as the most impactful authors, each with an h-index of 18 and a g-index of 19, indicating their significant contribution to the field. Palmquist DL has the highest total citation count at 2,969, reflecting the foundational impact of his research since 1971 and continuing steadily over the decades. His larger dots in the 1990s and 2000s indicate periods of high productivity and impact. His work has been pivotal in understanding how different types of fats influence lactation and overall animal health, shaping both academic research and practical applications in the dairy industry. Drackley JK, starting in 1992, especially from the late 1990s to the 2010s, has also made substantial contributions, particularly in understanding the metabolism of fatty acids in dairy cattle and the nutritional requirements during various stages of lactation. His relatively high m-index of 0.545 signifies a consistent impact over time.

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Figure 2. Timeline of key authors' publication activity and impact in dietary fat supplementation research, with dot size representing citations per year

Table 2. Authors' local impact

Chilliard Y ranks third, with an h-index and g-index of 14 and 14, respectively, and a total citation count of 2,354. His research, starting in 1993, with a visible peak in research activity during the early 2000s, is evidenced by larger dots. His work focused on lipid metabolism in ruminants and how dietary supplementation affects milk quality and animal physiology. His work has been instrumental in advancing the understanding of the nutritional manipulation of milk fatty acid profiles, which is vital for both animal productivity and human health.

Firkins JL, with an h-index of 13 and a g-index of 13, has contributed significantly with 679 citations and 13 publications since 1990. Firkins' peaks around the late 1990s and early 2000s. His research revolves around microbial fermentation in the rumen and the role of dietary fats in modulating rumen microbial ecology and nutrient utilization. This work is crucial for optimizing feed efficiency and reducing methane emissions, which are critical for sustainable livestock management.

Eastridge ML, Jenkins TC, and Clark JH also play vital roles. Eastridge ML and Jenkins TC each have an h-index of 12, indicating their valuable contributions to understanding fat metabolism and its implications for dairy cow health and productivity. Jenkins TC, starting his research in 1980, has focused extensively on the chemical and metabolic processes involving fats and oils in dairy cow diets. Clark JH has contributed significantly to understanding dietary influences on lactation performance, starting his work in 1989, with his research being widely cited and highly regarded in the field.

Table 3. Lotka's law distribution

Table 3 provides an application of Lotka's law in the context of authorship productivity in the field of dietary fat supplementation research. Lotka's law states that the number of authors who produce n papers is inversely proportional to n². This trend is clearly illustrated in the table, where the number of authors significantly decreases as the number of documents written increases.

For authors who have written only one document, there are 1,089 contributors, which constitutes 80.5% of the total authors. As the number of documents written increases to two, the number of contributing authors drops sharply to 149, representing only 11% of the total. This declining trend continues with three documents written by 49 authors (3.6%), four documents by 19 authors (1.4%), and five documents by only 15 authors (1.1%).

This distribution confirms Lotka's law by demonstrating that the majority of authors contribute only a single paper to the field, while a smaller number of highly prolific authors contribute multiple documents. This pattern is common in academic research and reflects how knowledge production is concentrated among a few highly active researchers, while many others contribute sporadically. Understanding this distribution is essential for identifying key contributors and understanding the dynamics of research productivity in the field.

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Figure 3. Worldwide scientific production of dietary fat supplementation in ruminant nutrition-related publications by country affiliations, measured by the number of author appearances

3.2.2 Countries

The analysis of countries' scientific production regarding dietary fat supplementation in ruminant nutrition shows a diverse geographical distribution of research contributions (Figure 3). Researchers from 58 different countries participated in producing the collected documents, indicating a broad international interest in this topic. The world map visualization highlights that countries with higher research output are shaded in darker colors, while those with lower output are represented in lighter shades. The bar chart provides a clearer quantitative depiction of each country's contribution (Figure 4).

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Figure 4. Number of documents published by country

The United States stands out as the most prolific contributor, with 592 documents, accounting for approximately 41.8% of the total publications (Figure 4). This is a significant proportion, indicating the country's leading role in research on dietary fat supplementation in ruminant nutrition. France follows with 154 documents, making up about 10.9% of the total, while Brazil contributes 133 documents, representing around 9.4%. The United Kingdom and Spain each contribute 111 and 95 documents, respectively, equating to 7.8% and 6.7%. Other notable contributors include Australia (91 documents, 6.4%), Canada (84 documents, 5.9%), and Germany (48 documents, 3.4%). Indonesia and Switzerland have also made substantial contributions, with 43 (3.0%) and 36 (2.5%) documents, respectively.

