Enhancing reproduction efficiency in breeding boars using medicinal plants

1 Introduction

Profitability and sustainability of meat supply are important aspects of modern pig agriculture. They are highly influenced by reproductive efficiency (Vlaicu et al., 2024). Farming enterprises face low conception rates, lengthy farrowing intervals, small litter sizes, and inadequate boar fertility despite improvements in breeding technologies and veterinary treatments. Low spermatozoa numbers and quality are linked to almost 90% of male fertility cases (Ezirim et al., 2019). In the past, pharmaceutical treatments and synthetic hormones such as gonadotropin-releasing hormone (GnRH) and porcine luteinising hormone (LH) were used to address these challenges (Knox, 2015). While effective, these methods are frequently accompanied by economic, health, and environmental concerns, such as hormone residues in animal products. Natural, sustainable, and health-friendly solutions are therefore acutely needed. Due to their enormous potential as natural substitutes for artificial chemicals, research into medicinal plants in livestock production has accelerated (Nantapo and Marume, 2022). Medicinal plants, which are rich in bioactive compounds such as polyphenols, flavonoids, alkaloids, terpenoids, and saponins, offer the potential for a comprehensive approach to enhancing reproductive health (Anand et al., 2019). These compounds can enhance spermatozoa quality, reduce oxidative stress (OS), maintain the integrity of reproductive organs, and regulate endocrine processes (Noh et al., 2020).

In comparison to synthetic medications often target specific hormonal pathways, medicinal plants can greatly influence the reproductive system, often with few adverse effects (Zeng et al., 2022). Additionally, the use of medicinal plants supports sustainable animal production practices. Furthermore, small-scale farmers in developing regions, where access to expensive veterinary pharmaceuticals may be limited, find medicinal plants more beneficial due to their affordability and ease of use (Gabriel et al., 2022). Any group of infertile animals is expected to have a high degree of seminal OS since high OS has been associated with infertility (Wu et al., 2020). Cell damage in semen may result from an imbalance between the generation of reactive oxygen species (ROS) and antioxidant scavenging activities (Viudes-De-Castro et al., 2015; Jimoh and Ewuola, 2018). While the use of antibiotics is being regulated due to their detrimental effects on animals, residues in animal products, and the emergence of antibiotic resistance, the use of medicinal herbs is expanding rapidly due to their benefits for food safety (Omokore and Alagbe, 2019). Phyllanthus amarus, Viscum album, and Moringa oleifera have great medicinal potential that can improve performance (Daramola et al., 2018). In comparison to regularly utilised traditional feeds, they contain minimal protein content, acceptable carbohydrates, rich nutrients, antioxidants, and tannins. The inclusion of many substances in a single plant produces complementary favourable effects on how animals perform (Meradi et al., 2022). Some herbs boost spermatogenesis, desire, sexual behaviour, and the success of mating. Some herbs, however, ensure that follicle-stimulating hormone (FSH), LH, and testosterone in the male and female reproductive axes are balanced (Ajuogu et al., 2018). There is a need to promote the adoption of natural reproductive enhancers to serve as a platform for future innovation and policy development in animal reproduction. Therefore, this review aims to provide a perspective on utilising medicinal plants to enhance reproductive efficiency in pigs.

