The Potential of Plant By-Products as the Agents to Reduce Emissions: Study Case on Farmer’s Perspectives in South Sulawesi, Indonesia

South Sulawesi Province holds a geographically strategic position that makes it an essential region for economic, cultural, and logistical activities within Indonesia and Southeast Asia. Its central location in the Indonesian archipelago places it at the intersection of major maritime and terrestrial trade routes, linking the western and eastern parts of the country [1]. This strategic advantage enhances its role as a transit hub for goods, services, and people, contributing significantly to national development.

The utilization of horticultural plant by-products as Phyto-biotic agents to mitigate greenhouse gas emissions presents a novel and sustainable approach to addressing environmental challenges in South Sulawesi's livestock sector. As a region with a rich agricultural base, South Sulawesi produces significant quantities of horticultural crops, such as sweet potatoes, cassava, bananas, and moringa. These crops generate by-products, including leaves, stems, and peels, that are often discarded or underutilized [2, 3]. These by-products are rich in bioactive compounds with potential applications as natural feed additives, particularly in reducing enteric methane emissions from ruminants.

This study was located in the regency of Bone, province of South Sulawesi. Bone Regency, also known as 'Bumi Arung Palakka,' is one of the regencies in South Sulawesi Province, which serves as a center for the development of beef cattle. It spans a total area of 4,559.0 km² with a population of 801,775 individuals, yielding an average population density of 162 people/km². Bone Regency comprises 27 districts and is strategically located, further enhanced by the presence of Bajoe Port connecting it to other provinces, thereby making Bone Regency significant in trade, services, and livestock in the Eastern Indonesia region [4]. The distance from Bone Regency to Makassar, the provincial capital of South Sulawesi, is approximately 3 hours. Based on statistical data from Bone Regency, beef cattle are the most populous ruminant livestock, with a population of 436,363 heads in 2022, slightly lower by 0.04% compared to the previous year, 2021, which recorded 452,347 heads. Despite this slight decline, Bone Regency retains the distinction of having the largest population of beef cattle among regencies in South Sulawesi. However, it becomes a concern, as increasing the population of cattle has been the target of the ministry of agriculture and the increase amount of emissions from cattle is in line with the increase in the number of cattle [5]. It is necessary to find a proper solution for the sustainability of cattle farm.

Bone Regency is rich in bio-pharmaceutical plants, which can be utilized as feed additives for beef cattle to enhance their appetite and strengthen their immune system, particularly during transitional seasons. The application of bio-pharmaceutical plants in ruminant livestock management serves as a strategy to reduce antibiotic usage, as improved immune resilience is expected to protect livestock from pathogenic microorganisms, especially when combined with continuous sanitation practices in the farming environment. The use of bio-pharmaceutical plants as Phyto-biotics in beef cattle production not only benefits the livestock but also contributes to environmental sustainability.

Incorporating horticultural by-products as Phyto-biotics offers multiple benefits. Economically, it provides a value-added use for agricultural waste, reducing the reliance on expensive commercial feed additives. This can lower feed costs and increase the profitability of livestock farming. Environmentally, the practice contributes to mitigating the environmental footprint of ruminant livestock, which is a significant source of methane emissions—a potent greenhouse gas [6]. By repurposing agricultural residues, this approach also aligns with principles of circular economy and sustainable resource management, making it a model for climate-smart agriculture in Indonesia.

The use of herbal remedies in beef cattle farming systems has gained increasing attention as an alternative approach to enhancing livestock health and productivity. Herbal remedies, which consist of various bio-pharmaceutical plants such as turmeric (Curcuma longa), ginger (Zingiber officinale), Javanese ginger (Curcuma xanthorrhiza), and betel leaf (Piper betle), contain bioactive compounds that function as immunostimulants, antioxidants, and natural antimicrobial agents [7, 8].

Farmers' understanding of formulating herbal remedies is a crucial aspect in supporting the sustainable health and productivity of beef cattle. With proper utilization, herbal remedies can serve as a natural solution to improving livestock immunity, optimizing digestion, and reducing dependence on antibiotics.

This study aimed to: 1). assess the level of awareness and understanding among farmers in two districts in Bone Regency, South Sulawesi regarding the utilization of plant by-products as natural feed additives (Phyto-biotics) and their potential role in mitigating greenhouse gas emissions, as Bone Regency is the main beef cattle supplier for eastern Indonesia; and 2). investigate farmers’ perspectives on the potential benefits, challenges, and feasibility of incorporating plant by-products into livestock feeding practices. In the future, this study will be useful for recommendations for integrating plant by-products into livestock feeding strategies, tailored to the socio-economic and ecological context of South Sulawesi, to promote sustainable and low-emission agriculture.

The findings of this study indicated varying levels of awareness and understanding among farmers in the two selected districts in Bone Regency (Tanete Riattang and Tanete Riattang Timur) regarding the utilization of plant by-products as natural feed additives (Phyto-biotics) and their potential role in mitigating greenhouse gas emissions. While the concept of using Phyto-biotics for environmental benefits was relatively unfamiliar to most respondents, there was a significant awareness of using specific plant by-products, particularly ginger, as a feed additive to enhance palatability and livestock appetite.

Some recent studies have reported the success use of the individual herbal plants as methane reduction agents in cattle farming. Various plant-based feed additives, including turmeric, ginger, and lemongrass, have demonstrated potential in mitigating enteric methane emissions by modulating rumen fermentation, inhibiting methanogens, and enhancing alternative hydrogen utilization pathways [9]. Turmeric (Curcuma longa) is a widely studied medicinal plant known for its curcuminoids and essential oils, which exhibit antimicrobial, anti-inflammatory, and antioxidant properties. The primary bioactive compound in turmeric, curcumin, disrupts methanogen membrane integrity, thereby reducing their population in the rumen Additionally, curcumin shifts ruminal fermentation toward propionate production, a pathway that competes with methanogenesis for hydrogen utilization. By enhancing microbial diversity and stimulating fibrolytic bacteria, turmeric supplementation improves volatile fatty acid (VFA) profiles, which are essential for nutrient absorption and energy efficiency. The inclusion of 1.5% turmeric powder in cattle feed resulted in a 15-20% reduction in methane emissions, along with improved feed efficiency and immune function.

Ginger (Zingiber officinale) contains a variety of bioactive compounds, including gingerol, shogaol, and zingerone, which exhibit antimicrobial and anti-inflammatory properties. These compounds directly inhibit methanogenic archaea by interfering with their enzymatic activity, thereby reducing methane production [10]. Additionally, ginger promotes non-methanogenic fermentation pathways by increasing succinate and propionate synthesis, which serve as alternative hydrogen sinks. Another crucial mechanism of action is the modulation of fiber degradation rates; ginger slows down cellulose fermentation, leading to a more controlled release of fermentation gases [11]. Research conducted in Central Java involving the supplementation of dairy cattle diets with 2% ginger powder demonstrated an 18-22% reduction in methane emissions, along with improved milk fat content and overall gut health [12].

Lemongrass (Cymbopogon citratus), a tropical grass rich in citral, limonene, and polyphenols, has also been identified as an effective natural feed additive for methane reduction. Citral and limonene possess strong antimicrobial properties, which directly inhibit methanogenic archaea, thereby reducing the hydrogen-dependent formation of methane [13] . Furthermore, lemongrass modulates fermentation pathways by increasing the proportion of acetate and propionate, leading to more efficient energy metabolism. Studies conducted on Bali cattle farms, where lemongrass extract was incorporated at 1.8% of total dry matter intake (DMI), revealed a 25% decrease in methane emissions, coupled with improved feed conversion efficiency and resistance to gastrointestinal infections [14].

When used in combination, turmeric, ginger, and lemongrass exhibit synergistic effects, enhancing methane reduction through complementary mechanisms. Turmeric primarily targets methanogen suppression and hydrogen redirection, ginger modifies fiber degradation rates and fermentation kinetics, while lemongrass provides direct antimicrobial effects on methanogens and enhances overall rumen balance. In vivo experimental trial in beef cattle farm demonstrated that supplementing cattle diets with a mixture of turmeric (1%), ginger (1%), and lemongrass (1%) resulted in a 30-35% reduction in methane emissions without compromising feed digestibility [15].

In order to reduce the environmental impact from burning the by-product of sweet potato, it is necessary to utilize this as feed component for cattle. Some studies have reported the secondary compounds of this sweet potato by-product that is potential as methane reduction agent. Additionally, sweet potato by-product still have good nutritional values. Both the tubers and vines of sweet potato contain valuable bioactive compounds, including phenolic compounds, flavonoids, and resistant starch, which can influence rumen fermentation patterns and reduce enteric methane emissions. One of the primary ways sweet potato contributes to methane mitigation is through its high starch and low fiber composition. Unlike conventional roughage-based feeds, sweet potato tubers are rich in non-structural carbohydrates (NSC), particularly starch, which promotes propionate fermentation pathways in the rumen. The propionate pathway competes with methanogenesis for hydrogen (H₂) utilization, thereby reducing the availability of substrates for methane-producing archaea. Studies have shown that feeding high-starch diets, including sweet potato tubers, can lower methane emissions by up to 20-30% compared to high-fiber diets [16, 17] Additionally, the presence of resistant starch in sweet potato slows down fermentation, leading to a more controlled release of gases and a shift toward less methane-intensive fermentation end products [18].

Sweet potato vines, a by-product of tuber production, also exhibit methane mitigation potential due to their rich polyphenol and flavonoid content. Polyphenols, such as chlorogenic acid and anthocyanins, have been reported to possess antimicrobial properties that selectively inhibit methanogenic archaea in the rumen. The mechanism behind this suppression involves the disruption of coenzyme methyltransferase, an essential enzyme in methane synthesis. Research has indicated that feeding sweet potato vines at 15-20% of the total DMI can lead to a 12-18% reduction in methane production while maintaining or even improving fiber digestibility [16, 19].

Furthermore, the high beta-carotene content in sweet potato, particularly in orange-fleshed varieties, can indirectly contribute to methane reduction by enhancing rumen microbial balance and animal health. Beta-carotene is a precursor to vitamin A, which plays a crucial role in immune function and rumen epithelial integrity. A well-functioning rumen environment ensures optimal microbial activity, reducing the risk of dysbiosis, which can otherwise promote excessive hydrogen accumulation—a key precursor to methane synthesis. Additionally, sweet potato supplementation has been linked to improved feed conversion efficiency, meaning that cattle require less feed to achieve similar or greater weight gain, further contributing to a lower carbon footprint per unit of beef or milk produced. The integration of sweet potato into cattle feeding strategies aligns well with circular agriculture and sustainable farming systems. In regions where sweet potatoes are cultivated as a staple food crop, the utilization of by-products such as vines and unmarketable tubers can serve as an economically viable and environmentally friendly livestock feed. This dual benefit supports low-emission livestock production while promoting resource efficiency in mixed farming systems.

The majority of farmers demonstrated a limited understanding of the broader concept of Phyto-biotics and their environmental implications, reflecting a knowledge gap about the role of bioactive compounds in mitigating methane emissions. This is often constrained by a lack of access to technical information and training. In contrast, a minority of respondents showed a basic understanding of Phyto-biotics, often associating them with traditional practices rather than modern scientific approaches.

Interestingly, a significant proportion of farmers were familiar with the use of ginger (Zingiber officinale) as a feed additive, primarily to improve feed palatability and stimulate livestock appetite. However, they use this as individual substrate on the basis of their experience (traditional knowledge) of using ginger as herbal for human and they use this without knowing the proper dose. The farmers’ application of ginger was largely limited to its immediate effects on feed intake, with little awareness of its secondary benefits, such as antimicrobial properties or potential reductions in ruminal methane production.

The variation in awareness levels between the two districts may be attributed to differences in access to agricultural extension services, exposure to innovation, and the educational background of the farmers. Districts with closer proximity to agricultural institutions or markets may benefit from greater dissemination of knowledge about advanced feeding practices, whereas more remote districts might rely predominantly on traditional methods. The prevalent use of ginger highlights an entry point for introducing the concept of Phyto-biotics to farmers. Extension programs and agricultural advisors can leverage farmers’ familiarity with ginger to demonstrate its additional benefits, such as antimicrobial activity and methane reduction potential, thereby bridging the gap between traditional practices and scientific innovations [20]. Furthermore, the integration of other locally abundant plant by-products with similar properties, such as cassava or sweet potato leaves, could enhance the economic feasibility of adopting Phyto-biotics at scale. Sustaining the livestock sector is a way to elevate the sustainability for food supply [21].

Although extensive research has highlighted the benefits of herbal remedies in livestock farming, their implementation at the farmer level still encounters several challenges. One of the primary issues is the lack of knowledge regarding proper dosage and formulation. Farmers often struggle to determine the appropriate amount of herbal additives, which is crucial to avoiding negative effects. An overdose may disrupt metabolic functions in cattle, while an insufficient dosage may fail to deliver the intended health benefits. Additionally, the variability in the phytochemical composition of herbal plants poses another challenge [22]. Factors such as soil type, climate conditions, and cultivation methods can influence the concentration of bioactive compounds, making it essential for farmers to understand proper storage and processing techniques to maintain their efficacy. Moreover, the absence of standardized protocols in herbal remedy preparation further complicates their use [23]. Without uniform guidelines, different farmers may achieve inconsistent results, reducing the reliability of herbal treatments. To address these issues, further research is needed to develop standardized, scientifically validated formulations that ensure both effectiveness and safety in livestock applications.

The limited adoption of Phyto-biotics in cattle feed among farmers is influenced by a combination of economic, technical, informational, and infrastructural barriers. From an economic perspective, Phyto-biotics often entail a higher initial investment compared to conventional feed additives, making them less attractive to farmers operating under financial constraints. The cost-benefit trade-off is a critical determinant in decision-making, as many smallholder farmers prioritize short-term economic viability over long-term sustainability. Studies indicate that financial limitations significantly hinder the adoption of innovative feed technologies, as farmers often lack access to credit or subsidies that could mitigate the initial costs [24]. Without clear and immediate economic incentives, the perceived financial risk associated with Phyto-biotic adoption discourages widespread implementation.

Furthermore, the lack of technical knowledge presents a significant impediment to adoption. The effective utilization of Phyto-biotics requires an understanding of appropriate dosages, feeding strategies, and their interactions with other dietary components. Many farmers, particularly in developing regions, have limited access to structured training programs or extension services that provide this specialized knowledge. Knowledge gaps in livestock nutrition and feeding practices prevent the widespread adoption of alternative feed additives, including Phyto-biotics. This results in uncertainty regarding efficacy and proper application, thereby reinforcing resistance to change [25].

In addition to technical limitations, a lack of awareness regarding the potential benefits of Phyto-biotics further constrains their adoption. Farmers may not fully understand the role of these natural additives in improving cattle health, enhancing feed efficiency, and reducing environmental emissions. This issue is exacerbated by inadequate dissemination of scientific research through extension programs, agricultural cooperatives, and governmental initiatives [26]. Without targeted awareness campaigns and evidence-based demonstrations, farmers may not be able to recognize the long-term advantages of Phyto-biotics. Additionally, infrastructural challenges play a crucial role in limiting accessibility to Phyto-biotic feed additives. The supply chain for these products is often underdeveloped in rural areas, where distribution networks, transportation, and storage facilities are inadequate. As a result, farmers face difficulties in procuring Phyto-biotics consistently, which discourages their integration into feeding systems. The lack of a stable supply chain and reliable market access further diminishes the feasibility of adopting Phyto-biotics on a large scale [25]. To address these challenges, a comprehensive approach is necessary, integrating economic incentives, capacity-building initiatives, awareness programs, and infrastructure development. Policymakers, researchers, and industry stakeholders must collaborate to provide financial support mechanisms such as subsidies or credit schemes, enhance extension services for knowledge dissemination, and invest in supply chain improvements. By overcoming these barriers, the adoption of Phyto-biotics in cattle feed can be significantly improved, leading to enhanced livestock productivity, reduced environmental impact, and greater sustainability in the livestock sector.

It is necessary to enhance farmers' knowledge and application through various strategic measures to optimize the utilization of herbal remedies in livestock production. One fundamental approach is the implementation of scientific-based training and mentoring programs. Government agencies, academic institutions, and livestock extension specialists should facilitate regular training sessions to educate farmers on the classification of herbal plants, extraction techniques, formulation methods, and appropriate dosage administration for beef cattle. Additionally, the integration of technology in the formulation and processing of herbal remedies can significantly enhance the stability and bioavailability of active compounds. The application of simple yet effective technologies, such as fermentation and hot-water extraction, can improve the efficacy and shelf-life of herbal preparations administered to livestock [10, 27]. Collaborative efforts with research institutions and universities are crucial in advancing the scientific validation and standardization of herbal remedies. Strengthening synergies between farmers, researchers, and academic experts will facilitate the development of evidence-based herbal formulations while ensuring compliance with livestock health and safety standards.

The Indonesian government has regulated the use of feed additives, including those derived from herbal ingredients, through various regulations issued by the Ministry of Agriculture. These regulations aim to ensure that all feed ingredients used in the livestock industry meet established safety and quality standards.

One of the key regulations is Minister of Agriculture Regulation No. 22 / Permentan / PK.110 / 6 / 2017 on Feed Registration and Distribution. This regulation sets out the technical and administrative requirements that feed producers, including those producing herbal-based feed, must meet before their products can be registered and marketed in Indonesia [28]. Government Regulation No. 26 of 2021 on the Implementation of the Agricultural Sector replaces Government Regulation No. 78 of 1992 on Veterinary Drugs. This regulation includes provisions regarding minimum technical and quality standards for feed, including the use of additives such as herbal ingredients in livestock feed [29]. The objective is to ensure that all feed additives, including herbal-based ones, comply with the established standards to guarantee animal health and the safety of animal-based food products for consumers.

Governmental policies and incentives play a fundamental role in facilitating the adoption of Phyto-biotics in livestock production by addressing financial, technical, infrastructural, and regulatory barriers that hinder their widespread implementation. One of the primary economic constraints faced by farmers is the higher initial cost associated with Phyto-biotic-based feed additives compared to conventional alternatives. To mitigate this challenge, policymakers can introduce targeted financial interventions such as direct subsidies, tax exemptions, and low-interest credit schemes, thereby enhancing the affordability and accessibility of Phyto-biotics. By reducing the cost burden on farmers, these financial mechanisms can incentivize the transition from synthetic additives to phytogenic compounds, contributing to more sustainable livestock production systems [24].

Beyond financial interventions, the lack of technical knowledge among farmers regarding the efficacy, appropriate dosage, and application of Phyto-biotics remains a critical impediment to their adoption. In this regard, government-supported extension services, training programs, and knowledge dissemination initiatives are essential in bridging the existing knowledge gap. The implementation of farmer field schools, demonstration farms, and mobile advisory units can facilitate experiential learning and practical exposure, allowing farmers to observe firsthand the benefits of Phyto-biotics in enhancing livestock health, improving feed efficiency, and mitigating environmental impacts. Moreover, investments in publicly funded research can strengthen the scientific basis for Phyto-biotic use by generating empirical evidence on their effectiveness, mode of action, and potential synergies with locally available feed resources. Collaboration between research institutions, universities, and government agencies can further support the development of region-specific Phyto-biotic formulations tailored to the nutritional requirements of different livestock species, ensuring their practical applicability in diverse production systems. Infrastructure development is another crucial aspect that influences the adoption of Phyto-biotics, particularly in rural and remote areas where logistical constraints limit farmers' access to innovative feed additives [30, 31]. Government interventions aimed at improving supply chain efficiency, enhancing transportation networks, and investing in feed processing and storage facilities can facilitate the consistent availability of high-quality Phyto-biotics in the market. Policies that promote domestic production of Phyto-biotics from locally sourced plant materials can further strengthen supply chain resilience while reducing reliance on costly imports. By fostering a conducive regulatory environment that supports Phyto-biotic standardization, certification, and quality assurance, governments can build farmer confidence in these feed additives and prevent the proliferation of substandard or adulterated products in the market.

Regulatory policies also play a pivotal role in shaping the adoption trajectory of Phyto-biotics, particularly in the context of antimicrobial resistance (AMR) mitigation and climate change adaptation. The progressive phasing out of antibiotic growth promoters (AGPs) in livestock production, as mandated by regulatory frameworks in many countries, creates an opportunity for Phyto-biotics to serve as natural alternatives [32]. Governments can reinforce this transition by integrating Phyto-biotic adoption into national antimicrobial stewardship programs and providing incentives for farmers who comply with antibiotic reduction targets. Furthermore, given the increasing global emphasis on reducing livestock-related methane emissions, Phyto-biotic-based feeding strategies can be incorporated into national climate policies and sustainable agriculture initiatives. The implementation of carbon credit schemes, wherein farmers utilizing Phyto-biotics to reduce methane emissions receive financial incentives, can serve as an innovative policy mechanism to align environmental objectives with economic incentives.