The clustering of countries based on their research collaboration patterns reveals six distinct groups (Figure 5). Cluster 1 (red nodes) includes six countries: Belgium, India, Iran, the Netherlands, Switzerland, and Thailand. This cluster represents about 11.8% of the total countries involved in the research, indicating a moderate level of collaboration. Cluster 2 (green nodes), also consisting of six countries—Colombia, Finland, Italy, Spain, Sweden, and the United Kingdom—similarly accounts for around 11.8% of the countries. These clusters indicate potential research networks or regional collaborations that could influence research output and focus.

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Figure 5. Visualization of the international research collaboration network

Cluster 3 (blue nodes), which contains five countries—Australia, Brazil, Israel, Mexico, and the United States—accounts for 9.8% of the total countries. This cluster includes the leading contributor, the United States, suggesting strong collaborative links between these countries. Cluster 4 (yellow nodes) comprises four countries: Denmark, Egypt, France, and Japan, representing 7.8% of the countries. This cluster includes France, the second most prolific country, indicating substantial collaboration within this group.

Cluster 5 (purple nodes), containing three countries—Canada, China, and South Korea—represents 5.9% of the total countries. Cluster 6 (pink nodes), contains only two countries-Germany and Turkey. These countries have shown considerable research output, contributing collectively to the global body of knowledge on dietary fat supplementation. The clustering patterns suggest that research collaborations are often regionally focused, with significant partnerships observed between neighboring countries or those within the same economic or academic alliances.

The analysis reveals that while a few countries dominate the research output on dietary fat supplementation in ruminant nutrition, there is a significant level of international collaboration. This global scientific engagement is crucial for advancing the field, sharing diverse perspectives, and promoting the development of comprehensive and universally applicable findings. Understanding these geographical and collaborative dynamics can help researchers and policymakers identify key players, foster international partnerships, and guide future research directions in this critical area of animal nutrition.

3.2.3 Affiliations

Figure 6 shows the cumulative number of articles produced by different institutions over a period extending from 1964 to 2024. Each line represents a different institution, and the growth in the number of articles over time highlights the research productivity of each affiliation. The graph reveals that the University of Illinois is the most prolific institution, showing a steep rise in publication numbers starting from the late 1980s and maintaining consistent output, reaching over 70 articles by the present day. The Ohio State University and the University of Wisconsin follow closely with 43 and 32 articles, respectively. The presence of a large "Not Reported" category, with 49 articles, suggests that a significant portion of research comes from unreported or possibly diverse global affiliations, highlighting the widespread interest and collaborative nature of this field. Other affiliations like Ghent University, Clemson University, and South Dakota State University are notable for their contributions but have fewer articles, ranging from 24 to 28.

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Figure 6. Most relevant affiliations in dietary fat supplementation research

By integrating insights from both graphs, it is evident that a small number of institutions dominate research in dietary fat supplementation for ruminant nutrition. The steady rise in articles from top universities like the University of Illinois, Ohio State University, and the University of Wisconsin indicates sustained research interest and investment in this field. These institutions likely have specialized research programs, facilities, and funding that enable them to maintain high levels of productivity over decades. The visualization also suggests a strong presence of North American universities in leading research on this topic, with notable contributions from European institutions like Ghent University.

The graphs highlight not only the leading institutions but also the potential for collaborations and network-building among universities with aligned research interests. Researchers and stakeholders can use these insights to identify key academic hubs for collaboration, funding opportunities, and strategic partnerships to advance research on dietary fat supplementation in ruminant nutrition.

3.2.4 Interconnection between authors, countries, and affiliations

The three-field plot illustrates the interconnected relationships between affiliations, countries, and authors in dietary fat supplementation research (Figure 7). Leading universities like the University of Illinois and the Ohio State University are closely linked to key authors such as Drackley JK and Clark JH, indicating these institutions as major research hubs. These authors, in turn, connect multiple institutions and countries, showcasing their central roles in collaborative research efforts. Countries like the USA, Spain anf France are heavily involved. The USA is showing the most connections, highlighting its global leadership in this field. This is evident from authors like Palmquist DL and Firkins JL, whose work is associated with American universities and extends globally. Similarly, France and Spain have strong ties to authors like Chilliard Y and Toral PG, reflecting their contributions through national institutions such as INRAE (Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement) and CSIC (Consejo Superior de Investigaciones Científicas), which are central to their research communities. The connecting lines reveal how influential authors bridge institutions and countries, forming a network where strong academic centers and cross-border collaborations drive impactful research in dietary fat supplementation.