2 Methodology

A literature search was conducted from 2003 to 2026 to identify peer-reviewed and published papers on the measures of reproduction efficiency in boars, reproductive challenges, and current strategies, and medicinal benefits of hempseed (Cannabis sativa L), Allium sativum, Moringa oleifera, and Origanum vulgare, and their influence on reproduction efficiency in breeding boars. Google Scholar, ScienceDirect, ResearchGate, books, and the open-access journal directory were used to obtain published papers. Spermatozoa quality, garlic, oregano, moringa, hemp, fertility, pigs, and oxidative stress were among the search keywords used. Additionally, other relevant articles or documents were located using the citations found in the articles. The following criteria were used to evaluate and sort the searched articles: (I) the corresponding year of publication; (II) the document being published in a peer-reviewed journal or book; (III) the subject serving as a focus point; and (IV) the article or section being about the medicinal properties of all four medicinal plants. The application of these search criteria identified 18,300 relevant studies covering medicinal plant extracts and boar reproductive performance. Furthermore, full versions of these papers were reviewed, assessed, and classified according to the inclusion and exclusion criteria. Non-English authored and published research, research that did not address the effects of the four medicinal plants on animal reproduction, and studies focused on human subjects were rejected. The publications included met the following criteria: (I) effect of hempseed (Cannabis sativa L.), Allium sativum, Moringa oleifera, and Origanum vulgare on reproductive performance, (II) influence on spermatozoa quality, and (III) effect on oxidative stress. Exactly 164 papers met the selection requirements.

3 Measures of reproduction efficiency in boars

Ejaculates semen from boars should consistently contain large volumes of high-quality spermatozoa (Flowers, 2022). The properties of these ejaculates are mostly determined by the size and function of the Sertoli cell population. Development of Sertoli cells continues for weeks after birth and is most active throughout the middle to late stages of foetal development (O'Donnell et al., 2017). A protracted supplementary phase of Sertoli cell development, lasting 6 to 10 weeks, follows this early phase (Ma et al., 2016). Following puberty, testes start to produce cycles of spermatozoa at a consistent pace, and when the germ cells are moved into the cauda epididymis, the boars become fertile within another 5–8 weeks (Das et al., 2023). Therefore, when semen ejaculates contain a small number of low-quality spermatozoa, it is likely that problems develop throughout embryonic development phases.

3.1 Semen quality

Semen quality is a key indicator of male fertility and is assessed based on ejaculate volume, spermatozoa motility, morphology, and concentration, as shown in Figure 1, where semen is analysed. Good spermatozoa motility and normal morphology are crucial for successful fertilisation in artificial insemination programmes (AI) (Guahmich et al., 2023). In addition, early detection of sub-fertile boars is another benefit of routine semen evaluation.

3.2 Libido and mating behaviour

Boar libido has a direct impact on the success of natural mating and the effectiveness of AI semen collection (Cieleń and Sell-Kubiak, 2024). Boars with a high libido produce better-quality semen and have higher fertility rates (Hodel et al., 2021). Moreover, libido can be improved with effective training and management during semen collection, where proper handling and positive reward tactics reduce stress and improve semen quality (Laule, 2024).

3.3 Fertility rate

Boar fertility is influenced by age, genetic makeup, health status, and nutrition (Cieleń and Sell-Kubiak, 2024). Genetic background influences boar reproductive traits, with heritability estimates for spermatozoa quality characteristics ranging from low to moderate (Sá et al., 2025). Selection for boar fertility has historically lagged growth rate and feed efficiency. Modern breeding programmes increasingly include semen quality and fertility indices in boar selection criteria (Llavanera, 2024). Boars are sensitive to ambient temperature changes, with heat exposure leading to temporary reductions in fertility. Handling, training, and housing conditions can influence a boar’s willingness and ability to mate (Sabei et al., 2023). It is important to identify key reproductive challenges and evaluate strategies for addressing them.

4 Reproductive challenges and current strategies

Multiple obstacles remain in the way of ideal boar fertility and reproductive efficiency, even with advancements in animal breeding and reproduction (Peltoniemi et al., 2019). These challenges include management inefficiencies, nutritional deficits, environmental stressors, and physiological restrictions. Subfertility is often caused by aberrant spermatogenesis, poor semen quality, and testicular degeneration (Flowers, 2022). Libido and spermatozoa morphology can be jeopardised by inbreeding (Auler et al., 2017; Abah et al., 2023).

Heat stress is a huge threat to boar welfare, reproduction, and productivity under the current global warming scenario. Increased aberrant forms, changes in membrane integrity, and decreased spermatozoa motility are all results of disrupted spermatogenesis caused by high temperatures (Yadav et al., 2022). Deficits in zinc, selenium, and vitamin E cause nutritional imbalances that weaken antioxidant defences and raise oxidative stress in spermatozoa (Kowalczyk, 2022). In addition, reproductive tract infections compromise semen quality and libido and also pose a threat (Lopez-Rodriguez et al., 2017). These challenges are made worse by inadequate biosecurity and improper management of semen during AI (Górski et al., 2017). Furthermore, early detection and management of fertility are hampered in underdeveloped regions by a lack of sophisticated reproductive monitoring equipment. To guarantee sustainable boar fertility and productivity, an integrated strategy incorporating genetic enhancement, environmental management, healthcare, and reproductive monitoring is needed.

To increase the efficiency of pig production, farmers are compelled to reduce reproductive difficulties. Strategies such as environmental management, genetic selection, dietary optimisation, and assisted reproductive technologies (ARTs) have been put into practice (Lopez-Rodriguez et al., 2017; Waberski et al., 2019). There are, however, barriers to applying these strategies, especially in production systems with limited resources. Selective breeding for reproductive traits, combined with genomic selection and marker-assisted breeding, has enhanced spermatozoa quantity and quality in elite boar lines while identifying fertility-related genes such as oestrogen receptor (ESR), prolactin receptor (PRLR), and FSH receptor (Llavanera, 2024). Furthermore, advances in semen cryopreservation, artificial intelligence, and in vitro fertilisation have increased the effectiveness of genetic propagation (Kumar and Dwivedi, 2025). However, spermatozoa cryopreservation in boars remains problematic due to the susceptibility of spermatozoa membranes to cold shock and oxidative damage.

Nutritional strategies emphasise antioxidant remedies and trace minerals to counteract OS and improve spermatozoa viability (Netshirovha et al., 2026; Ferramosca and Zara, 2022). The routine screening of spermatozoa is another strategy, and digital devices have increased fertility assessment accuracy (Tanga et al., 2021). Improving boar reproductive performance is limited by biological, financial, and technical constraints. The integration of cutting-edge genetic tools, affordable reproductive technologies, and sustainable management techniques adapted to regional production conditions is essential for future advancement. Representation of boar fertility issues, existing intervention options, and the potential relevance of medicinal plants is shown in Figure 2. Therefore, as reproductive challenges continue despite existing improvement efforts, focus has shifted to alternative, nature-based approaches. There is, therefore, a compelling argument for investing in medicinal herbs to improve boar reproductive efficiency.

5 Medicinal plants with potential to enhance boar reproduction

Using medicinal plants to cure illnesses and dysfunctions dates back thousands of years, and, as plants are the source of approximately 25% of contemporary medications, they have significantly aided the development of medicines (Chaachouay and Zidane, 2024). There has been huge interest in evaluating natural materials as a source of potential medications for the past 20 years (Newman and Cragg, 2016). Phytotherapy is gaining interest due to the limitations of conventional medicine, the adverse effects of industrial medications, and the proven benefits of plant-based treatments (Esteves et al., 2020). Phytomedicines provide reviving and nutritional benefits for the body (Valavanidis, 2016). Natural products are becoming increasingly essential for their efficacy. One of the promising natural remedies currently attracting both global and national interest is derived from hempseed, which has an influence on rural economic development, market growth expansion, and new cash crops for farmers.

5.1 Effect of hempseed (Cannabis sativa L.) supplementation on boars

Understanding the chemical and physicochemical makeup of hemp is important for understanding its influence on pig performance. Evaluating the nutritional and functional traits of hemp is essential to mitigate feed shortages in the pig feeding initiative (Table 1). The physical and environmental conditions in which hemp is cultivated and the method applied to extract starch influence the quality of hemp. Hempseed, hemp meal, and hemp leaf meal are popular varieties of hemp that are rich in carbohydrates, a macronutrient that supplies energy and supports essential physiological processes (Axentii and Codină, 2024). Between 20 and 30% of hemp seeds are composed of carbohydrates, and 98% of the carbohydrates are dietary fibre, mostly insoluble fibre. Hempseed contains starch instead of other carbohydrates and are regarded as a nutritious dietary source with adequate fibre. Cellulose makes up 46% of the insoluble fibre, followed by lignin (31%), and then hemicellulose (22%) (Montero et al., 2023).

Table 1. Nutritional composition of hempseed.

Hempseed processing can increase protein concentration, producing defatted meal (~44% protein), protein concentrates (50%–75%) for food formulations, and hemp protein isolates (HPI) with over 85% protein (Montero et al., 2023). Aluko (2017) demonstrated that this final fraction can improve chronic pathology-related illnesses, such as hypertension and polycystic kidney disease. The majority of proteins are in the seed’s inner layer; there are very few proteins in the hull. Furthermore, although rare allergic reactions may occur, hempseed protein is less likely than other seed proteins to induce allergies (Mamone et al., 2019). The two main proteins found in hemp seeds are edestin (67%–75%), a legumin protein, and albumin (25%–37%), which are storage proteins. With a larger quantity of sulphur-containing amino acids (methionine and cysteine), aromatic, branched-chain, and hydrophobic amino acids, edestin is nutritionally superior to albumin, despite the latter being regarded as a high-quality protein (Malomo and Aluko, 2015). In addition to providing several amino acids, hemp seeds have protective and anti-inflammatory benefits and regulate the function of organs and metabolism (Aluko, 2017). β-conglycinin is another small protein (up to 5%). The amino acid profile exhibits elevated levels of arginine, small amounts of sulphur-containing amino acids, and a paucity of lysine (Castro and Kim, 2020). The antioxidant capabilities of hemp protein isolate (HPI) may be due to peptides with amino acid fragments linked to bioactive sequences, such as bioactive peptides (Mamone et al., 2019). Thus, the digestibility of the concentrated proteins is improved by the removal of the hull fraction (Castro and Kim, 2020).

There is currently no research particularly assessing hempseed’s impact on boar reproductive performance, despite its nutritional and bioactive potential. There are few or no controlled trials assessing the influence of hempseed supplementation on boar semen quality, spermatozoa fatty acid composition, oxidative indicators, libido, and fertility. Most studies focus on sows, growing pigs, or meat quality rather than male or boar reproductive parameters. According to Zhang (2024), feed intake and crude protein digestibility were not adversely affected by hempseed meal added to the diets of developing barrows. Pigs tolerate diets containing up to 15% Hempseed meal (HSM). Hempseed hulls have also been fed to pigs as a supplement to treat gastric ulcers; this is thought to work by inflating the stomach contents (Madsen et al., 2022). In comparison to sows fed diets formulated with 5% soybean meal (SBM), the addition of HSM up to 5% to the diets of nursing sows increased the nutritional profile of milk, with greater n-3 fatty acid concentration and greater litter Average Daily Gain (ADG) (Lanzoni et al., 2024). Although these findings demonstrate that hemp-derived products might be nutritionally safe and even helpful, there is still little direct data about how they affect boar reproductive performance, highlighting the need for further species-specific studies.

The nutritional and practical relevance of hempseed in animal production systems is mostly dependent on their lipid content and fatty acid composition. Over 90% of all fatty acids in hempseed oil are unsaturated, and the ratio of omega-6 to omega-3 (ω-6/ω-3) is favourable (Crescente et al., 2018). Linoleic acid (LA; 55%–64%), α-linolenic acid (ALA; 15%–26%), and oleic acid (OA; 9%–23%) are the main fatty acids (Taaifi et al., 2021). Fatty acids are vital for the structure, fluidity, and function of spermatozoa membranes, which are necessary for motility, viability, and fertilisation potential in boar reproduction (Yuan et al., 2023). Sperm membrane integrity and tolerance to oxidative stress are known to be impacted by polyunsaturated fatty acids, especially ω-3 fatty acids (Abdollahzadeh et al., 2023). However, there is currently little direct research assessing the impact of fatty acids obtained from hempseed on the fertility and quality of pig semen. Considering dietary fatty acids have been proven to affect sperm quality and reproductive performance in other animal models, some functional interpretations are based on general physiological knowledge. However, as species-specific variations in lipid metabolism and reproductive physiology may affect the response in boars, such generalisations should be considered cautiously. Therefore, more investigation is needed to determine how hempseed lipid supplementation directly affects pig reproductive characteristics.

Fatty acids, mainly polyunsaturated fatty acids (PUFAs) such as omega-3 (n-3) and omega-6 (n-6), are essential for pig reproduction (Soydan et al., 2020). There has been interest in the potential of adding fatty acids to the diet to improve the quality of semen and the general reproductive performance of boars (Yuan et al., 2023). Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are examples of omega-3 fatty acids that decrease inflammation and improve cell membrane fluidity (Mariamenatu and Abdu, 2021). Omega-3 fatty acids’ increased membrane fluidity may improve spermatozoa penetration of the egg and hasten fertilisation (Yuan et al., 2023). Docosahexaenoic acid improves spermatozoa motility, viability, and morphology by maintaining the stability of spermatozoa membrane integrity (Abd-Elaziz et al., 2024). Omega-3 fatty acids have a positive impact on the hormonal control of spermatozoa production. They may help maintain testicular vitality and increase spermatozoa production owing to their potent anti-inflammatory qualities. Moderate consumption of omega-6 fatty acids has been associated with increased spermatozoa motility and viability (Odetayo et al., 2024). Increased consumption of fatty acids may result in OS, which would lower semen quality (Ochyra et al., 2022). Genotype has a significant impact on fatty acid composition; OA and ALA are the most impacted, but LA shows less variation as a result of genotypic alterations (Irakli et al., 2019). Roasting hemp seeds alters the product’s structure, chemistry, organoleptic characteristics, and physical properties (Babiker et al., 2021).

Phenolic acids, flavonoids, and phytosterols are some of the many bioactive compounds in hempseed that promote its antioxidant, antibacterial, and anti-inflammatory qualities, in addition to its nutritional benefits (Axentii and Codină, 2024). Hempseed’s antioxidative properties, which include reducing cellular damage and neutralising free radicals, are mostly attributed to its phenolic content. Hempseed oil strengthens the product’s standing as a functional food (Apetroaei et al., 2024). The seeds are used more frequently in the food, pharmaceutical, and nutraceutical industries since they are easily processed into a variety of products, including meal, oil, protein powder, and beverages. The commercialisation of hempseed still faces obstacles despite its many benefits, such as legal barriers, low consumer knowledge, and false beliefs about its connection to cannabis (Brownlee, 2020). The form of vitamins found in seeds is determined by their high fat content. Tocopherols, known as vitamin E, and vitamin A are therefore fat-soluble vitamins that are present in hemp seeds. Hempseed oil contains 562–930 mg/kg and 78 mg/kg of vitamins E and A, respectively (Oseyko et al., 2019). Tocopherol isomers such as α-, β-, γ-, and δ- are found in hemp seeds. γ-tocopherol is the most prevalent type, followed by α-, δ-, and β-tocopherol. Hempseed oil’s oxidative stability depends on γ-tocopherol, a potent antioxidant. The content of α-tocopherol, the most vitamin-active isomer, varies depending on the section of the seed. However, when measuring α-tocopherol in seed oil, its concentration can rise to between 0.7% and 25%, influenced by the plant’s genotype and environmental factors (Leonard et al., 2019). Hemp-based diets may be used without negatively affecting growth, product quality, or reproductive factors, according to data from livestock species. Nevertheless, controlled research assessing the direct effects of hempseed supplementation on boar reproductive function is significantly lacking, despite the well-established roles of fatty acids, antioxidants, and amino acids in male reproductive physiology. This information gap highlights the need for targeted research to determine appropriate hempseed inclusion levels, physiological responses, and potential reproductive benefits in boar breeding.

5.2 Effect of Allium sativum supplementation in boars

Garlic is a natural supplement that shows potential for pig nutrition as interest in phytogenic feed additions develops, due to its antibacterial, antioxidant, immunomodulatory, and reproductive health advantages (Abd El-Ghany, 2024). Allicin, diallyl disulphide, S-allyl cysteine, and other trace minerals, including zinc and selenium, are among the bioactive substances present in garlic that have shown notable biological activity in animals (Kalykova et al., 2022). Garlic increases spermatozoa count, seminal vesicles, and epididymis weight through its antioxidant properties (Omotoso et al., 2010). As early as 3000 BC, garlic was used to cure conditions of the uterus, heart, lungs, skin, diarrhoea, headaches, wounds, tumours, and arthritis (Zafar et al., 2023). The perennial plant can grow 100–300 cm tall and produces green or pink flowers (Mansouri et al., 2017). It is used extensively as a medicinal herb and food flavouring, and it is one of the herbs that has a long history of medical use (Deng et al., 2023). The dosage and administration methods have a major impact on the effectiveness of Allium sativum. Garlic’s constituents vary in their metabolism and activity based on the form and processing method. In pig diets, the ideal inclusion levels typically fall between 0.5 and 2% of dry matter; however, overly high dosages may make the feed less palatable or cause digestive tract irritation (Chen et al., 2021).

Different garlic products, such as fresh garlic, garlic powder, aged garlic extract, black garlic, garlic oil, and garlic protein, exhibit distinct nutritional profiles, each contributing to animal health and reproductive performance, as shown in Table 2. Fresh garlic bulbs contain approximately 6%–9% protein, with protein digestibility of 60%–70% (Khokhar, 2022). Garlic powder has a higher protein content of approximately 17%–20%, but moderate digestibility due to protein denaturation during processing. Aged garlic extract (prolonged fermentation) contains lower protein levels of approximately 1%–2%, and is rich in stable antioxidant peptides, which include s-allyl cysteine (Yudhistira et al., 2022). The antioxidant capacity of this extract demonstrates promising supplement qualities for improving spermatozoa quality, DNA protection properties, and damaged spermatozoa cells (Kowalczyk, 2022).

Table 2. Nutritional quality of different types of garlic.

PC, protein content; PD, protein digestibility; and CC, carbohydrate content.

Garlic contains various bioactive chemicals that contribute to its medicinal qualities, the most prominent of which is allicin (dialkyl thiosulfinate). Garlic has been widely shown to have antimicrobial, antihypertensive, anticholesterolemic, and hepatoprotective characteristics. It may also contribute to improved glucose management by interacting with insulin receptors (Roozbeh et al., 2016). These bioactive substances, especially those that include sulphur, have strong antioxidant effects that aid in scavenging reactive oxygen species and shielding tissues from oxidative damage (El-Saadony et al., 2024). Oxidative damage is one of the primary factors affecting male fertility, as it damages spermatozoa and impairs hormone production. Antioxidants from garlic may promote reproductive function since oxidative stress damages spermatozoa and interferes with hormone production, which is a primary factor impairing male fertility. Nevertheless, since species variations in reproductive physiology and metabolism may affect responses to nutritional supplementation, extending these results to boars should be done with caution. Although there is not much concrete evidence regarding boars, there may be advantages for reproduction. Jun-Cheol et al. (2010) reported that adding 3% whole garlic powder (WGP) to a boar’s diet increased libido and semen productivity, including the frequency of ejaculations and the total quantity of spermatozoa per ejaculate. These results indicate that supplementing boars with garlic may improve their reproductive success, but more controlled research is needed to validate its benefits on fertility parameters and spermatozoa quality. Although the majority of the research focuses on other animal models, such as rats, bucks, or rabbits, evidence indicates that similar mechanisms are at work in boars, indicating the possible use of garlic supplementation in breeding programmes. The antioxidant effects of garlic, particularly in powder or extract form, on improving semen qualities and reproductive success have been the subject of various investigations, as shown in Table 3. The pig genetic industry depends on the cryo-banking of boar spermatozoa, although cryopreservation has been demonstrated to harm some structural and ultrastructural sperm components (Sehlabela et al., 2023). However, Iruo (2025) found that extended boar semen at a concentration of 100 µg/mL had the most reliable antioxidative impact on spermatozoa liveability, maintained membrane integrity, and decreased lipid peroxidation. Additionally, when a 125 µg/L concentration was added, Sokunbi et al. (2020) showed improved cryoprotection to the spermatozoa compared to the control.

Table 3. Effect of Allium sativum on boar semen quality.

There are still limited studies that particularly assess the effects of garlic (Allium sativum) supplementation on boars, even though it has been extensively studied in swine nutrition. Since garlic increases the release of digestive enzymes and improves microbial balance in the gastrointestinal system by suppressing harmful bacteria, it may indirectly benefit boars through improvements in gut health and food utilisation (Abd El-Ghany, 2024). Due to variations in the physiological needs and metabolic activity of mature breeding boars, much of the evidence that is now available in pigs comes from piglets, weaned pigs, or finishing pigs. While adding garlic to finishing pig diets enhanced feed intake and average daily gain, Chen et al. (2021) demonstrated that supplying piglets with 10 mL/100 kg body weight of aged garlic extract significantly improved their gastrointestinal development and body weight gain (BWG) (Ranucci et al., 2015). Pigs’ feed intake, nutritional digestibility, and growth performance have all been demonstrated to be improved by fermented garlic powder (0.2%–0.4%) (Samolińska et al., 2020; Sun and Kim, 2020). Other research has also shown that supplementing young pigs with garlic improves their overall health and lowers the frequency of diarrhoea (Ayrle et al., 2019). Horn (2015) observed that garlic reduced plasma triglyceride and total cholesterol levels, raised piglet growth rate, and decreased the frequency of piglet losses. Furthermore, garlic’s effectiveness in reducing OS goes beyond its advantages for reproduction. While these investigations indicate that garlic may improve nutritional utilisation and general physiological state in pigs, direct proof of these effects in breeding boars is limited. As a result, interpretation of results from earlier stages of production should be done with caution, and more research is needed to understand whether similar improvements exist in boar reproductive performance and semen quality.

Supplementation has been associated with lower levels of lipid peroxidation markers, such as Malondialdehyde (MDA), and higher levels of endogenous antioxidants, such as glutathione peroxidase (GPx) and Superoxide Dismutase (SOD) (Abd El-Ghany, 2024). These antioxidant properties hold significance for sustaining boars’ general physiological health and reproductive health. While there is strong evidence for garlic’s growth performance and as an extender (in vitro), the specific effects of garlic as a direct, long-term dietary feed supplement on boar semen quality are still being studied, with some studies demonstrating positive results and others demonstrating no significant change in concentration. There is, however, a need to determine the effectiveness of Allium sativum as a dietary additive for boars to improve semen quality.

5.3 Effect of Moringa (Moringa oleifera) supplementation in boars

The M. oleifera tree is primarily grown for its numerous applications as a valuable herb due to its nutraceutical and therapeutic qualities (Abd et al., 2020). Moreover, its leaves are frequently utilised because they are rich in various bioactive compounds, including nutrients and phytonutrients (Vergara-Jimenez et al., 2017). These nutrients consist of proteins, vitamins (E, C, beta-carotene, and B-6), minerals (including calcium, phosphorus, and magnesium), and fatty acids (Sun et al., 2020). The inherent bioactive phytonutrients consist of flavonoids, phenolic acids, and glycosides. Additional groups comprise saponins, alkaloids, tannins, isothiocyanates, and glucosinolates (Susanto et al., 2018). The M. oleifera leaves contain phenolic acids, including ferulic acid, gallic acid, vanillic acid, and ellagic acid, with chlorogenic acid being the predominant compound (Manisha et al., 2017).

Moringa supplementation in boars primarily lies in its potential to enhance reproductive performance, immunity, and overall physiological health (Mohlala et al., 2023). Boars require a balanced intake of nutrients to maintain optimal spermatozoa quality, libido, and hormonal function. Moringa supplementation may improve spermatozoa count, viability, motility, and morphology, as shown in Figure 3. Although the use of Moringa oleifera as a dietary supplement for improving boar semen quality is gradually gaining attention, as shown in Table 4, the number of studies specifically conducted in boars remains limited. Ditama et al. (2024) observed that supplementing 1% Moringa oleifera leaf meal in the diet raised the sexual libido of Landrace-cross boars and improved the quality of their sperm, namely, sperm motility and acrosomal membrane integrity. Ketpanyapong and Marupanthorn (2023) found a positive link between 50 mg/kg Moringa Oleifera Leaf Extract (MOLE) supplementation and better semen quality in boars. However, Laskar et al. (2025) discovered that 300 µg/mL Moringa oleifera leaf extract was more effective than other concentrations for preserving boar spermatozoa at 18 °C. Furthermore, Setyawati et al. (2024) concluded that using 1% Moringa oleifera leaf meal in feed improved sperm quality over time, particularly when fresh or at the start of storage. In addition, the high zinc concentrations in Moringa leaves increase testosterone production by the Leydig cells in the testes (Widhyari et al., 2015). The addition of Moringa leaf flour to the meal was found to increase its nutritional value and enable more optimal spermatozoa metabolism (Mohlala et al., 2023). Spermatozoa had a greater chance of surviving and performing well during the reproductive process, as evidenced by an increase in spermatozoa viability from 58% to 67% (Dcunha et al., 2022).

Table 4. Effect of moringa (Moringa oleifera) on boar semen quality.

The inclusion of Moringa leaf meal in the diet enhanced the quantity and quality of semen in Landrace cross boars, as evidenced by the increase in spermatozoa motility and viability (Mohlala et al., 2023). Mohlala et al. (2023) reported that the protein and mineral zinc in Moringa leaves promote the generation of testosterone by Leydig cells in the testes and help spermatozoa mature during the spermatogenesis process. Improved spermatozoa motility can boost the likelihood of fertilisation of the egg, enhancing female animals’ chances of successful reproduction (Waberski et al., 2022).

Moringa helps mitigate OS due to its high antioxidant capacity in reproductive tissues, a common factor that impairs spermatozoa quality in male animals. Although research on boars is still limited, the physiological similarities support extrapolation of these findings to pig reproduction. Boar wellbeing is enhanced by the bioactive components found in Moringa, such as flavonoids and phenolic acids, which enhance disease resistance, modulate the immune system, and boost general physiological wellbeing beyond reproductive functions (Ali and Khatun, 2025). Moreover, Moringa modulates lipid metabolism and reduces serum cholesterol and glucose levels, thereby improving metabolic issues and lowering the chances of reproductive decline brought on by obesity (Mohamed et al., 2019). Antibacterial and anti-inflammatory properties may help reduce the need for antibiotics in boar management as pig farming advances towards antibiotic-free methods. According to Mahfuz and Piao (2019), Moringa can be added to swine diets in several ways, including pelleted feeds, dried leaf powder, and aqueous extracts. