Review Article

Mapping The Scientific Evolution of Phytogenic Feed Additives in Broiler Nutrition: A Bibliometric Analysis

Muhammad Ridla1,2, Rita Mutia1*, Arif Darmawan1

1Department of Animal Nutrition and Feed Technology, Faculty of Animal Science, IPB University, Bogor 16680, Indonesia; 2Center for Tropical Animal Studies (Centras), IPB University, Bogor 16153, Indonesia.

Received | May 04, 2026; Accepted | June 11, 2026; Published | August 05, 2026

*Correspondence | Rita Mutia, Department of Animal Nutrition and Feed Technology, Faculty of Animal Science, IPB University, Bogor 16680, Indonesia; Email: [email protected]

Citation | Ridla M, Mutia R, Darmawan A (2026). Mapping the scientific evolution of phytogenic feed additives in broiler nutrition: A bibliometric analysis. Adv. Anim. Vet. Sci., 14(8):1747-1762.

DOI | https://dx.doi.org/10.17582/journal.aavs/2026/14.8.1747.1762

ISSN (Online) | 2307-8316

Copyright: 2026 by the authors. Licensee ResearchersLinks Ltd, England, UK.

This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

INTRODUCTION

Broiler chicken production is one of the fastest-growing sectors of the livestock industry and plays an important role in supplying affordable, high-quality animal protein worldwide. The sustainability and profitability of this industry are commonly evaluated through growth performance indicators such as body weight, weight gain, feed intake, and feed conversion ratio (FCR). For decades, antibiotic growth promoters (AGPs) were widely used in poultry diets to improve performance, feed efficiency, and gut health (Dibner and Richards, 2005). However, concerns regarding antibiotic residues and antimicrobial resistance have led to increasing restrictions on AGP use and encouraged the search for safer alternatives (Castanon, 2007; Gadde et al., 2017).

Among the proposed alternatives, phytogenic feed additives have gained considerable attention in recent years (Windisch et al., 2008). Phytogenics include herbs, plant extracts, and essential oils containing bioactive compounds that can improve digestive function, nutrient digestibility, and gastrointestinal health (Darmawan et al., 2022; Brenes and Roura, 2010; Greathead, 2003). Previous studies reported that phytogenics stimulate digestive enzyme secretion, modulate intestinal microflora, strengthen intestinal barriers, and improve intestinal morphology by increasing villus height and optimizing crypt depth (Amad et al., 2011; Windisch et al., 2008). These effects may enhance nutrient absorption, feed efficiency, and body weight gain in broiler chickens.

Despite the growing number of studies, the reported effects of phytogenic additives remain inconsistent and sometimes contradictory. Variations in plant species, bioactive compounds, extraction methods, dietary composition, supplementation levels, and environmental conditions contribute to differences among studies (Greathead, 2003; Windisch et al., 2008). In addition, the interactions between phytogenics, nutrient digestibility, gut microbiota, and intestinal structure are still not fully understood, making it difficult to synthesise existing findings and identify clear research directions (Brenes and Roura, 2010).

Bibliometric analysis provides a systematic and quantitative approach to evaluating scientific development, including publication trends, collaboration networks, thematic evolution, and knowledge structures (Aria and Cuccurullo, 2017; Cobo et al., 2011). Compared with traditional narrative reviews, bibliometric methods offer more transparent and reproducible evidence synthesis (Donthu et al., 2021). Although previous studies have extensively examined the biological effects of phytogenic additives in broilers, no study has comprehensively mapped the scientific landscape, research collaboration, and thematic evolution in this field. Therefore, this study aims to conduct a bibliometric analysis of phytogenic feed additive research in broiler chickens, focusing on growth performance, nutrient digestibility, gut health, and intestinal physiological responses. The findings are expected to identify research trends, knowledge gaps, and future directions for evidence-based phytogenic development.

MATERIALS AND METHODS

Data source

The bibliometric dataset was obtained from the Scopus database because of its extensive journal coverage, standardized indexing system, and suitability for quantitative bibliometric analysis. In addition, journal selection criteria focused on strong representation of publications in animal science and nutrition, veterinary medicine, and agricultural science to ensure adequate coverage of research on phytogenic feed additives in broiler chickens.

Search strategy

Searches were performed using the TITLE-ABS-KEY fields, which identify documents by title, abstract, or keywords. The search queries used in the database are presented in Table 1.

 

Table 1: Boolean search query on the application of phytogenic feed additives in broiler chickens.