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Figure 7. Tree-field plot visualizing the relationship between authors, affiliations, and countries in producing papers on dietary fat supplementation in ruminant nutrition research

3.3 Journal and citation

3.3.1 The most relevant journal

The data on the most relevant sources in dietary fat supplementation research highlights the pivotal roles of key journals (Table 4). The Journal of Dairy Science leads with the highest impact, evidenced by an h-index of 59, g-index of 94, and over 10,305 citations from 164 publications since 1967. The Journal of Animal Science follows with significant contributions across various livestock species, showing an h-index of 31 and 2,749 citations from 64 publications since 1966. The British Journal of Nutrition and Animal Feed Science and Technology also play crucial roles, focusing on the nutritional and feed technology aspects. Other journals like Animal, Meat Science, and Small Ruminant Research provide niche insights into lipid metabolism, meat quality, and specific animal management strategies. Together, these journals provide comprehensive coverage of the biochemical, physiological, and practical impacts of dietary fat supplementation in ruminant nutrition, guiding both scientific inquiry and practical applications.

Table 4. The most relevant journal

The brown cluster, centered around the Journal of Dairy Science (J. Dairy Sci.), is the most prominent and includes journals like the Journal of Agricultural and Food Chemistry and the Journal of Lipid Research, emphasizing research focused on dairy science, lipid chemistry, and ruminant nutrition (Figure 8). The red cluster, featuring journals like the Journal of Animal Science (J. Anim Sci.) and the Journal of Nutrition (J. Nutr.), covers broader aspects of animal nutrition, general nutrition science, and meat production, indicating strong thematic connections in studies examining the impact of dietary fat on animal health and production. The purple cluster, including the British Journal of Nutrition (Br. J. Nutr.) and Animal Feed Science and Technology (Anim. Feed Sci. Technol.), focuses on nutritional biochemistry and feed formulations, highlighting research on dietary interventions across various animal species.

The blue cluster serves as a bridge between dairy-focused and general animal science research, integrating journals like the Journal of the Science of Food and Agriculture to reflect an interdisciplinary approach combining food science, agriculture, and animal nutrition. The green cluster, represented by PLOS One, captures a broader, multidisciplinary perspective that spans veterinary science, animal nutrition, and biological sciences. Finally, the orange cluster further emphasizes specialized topics in animal nutrition and feed science, indicating frequent co-citation among studies discussing specific nutritional strategies for milk and meat production. This visualization offers a comprehensive understanding of the interconnectedness of journals in the field, highlighting core research areas and potential opportunities for researchers to identify foundational sources, conduct literature reviews, and establish collaborative efforts across thematic boundaries.

Table 5. The top 20 globally most-cited papers in the field of Dietary Fat, based on data retrieved from the Scopus database

3.3.2 The most cited papers and its caracteristics

The top 20 most cited papers on dietary fat supplementation in ruminant nutrition collectively provide a comprehensive understanding of the advancements in this field, ranging from foundational biochemical studies to innovative strategies that address both animal health and environmental sustainability (Table 5). The pioneering work by Palmquist and Jenkins [20] laid the groundwork for understanding the effects of dietary fat supplementation on milk production and milk fat composition in dairy cows, focusing on how different fat sources can alter lipid metabolism. This foundational knowledge was further built upon by Chilliard et al. [21], who explored how dietary fats, particularly conjugated linoleic acid (CLA), can be leveraged to modify the fatty acid profile of milk, making it healthier for human consumption. Meanwhile, Dewhurst et al. [22] expanded on this by comparing various fat sources and their impacts on rumen function and animal performance, emphasizing the need for sustainable fat supplementation strategies that maintain rumen health while enhancing productivity.

Studies [25, 26] delved deeper into the mechanisms of milk fat depression and biohydrogenation of unsaturated fatty acids within the rumen, providing insights into the interactions between dietary fats and rumen microorganisms. Their findings are critical in understanding how to manage these interactions to avoid negative effects on milk production while maximizing the benefits of fat supplementation. The physiological basis of these effects was further examined by Hayirli et al. [29], who focused on the lipid metabolism pathways influenced by specific fatty acids like CLA, contributing to a deeper understanding of the health benefits of dairy products for humans.

Woods and Fearon [28] provided a comparative analysis of the effects of different fat sources on ruminant growth, milk production, and feed efficiency, offering a foundation for optimizing feeding strategies based on specific production goals. Sanz Sampelayo et al. [32] took a novel approach by examining the effects of fat supplementation on methane emissions, addressing the environmental sustainability dimension of ruminant nutrition. This study aligns with current research trends that integrate nutritional strategies with climate change mitigation efforts. Similarly, Chilliard and Ferlay [24] investigated the molecular mechanisms underlying lipid metabolism affected by dietary fats, providing a molecular-level understanding that supports both animal health and human nutrition. The classic study by Doreau and Chilliard [27] on the microbial processes of biohydrogenation in the rumen is pivotal for comprehending the microbiological dynamics that influence fat metabolism and the overall efficacy of dietary fat supplementation strategies. This research serves as a fundamental reference for subsequent studies exploring the microbial ecology of the rumen in response to dietary interventions.

The next ten most cited papers continue to build on the foundational work in dietary fat supplementation by offering a mix of theoretical insights and practical applications. Many of these studies address the complex interactions between dietary fats, rumen microbiota, and animal metabolism. There is a clear emphasis on the molecular, metabolic, and environmental impacts of fat supplementation. Papers such as those by researcher [31, 33] are particularly significant for their contributions to understanding how dietary fat can be used strategically to manage both animal health and environmental impact—critical areas of focus as the industry moves towards more sustainable practices.

Figure 9 reveals that foundational research began to take shape in the 1970s, with significant growth in citations through the 1980s and 1990s, suggesting the establishment of key theories and methodologies. Notable peaks around the mid-1990s, early 2000s, and 2005 indicate the publication of influential studies or reviews that significantly impacted the field, likely representing breakthroughs or critical summaries of knowledge. The red line spikes in these years underscore the presence of pivotal works that deviated markedly from the citation norms, marking shifts in understanding. The decline in citations after 2010 suggests a reliance on more recent studies, signaling either a maturation of certain areas or a shift in research focus. The RPYS graph helps researchers identify key periods and influential works that have shaped the field, offering a roadmap for navigating its evolution and understanding current trends.

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Figure 9. Reference Publication Year Spectroscopy (RPYS) shows the distribution of cited references over time in dietary fat supplementation research

3.4 Keywords analysis

3.4.1 The most frequent words

The analysis identifies the top five keywords with the highest frequencies and total link strengths: "fatty acids" appears 70 times with a total link strength of 98, making it the most frequently discussed topic in the literature (Figures 10 and 11). This is followed by "dairy cows," with 33 occurrences and a total strength of 42; and "dietary fat," which appears 28 times with a total strength of 33. The word "conjugated linoleic acids," appearing 27 times with a total strength of 43; "biohydrogenation," which occurs 24 times and has a total link strength of 43; These findings suggest that the research on dietary fat supplementation in ruminant nutrition is heavily focused on the biochemical processes of fatty acids, the role of biohydrogenation, and the impacts on dairy cows, particularly concerning milk production and composition. This clustering and frequency analysis provides a comprehensive understanding of the dominant themes and key areas of focus within the field, allowing researchers to identify significant trends, relationships, and potential gaps in the existing literature.

Figure 10. Word cloud representing the most frequently occurring keywords in research on dietary fat supplementation in ruminant nutrition

Figure 11. Tree map of the most frequent keywords in dietary fat supplementation research

Figure 12. Co-occurrence network visualization of keywords in dietary fat supplementation research

The visualization presented in Figure 12 was generated using VOSviewer software, utilizing a co-occurrence analysis to identify the most frequently occurring keywords in the literature on dietary fat supplementation in ruminant nutrition. The analysis was conducted by selecting "Co-occurrence" as the type of analysis and "Author Keywords" as the unit of analysis. The counting method used was "Full Counting," which considers the total frequency of each keyword across all documents. A threshold was set whereby only keywords with a minimum of five occurrences were included in the analysis. Out of the 968 keywords present in the dataset, 42 keywords met this threshold.

The keywords are divided into five distinct clusters, each represented by a different color: red, green, blue, yellow, and purple. The first cluster, represented by red nodes, consists of 11 items related to fat supplementation and ruminal processes: "calcium long-chain fatty acids," "ether extract," "fat," "fatty acid digestibility," "lactating cows," "long-chain fatty acids," "milk composition," "protein," "ruminal fermentation," "soybean meal," and "tallow." Within this cluster, the largest nodes are "fat" and "ruminal fermentation". This cluster shows strong linkages with both the blue and yellow clusters, suggesting that studies focusing on fat supplementation are closely connected to rumen-level mechanisms and dairy production outcomes. 

The second cluster, represented by green nodes, is primarily associated with animal performance and specific fatty acid compounds contains 10 keywords: "beef," "cattle," "conjugated linoleic acid," "fish oil," "linoleic acid," "milk," "nutrition," "performance," "trans fatty acids," and "vaccenic acid." highlighted by "conjugated linoleic acids,". This cluster is moderately interconnected with the blue cluster, reflecting the dependence of fatty acid profiles and production traits on ruminal biohydrogenation pathways, but shows weaker direct links with the dairy-focused yellow cluster.

The third cluster, represented by blue nodes, includes 9 items: "biohydrogenation," "digestion," "forage," "in vitro," "lipids," "methane," "oil supplementation," "rumen," and "ruminants." The largest nodes in this cluster are "ruminants," "rumen," and "biohydrogenation. Its keywords demonstrate extensive co-occurrence links with multiple clusters, particularly the red cluster (fat digestion and fermentation processes) and the green cluster (fatty acid profiles and animal performance). This indicates that rumen metabolism and lipid transformation processes serve as a conceptual core connecting mechanistic, nutritional, and applied research streams. The fourth cluster, marked by yellow nodes, comprises keywords such as "dairy cows," "lactation," "linseed oil," "milk fat," "milk fat depression," and "milk fatty acid," with "dairy cows" being the most prominent node in this group. This cluster shows strong linkages with both the blue and yellow clusters, suggesting that studies focusing on fat supplementation are closely connected to rumen-level mechanisms and dairy production outcomes.

The fifth cluster, represented by purple nodes, contains the keywords "dietary fat," "digestibility," "fatty acids," "milk yield," "sheep," and "goat." Its weaker links to other clusters suggest that research on small ruminants forms a more distinct subfield, with less integration into the broader literature dominated by cattle- and dairy-oriented studies. Nevertheless, the prominence of “fatty acids” as the largest node in this cluster and across the entire network underscores its unifying role across species and research themes.

3.5 Thematic evolution

The visualization below represents the thematic evolution (Figure 13) and trend topics (Figure 14) of research on dietary fat supplementation in ruminant nutrition from 1992 to 2024. It shows how key research themes have developed and transformed over different time periods, reflecting shifts in research focus and advancements in scientific understanding.

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Figure 13. Thematic evolution of research topics in dietary fat supplementation for ruminant nutrition from 1964 to 2024

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Figure 14. Trend analysis of key research topics

During the early period from 1964 to 1991, research on dietary fat supplementation in ruminants primarily focused on foundational topics such as "fatty acids," "biohydrogenation," "dietary fats," and "fiber." The prominence of "fatty acids" indicates an early interest in understanding the basic role of fats in ruminant diets and how they impact animal metabolism and health. "Biohydrogenation," a process specific to the ruminant digestive system where unsaturated fatty acids are hydrogenated by microorganisms in the rumen, also emerged as a crucial area of study, highlighting the unique aspects of ruminant nutrition compared to monogastric animals. The presence of "fiber" in the thematic network suggests that initial studies were also concerned with balancing fat and fiber intake, given the importance of fiber in ruminant diets for optimal rumen function.

Between 1992 and 1997, research began to diversify with the introduction of new themes such as "soybeans," "body condition score," "digestibility," "milk fat depression," and "rapeseed oil." This period saw an increased focus on specific feed ingredients like "soybeans" and "rapeseed oil," likely driven by interest in the potential benefits and challenges of incorporating various oilseeds in ruminant diets. "Body condition score" and "milk fat depression" as emerging themes indicate a shift towards understanding the physiological and production-related responses of ruminants to dietary fat supplementation. The exploration of "digestibility" reflects a growing awareness of the importance of not just the type of fat, but also its digestibility and the subsequent effects on nutrient absorption and animal performance.