Boolean search query

Title-ABS-Key (phytogenic* OR phytobiotic* OR "plant extract*" OR "herbal extract*" OR "essential oil*" OR botanical*) AND (broiler* OR "broiler chicken*" OR "meat-type chicken*") AND ("body weight gain" OR "growth performance" OR "feed intake" OR "feed conversion ratio" OR FCR OR digestibility OR "nutrient digestibility" OR "gut health" OR microbiota OR "gut microbiota" OR "intestinal morphology" OR "villus height" OR immunity OR "cecal microbiota")) AND PUBYEAR < 2026 AND (LIMIT-TO (LANGUAGE, "English")) AND (LIMIT-TO (DOCTYPE, "ar"))

 

The publication year of the articles was not restricted, enabling comprehensive coverage of research on phytogenic feed additives in broiler chickens. However, only English-language articles were included to ensure consistency in bibliometric analysis, keyword harmonization, and text interpretation. This approach minimized potential discrepancies arising from language-specific terminology, translation issues, and differences in indexing practices across databases.

Data collection and screening

The retrieved bibliographic records were exported in CSV format. Before analysis, the dataset was screened to improve data accuracy. Duplicate records and data that did not meet the predefined eligibility criteria were removed. Articles were considered eligible if they explicitly investigated plant-derived phytogenic application in broiler chickens and reported growth performance, digestibility of nutrients, intestinal health, microflora composition, or intestinal physiological responses. Studies involving non-broiler, or those not related to the application of phytogenic, were excluded. The screening process followed PRISMA 2020 guidelines to ensure transparency, consistency, and reproducibility (Page et al., 2021). Two independent reviewers screened the titles, abstracts, and full-text articles based on predefined eligibility criteria. Disagreements were resolved through discussion or adjudicated by a third reviewer when necessary.

Bibliometric analysis

Bibliometric analysis was conducted using Bibliometrix (R package, version 4.3.0) following Aria and Cuccurullo (2017), with data processing and visualization performed via Biblioshiny. VOSviewer (version 1.6.20) (van Eck and Waltman, 2010) was used for network construction and clustering. A minimum keyword occurrence threshold of 5 was applied for co-occurrence analysis. Networks were normalized using the association strength method, and clustering was performed using the default Louvain algorithm in VOSviewer. No formal sensitivity analysis was conducted, although preliminary testing of parameter settings indicated stable cluster structures.

RESULTS

Key information

Table 2 presents the descriptive characteristics of the bibliographic dataset on phytogenic feed additives in broiler chickens. The dataset covers the period from 1992 to 2025 and comprises 1,332 documents published across 285 sources. The annual scientific production shows a growth rate of 17.18%, indicating a steady increase in research activity in this field. The average document age was 6.24 years, suggesting that the literature is relatively recent, with strong contemporary research interest. On average, publications received 26.8 citations per document, reflecting moderate to high research impact. The dataset included 13,681 references, 4,891 Keywords Plus, and 2,337 author keywords, indicating broad thematic coverage. A total of 5,528 authors contributed to the literature, with only 20 single-authored papers (approximately 1.5%), highlighting a strong tendency toward collaborative research. Overall collaboration intensity was further supported by an average of 5.94 co-authors per document and an international co-authorship rate of 29.5%. All documents in the dataset were classified as articles (n= 1,332), confirming a homogeneous document type structure.

Annual scientific production trends

Figure 2 illustrates the annual scientific production on phytogenic feed additives in broiler chickens from 1992 to 2025. Scientific output remained very low during the early years of the study period (1992-2004), with only a small number of publications produced annually. From 2005 onward, publication activity increased gradually, followed by a more pronounced growth phase after 2010. A marked acceleration in scientific output was observed from 2018 onward, with publication numbers increasing substantially during 2020-2025, reflecting the growing research interest in phytogenic feed additives as alternatives to antibiotic growth promoters and as tools for improving broiler health and productivity.

 

Table 2: Descriptive characteristics of the bibliographic dataset on phytogenic feed additives in broiler chicken.

Description	Results
Main information of data:
Timespan	1992:2025
Journals Sources	285
Documents	1332
Annual Growth Rate (%)	17.18
Average Document Age (years)	6.24
Average Citations per Document	26.8
Total References Cited	136,812
Document contents
Keywords Plus (ID)	4891
Author's Keywords (DE)	2337
Authors
Authors	5528
Authors of single-authored docs	20
Authors collaboration
Single-authored docs	22
Co-Authors per Doc	5.94
International co-authorships %	29.5
Document types
Article	1332

 

 

The highest publication output was recorded in the most recent years of the dataset, indicating continued expansion of research activity in this field. However, publication counts for 2025 should be interpreted with caution because they represent records available in Scopus at the time of data retrieval and may not reflect the complete annual publication output. No fractional counting was applied; all indexed records were counted as full publications. Therefore, the publication count for 2025 should not be considered a direct measure of the final annual scientific production but rather a snapshot of the database contents at the time of data collection.

 

Most relevant sources

Research on phytogenic feed additives in broiler chickens has been published across a diverse range of poultry, animal science, and veterinary journals, reflecting the interdisciplinary nature of the field (Figure 3). Based on publication output, Poultry Science was the most productive journal, contributing 175 articles, followed by Animals (77 articles) and the Italian Journal of Animal Science (33 articles). Other notable sources included the Journal of Applied Poultry Research (31 articles), Frontiers in Veterinary Science (29 articles), International Journal of Poultry Science (26 articles), and British Poultry Science (25 articles). Additional contributions were provided by Tropical Animal Health and Production (23 articles), Veterinary Medicine and Science (22 articles), Brazilian Journal of Poultry Science (19 articles), Journal of Animal Physiology and Animal Nutrition (18 articles), Pakistan Veterinary Journal (18 articles), Indian Journal of Animal Sciences (17 articles), Animal Production Science (16 articles), and the Journal of the Hellenic Veterinary Medical Society (16 articles).

The dominance of Poultry Science is likely associated with its specialized focus on poultry nutrition, physiology, health, and production, making it a primary publication venue for studies investigating phytogenic feed additives in broiler chickens. Similarly, the high publication output of Animals may reflect its broad scope in animal science and its frequent publication of studies related to nutrition, feed additives, animal health, and production systems. It should be noted that the ranking presented in Figure 3 is based solely on the number of publications and does not incorporate journal impact indicators such as Impact Factor, CiteScore, or h-index. Therefore, publication productivity should not be interpreted as a measure of journal quality or scientific impact. Taken together, the distribution of articles across poultry-specific, animal science, and veterinary journals demonstrates that phytogenic feed additive research encompasses multiple disciplines, including growth performance, digestive physiology, gut health, immunity, and animal health. The potential influence of journal-specific factors, such as special issues or editorial policies, was beyond the scope of the present study and was not evaluated.

 

 

Most productive authors

Figure 4 presents the author’s productivity based on the total number of publications in the dataset. In-Ho Kim and Ilias Giannenas were the most productive authors, each contributing 20 publications. They were followed by Alireza Seidavi (17 publications), Mohamed Abd El-Hack (15 publications), and Yuming Guo (14 publications). Doa Ibrahim, Kyung-Woo Lee, and Ayman Swelum each contributed 13 publications, while Konstantinos Mountzouris, Asghar Abbas, Rifat Ullah Khan, and Sugiharto each produced 11 publications. David Bravo and Mehmet Bozkurt contributed 10 publications each. These findings indicate that research output in this field is concentrated among a relatively small group of highly active researchers. However, the analysis is based on total publication counts and does not differentiate among first, corresponding, senior, or co-authorship positions; therefore, it reflects publication participation rather than individual leadership within the field.

Author citation performance

Citation indicators reveal significant variation among authors and publication periods (Table 3). Hernández demonstrated a major contribution, with a high total citation count (TC = 776) and the highest citations per year (TCpY = 33.74) for the 2004 publication (Hernández et al., 2004). Similarly, Lee showed a strong research impact, with notable citation performance (TC= 501; TCpY = 20.88) in 2003 (Lee et al., 2003). Other influential publications included those by Cross et al. (2007), Hashemipour et al. (2013), and García et al. (2007), which accumulated 467, 431, and 312 total citations, respectively. These studies also exhibited high annual citation rates, with TCpY values of 23.35, 30.79, and 15.60, highlighting their continuing scientific relevance within the field. In addition, consistently strong citation performance was observed for studies by (Giannenas et al., 2003; Jamroz et al., 2005; Choct and Annison, 1992; Yeo and Kim, 1997; Hong et al., 2012), with TC ranging from 220 to 296 and TCpY from 7.37 to 20.82. These findings indicate the presence of frequently cited foundational studies that continue to shape the field.

Affiliations, authors, and country relationships

Figure 5 illustrates the relationships between author affiliations (AU_UN), authors (AU), and the corresponding authors’ countries (AU_CO). Several institutions make a significant contribution to the knowledge base of the phytogenic feed additive topic, with veterinary and agricultural faculties being the most dominant group. Several authors serve as key connectors linking various institutions and countries, indicating strong collaboration. Pakistan emerged as the most prominent corresponding author country, which reflected the substantial and leading contributions evident. Egypt, Saudi Arabia, Iran, the United States, China, and Indonesia also demonstrated prominent representation in the field of phytogenic feed additives. These results highlight the importance of country collaboration and also suggest that research productivity is concentrated around specific institutional and geographic hubs.

 

Table 3: Number of citations (TC) and average citations per year (TCpY) by author for publications on phytogenic feed additives in broiler chickens.

Paper	TC	TCpY
Hernández F, 2004, Poult Sci	776	33.74
Lee KW, 2003, Brit Poult Sci	501	20.88
Cross DE, 2007, Brit Poult Sci	467	23.35
Hashemipour H, 2013, Poult Sci	431	30.79
García V, 2007, J Appl Poult Res	312	15.60
Giannenas I, 2003, Arch Anim Nutr	296	12.33
Jamroz D, 2005, Brit Poult Sci	295	13.41
Lee K-W, 2004, Int J Poult Sci-A	287	12.48
Choct M, 1992, Br J Nutr	262	7.49
Gunal M, 2006, Int J Poult Sci	258	12.29
Du E, 2016, J Animal Sci Biotechnol	229	20.82
Yeo J, 1997, Poult Sci	221	7.37
Hong JC, 2012, Livest Sci	220	14.67

 

TC = Total citations recorded in Scopus; TCpY = Average citations per year since publication.

 

The country’s scientific production

Scientific output at the country level was concentrated in a relatively small number of countries (Figure 6). China was the leading contributor in terms of publication volume, followed by Egypt and Iran. Pakistan, Turkey, and Saudi Arabia also contributed substantially to the literature, while the United States, Indonesia, India, and Brazil maintained moderate but consistent research output. This pattern reflects the geographical distribution of research activity in the field of phytogenic feed additives in broiler chickens. However, these results are based on absolute publication counts and do not account for differences in population size, research expenditure, or scientific workforce among countries. Therefore, the findings should be interpreted as indicators of research volume rather than research productivity or efficiency relative to national resources. Factors such as research priorities, institutional infrastructure, funding availability, and scientific capacity may contribute to the observed distribution of publications across countries.

Country of correspondence of authors

The distribution of corresponding-author countries revealed differences in research leadership patterns and international collaboration intensity (Figure 7). China ranked first in corresponding-author publications with 99 articles (14.4%), followed by Iran with 89 articles. Both countries were dominated by single-country publications (China: SCP= 82; Iran: SCP= 75), indicating strong domestic research capacity and extensive national collaboration networks. In contrast, the United States and Saudi Arabia exhibited high proportions of multi-country publications

 

 

 

(MCP%= 65.5% and 70.8%, respectively), reflecting substantial engagement in international scientific collaboration. Egypt and Pakistan also demonstrated notable levels of international collaboration, with MCP values accounting for 42.6% and 58.3% of their corresponding-author publications, respectively. Meanwhile, Turkey, India, Indonesia, and Brazil were characterized by predominantly single-country publications, suggesting that research activity in these countries remains largely domestically driven. These findings indicate that leadership in publication output and prominence in international collaboration networks are distinct dimensions of scientific activity. While China and Iran led in corresponding-author publication volume, countries such as Saudi Arabia, the United States, and Pakistan showed comparatively stronger levels of international collaboration.

International collaboration networks

The international collaboration network, constructed from co-authorship affiliations among countries, revealed a highly interconnected research landscape characterized by several major collaborative hubs and distinct regional interaction patterns (Figure 8). The numbers in parentheses represent the frequency of collaborative publications between pairs of countries. China emerged as a major collaborative actor, maintaining strong research partnerships with Pakistan (17 collaborative publications), Saudi Arabia (11), the United States (7), Egypt (6), and Indonesia (4). Saudi Arabia also demonstrated extensive international engagement through collaborations with Egypt (31), Pakistan (26), and the United States (7). Pakistan exhibited broad collaborative connections across Asia, the Middle East, and Western countries, highlighting its active participation in international research networks. Egypt maintained strong regional partnerships, particularly with Saudi Arabia and Kuwait, reflecting the importance of regional scientific cooperation. Iran and Italy displayed moderate but balanced collaboration patterns, while the United States served as a global connector through multiple transcontinental partnerships. The network indicates that a relatively small number of countries account for the majority of international collaborations and play central roles in knowledge exchange. In contrast, many countries contribute through more limited collaborative relationships while continuing to support the expansion of research on phytogenic feed additives in broiler chickens.

Keyword analysis and research trends

Keyword analysis revealed the major research themes and evolving conceptualfocus of phytogenic feed additive research in broiler chickens (Figure 9). The most frequently occurring term was “broiler” (343 occurrences),followed by “performance” (115) and

 

 

“growth performance” (107), indicating that production outcomes remain the primary research focus. Among phytogenic-related terms, “essential oils” were one of the most frequently used keywords (64 occurrences), highlighting their importance as a widely investigated feed additive. Research attention to animal health was reflected by keywords such as immunity (41), immune response (27), gut health (21), gastrointestinal health (21), and gut microbiota (20). Keywords related to production challenges, including coccidiosis (35) and heat stress (31), demonstrated growing interest in the role of phytogenic additives under disease and environmental stress conditions. In addition, meat quality (41) indicated that research has expanded beyond growth performance to include product quality attributes. The reported frequencies represent keyword occurrences within the dataset and should be interpreted as indicators of thematic prominence rather than normalized measures of keyword distinctiveness.

Keyword co-occurrence

The co-occurrence network of keywords describes the relationships among the main topics in the research of phytogenic feed additives in broiler chickens (Figure 10). In the VOSviewer network, node size reflects keyword occurrence frequency, whereas links represent co-occurrence relationships among keywords. The colored clusters indicate groups of keywords that frequently appear together and therefore represent related research themes. The term “broiler” was at the center, indicating that it was the primary focus and connected various research topics. The prominent topics, including “essential oils”, “digestibility”, “meat quality”, and “intestinal morphology”, suggested that research continues to focus primarily on chicken performance and physiological responses.

Another topic area (gut health, gut microbiota, immune response, and cecal microbiota) indicated the important role of gut microorganisms in maintaining chicken health. Additionally, topics of disease and stress, such as coccidiosis, Eimeria, and heat stress, were also interconnected, suggesting that phytogenic additives are frequently studied under challenging rearing conditions. Certain compounds (thymol and carvacrol) frequently appeared in the research, which indicates that these compounds are extensively studied as beneficial active ingredients. This pattern indicated that research on broiler chickens incorporates various scientific fields, such as nutrition, microbiology, the immune system, and production performance.

 

 

Evolution of thematic research

The thematic evolution analysis revealed the continuity and gradual diversification of research topics related to phytogenic feed additives in broiler chickens across four analytical periods generated by Biblioshiny (Figure 11). During the initial period (1992–2017), research was primarily centered on broiler, broilers, broiler chicken, phytogenic, performance, and coccidiosis, indicating a strong emphasis on production performance and disease-related challenges. In the subsequent period (2018–2021), the thematic structure expanded to include antioxidant, essential oils, phytobiotic, meat quality, and carcass, reflecting growing interest in the functional properties of phytogenic compounds and their effects on product quality.

During 2022–2023, research themes became more diverse, with the emergence of gut microbiota, immunity, essential oils, poultry, and phytogenic, suggesting increasing attention to biological mechanisms and health-related aspects of phytogenic supplementation. In the most recent period (2024–2025), the dominant themes included growth performance, phytogenic feed additives, essential oils, feed intake, productive performance, and broiler chickens. These themes indicate the continued importance of productivity-oriented outcomes while also reflecting sustained interest in specific phytogenic interventions.

Collectively, the thematic evolution demonstrates a progression from broad performance-focused studies toward more specialized investigations of phytogenic compounds, product quality, and host-related biological responses. However, the analytical periods shown in Figure 11 were generated automatically by Biblioshiny based on the distribution of documents and keywords rather than being manually defined. Therefore, the unequal time intervals should be interpreted as software-generated analytical partitions. Furthermore, because the final period (2024–2025) covers a relatively short timeframe and may be affected by database indexing lag, the identified themes should be considered emerging research directions rather than definitive long-term trends.

Citation structure

An analysis of globally cited documents indicates that a relatively small number of publications have exerted substantial influence on the development of research on phytogenic feed additives in broiler chickens (Figure 12). The study by Hernández et al. (2004) received the most global citations, underscoring its importance as a foundational reference in the field. Similarly, publications by Hashemipour et al. (2013) and Gunal et al. (2006) accumulated considerable citation counts, reflecting their significant contributions to the understanding of broiler nutrition and phytogenic feed additive applications. Several other publications achieved moderate citation levels, suggesting sustained influence within specific research areas. In contrast, many publications received

 

relatively few citations, which may be attributable to their more recent publication dates, specialized research focus, or lower visibility within the broader scientific community. It should be noted that this analysis is based on cumulative citation counts and therefore identifies influential publications over time rather than papers experiencing sudden increases in scholarly attention, as would be assessed through citation burst analysis.

Most cited documents

The citation analysis of the most influential documents based on local citations (LC), global citations (GC), and the LC/GC ratio is presented in Table 4. Local citations reflect the influence of a publication within the phytogenic feed additive research dataset, whereas global citations indicate its broader recognition across the scientific literature. Amad received the highest number of local citations (26) and accumulated 210 global citations, indicating substantial influence both within the field and beyond it (Amad et al., 2011). Abbas exhibited the highest LC/GC ratio (19.23%), suggesting that a relatively large proportion of its citations originated from within the phytogenic feed additive research community, highlighting its strong field-specific relevance (Abbas et al., 2017). In contrast, Hernández received the highest number of global citations (776) but showed (Hernández et al., 2004) a comparatively low LC/GC ratio (0.91%), indicating that its influence extends well beyond the specific field and has been recognized across a broader range of scientific disciplines. Together, these metrics demonstrate that local and global citation indicators provide complementary perspectives on scientific impact, reflecting both field-specific relevance and broader scholarly influence.

DISCUSSION

This bibliometric analysis provides a comprehensive overview of the scientific development of research on phytogenic feed additives in broiler chickens. The results indicate a substantial expansion of the literature over the past three decades, accompanied by increasing diversification of research themes, broader international participation, and the emergence of more specialized areas of investigation. Early studies primarily focused on evaluating the effects of phytogenic additives on growth performance and feed efficiency (Jamroz et al., 2003), whereas more recent research has expanded to include topics such as immunity, oxidative stress, intestinal

 

Table 4: Most cited documents on phytogenic feed additives in broiler chickens.

Paper	Year	Local citations	Global citations	LC/GC ratio (%)
Amad A, 2011, Poult Sci	2011	26	210	12.38
Alçiçek A, 2003, S Afr J Anim Sci	2003	22	197	11.17
Abudabos Am, 2018, J Appl Anim Res	2018	13	112	11.61
Abbas A, 2017, Pak Vet J	2017	10	52	19.23
Abudabos A, 2016, Environ Sci Pollut Res	2016	10	89	11.24
Abbas A, 2023, Pak Vet J	2023	8	51	15.69
Adaszynska SM, 2019, Poult Sci	2019	8	80	10.00
Amerah Am, 2012, Poult Sci	2012	8	63	12.70
Al-Hoshani N, 2023, Pak Vet J	2023	7	58	12.07
Abbas A, 2017, Microb Pathog	2017	7	72	9.72
Hernandez F, 2004, Poult Sci	2004	7	776	0.91
Alp M, 2012, J Appl Poult Res	2012	6	66	9.09
Ertaş On, 2005, Int J Poult Sci	2005	6	163	3.68
Agusetyaningsih I, 2022, Ann Anim Sci	2022	5	33	15.15
Yarmohammadi BS, 2020, Livest Sci	2020	5	82	6.10

 

morphology, and gut microbiota. These trends reflect the growing scientific interest in understanding the broader biological roles of phytogenic feed additives in poultry production (Gadde et al., 2017; Brenes and Roura, 2010).

Developments in scientific research and the maturity of the field

One of the most notable findings of this study is the sustained growth in scientific output related to phytogenic feed additives in broiler chickens. During the early years of the field, publication activity remained relatively limited, reflecting an exploratory phase characterized by the establishment of fundamental concepts and preliminary evaluations of phytogenic compounds. However, publication output increased substantially after 2010 and accelerated further after 2018. This pattern is consistent with the development of a research field that has gained increasing scientific, industrial, and practical relevance.

Several factors may have contributed to this growth. The search for alternatives to antibiotic growth promoters (AGPs), increasing interest in sustainable poultry production, and advances in nutritional and physiological research have all likely stimulated scientific attention toward phytogenic feed additives (Castanon, 2007; Dibner and Richards, 2005). Nevertheless, it is important to note that the present bibliometric analysis cannot directly establish causal relationships between publication trends and regulatory developments. Therefore, the observed increase in research activity should be interpreted as reflecting growing international interest in phytogenic feed additives rather than evidence of a universal transition toward AGP-free production systems.

The apparent decline in publication output during the most recent year should also be interpreted cautiously. Because data collection included recent publications, the lower number of records may reflect incomplete database coverage and indexing lag. However, this explanation was not formally tested in the present study and therefore should be regarded as a possible rather than a confirmed factor. Overall, the long-term publication trend indicates that phytogenic feed additive research remains an active and expanding area within poultry nutrition and animal science.

Current state of the knowledge base and citation dynamics

The relatively recent average publication age, combined with substantial citation activity, suggests that phytogenic feed additive research continues to attract considerable scientific attention. Citation analyses revealed a highly uneven distribution of influence, with a relatively small number of publications accounting for a substantial proportion of citations. Such patterns are common in scientific fields, where foundational studies often serve as key references that shape subsequent research directions, experimental designs, and methodological approaches (Cobo et al., 2011).

Highly cited publications identified in this study appear to have contributed significantly to the development of phytogenic research by providing evidence regarding efficacy, biological responses, and potential mechanisms of action. However, it is important to recognize that the present analysis did not classify studies according to their research design or compare citation performance among different categories of publications. Consequently, the results do not permit a direct conclusion that mechanistic studies receive more citations than descriptive studies. Instead, citation counts should be interpreted as indicators of scholarly influence rather than evidence of the specific factors responsible for citation accumulation.

Furthermore, lower citation counts among recent publications should not be interpreted as evidence of limited importance or scientific value. Citation accumulation is a time-dependent process, and recently published studies have had fewer opportunities to be cited than older publications. Therefore, citation indicators should always be interpreted within the temporal context of publication history.

Performance-oriented research and emerging biological themes

Keyword occurrence and thematic analyses demonstrated that growth performance remains the dominant research theme within the field. Keywords such as performance, growth performance, and related production indicators occurred most frequently throughout the dataset, highlighting the continuing importance of productivity outcomes in broiler nutrition research.

At the same time, the bibliometric results indicate the emergence of additional research themes related to health and physiological responses. Keywords including immunity, immune response, gut health, gut microbiota, and intestinal morphology appeared less frequently than performance-related terms but were consistently represented in thematic clusters and recent research developments. Because these keywords occurred in a relatively small proportion of the total dataset, they should be interpreted as emerging rather than dominant research themes.

The growing presence of these health-related topics suggests that researchers are increasingly interested in understanding how phytogenic additives interact with physiological processes beyond growth performance alone. This trend reflects a broader perspective on poultry nutrition in which productivity, health status, and physiological function are considered interconnected components of production efficiency. However, the bibliometric evidence indicates that performance-related outcomes remain the principal focus of the field.

Gut health, immunity, and microbiota as emerging research areas

Research related to gut health, immunity, and microbiota has gained increasing visibility within the scientific literature, although these topics remain secondary to performance-oriented research. The occurrence frequencies of keywords such as gut health and gut microbiota were relatively modest compared with production-related terms, indicating that these subjects have not yet become dominant themes within the field.

Nevertheless, their appearance within recent thematic structures suggests growing scientific interest in the relationship between phytogenic additives and the physiological functions of the digestive system. This development is consistent with broader advances in animal nutrition research, where interactions among nutrition, intestinal function, immune responses, and microbial communities are increasingly recognized as important components of animal performance and health.

Similarly, keywords related to oxidative stress and antioxidant activity indicate increasing attention to physiological resilience and health maintenance under production challenges. These developments suggest an expansion of research objectives rather than a replacement of traditional performance-focused investigations.

Collaborative structures and global research networks

The collaboration analyses revealed a highly interconnected research community characterized by extensive co-authorship and international cooperation. The presence of large collaborative networks highlights the multidisciplinary nature of phytogenic feed additive research, which integrates expertise from animal nutrition, veterinary medicine, microbiology, physiology, and agricultural sciences.

Country-level analyses showed that publication output was concentrated in a relatively small number of countries, particularly China, Egypt, Iran, and Pakistan. This geographical concentration may reflect differences in poultry industry size, research capacity, funding availability, and institutional infrastructure. However, the present study did not evaluate these factors directly; therefore, such interpretations should be considered contextual observations rather than causal conclusions.

The collaboration network further demonstrated that publication productivity and international collaboration represent distinct dimensions of scientific activity. While some countries contributed a high volume of publications through strong domestic research systems, others relied more heavily on international partnerships. These findings emphasize the importance of global collaboration in facilitating knowledge exchange, methodological development, and the dissemination of scientific findings across diverse production environments and geographic regions.

Thematic specialization and intellectual structure

The thematic analyses revealed a field characterized by both continuity and diversification. Growth performance remained the central theme throughout the study period, reflecting its enduring importance in broiler production research. At the same time, specialized topics related to phytogenic compounds, intestinal function, immunity, and health-related outcomes emerged as increasingly visible components of the research landscape.

The thematic evolution analysis suggests a gradual broadening of research interests rather than abrupt shifts in scientific focus. However, interpretation of the most recent thematic period should be approached with caution because it covers a relatively short timeframe and may be influenced by incomplete database indexing. Consequently, the themes identified in the latest period are best viewed as emerging directions rather than definitive indicators of future research priorities.

Implications for future research

The bibliometric findings suggest several directions for future research. First, the continued expansion of health-related themes indicates opportunities for deeper investigation of the physiological mechanisms associated with phytogenic feed additives. Second, the variability in phytogenic sources, formulations, dosages, and experimental conditions highlights the importance of improved standardization and reporting practices to enhance comparability among studies.

Third, the increasing complexity of research themes underscores the value of multidisciplinary approaches that integrate nutrition, physiology, microbiology, and veterinary science. Although advanced methodologies such as transcriptomics, metabolomics, and other omics-based approaches were not prominent within the keyword dataset, these techniques may offer valuable opportunities for future mechanistic investigations. Therefore, their mention should be regarded as a potential future direction rather than evidence of an existing research trend.

Finally, the growth of international collaboration networks suggests that cross-national research initiatives may play an increasingly important role in addressing variations among production systems, environmental conditions, and management practices. Such collaborations can enhance the generalizability and applicability of future research findings and contribute to a more comprehensive understanding of phytogenic feed additives in broiler production systems.

CONCLUSION

This bibliometric analysis mapped the scientific landscape of research on phytogenic feed additives in broiler chickens from 1992 to 2025 and revealed a sustained expansion of scientific activity, increasing international collaboration, and growing thematic diversification. Growth performance remains the dominant research theme, reflecting its central importance in broiler production. However, emerging topics related to immunity, intestinal health, gut microbiota, and physiological responses indicate a gradual broadening of research interests beyond conventional productivity outcomes.

The analysis also demonstrated that scientific contributions are concentrated within a relatively small number of countries, institutions, authors, and journals, highlighting the importance of collaborative networks in shaping the development of the field. Furthermore, citation and thematic analyses identified influential publications and evolving research clusters that form the intellectual foundation of current phytogenic feed additive research.

Beyond summarizing existing knowledge, this study provides a quantitative overview of research trends, collaboration structures, and thematic developments that are difficult to capture through traditional narrative reviews. The findings suggest that future research would benefit from greater standardization of phytogenic additive characterization, improved reporting practices, and stronger integration of multidisciplinary approaches to better understand the mechanisms underlying phytogenic responses in broiler chickens.

This study offers a reference framework for researchers seeking to identify influential studies, emerging themes, collaboration opportunities, and knowledge gaps that may guide future investigations in phytogenic feed additive research.

Acknowledgement

The authors sincerely acknowledge the Department of Animal Nutrition and Feed Technology, Faculty of Animal Science, IPB University, and the Center for Tropical Animal Studies (CENTRAS), IPB University, Bogor, Indonesia, for providing academic support and research facilities that facilitated the completion of this bibliometric study. The authors also appreciate the valuable contributions of researchers whose published works formed the basis of this analysis. Their efforts have significantly advanced scientific knowledge on phytogenic feed additives and broiler nutrition.

NOVELTY STATEMENT

This study presents the first comprehensive bibliometric analysis of phytogenic feed additives in broiler nutrition, systematically mapping global research trends, key contributors, and evolving thematic structures. It goes beyond traditional reviews by revealing emerging research frontiers and critical gaps, particularly in relation to precision nutrition, omics integration, and sustainable poultry production. The findings provide a strategic knowledge framework to guide future research and innovation in antibiotic-free broiler systems.

AUTHOR’S CONTRIBUTION

Rita Mutia: Conceptualization, data curation, formal analysis, visualization, writing original, and draft preparation; Muhammad Ridla: Conceptualization, methodology, supervision, validation, and writing, review and editing; Arif Darmawan: Data curation, software, investigation, and writing, review and editing. All authors have read and approved the final manuscript.

Generative AI and AI-assisted technology statement

The authors declare that generative AI tools were used solely to assist in language editing and improving the clarity of the manuscript. All scientific content, data analysis, interpretation, and conclusions were developed independently by the authors. The authors take full responsibility for the accuracy, integrity, and originality of the work.

Conflict of interest

The authors have declared that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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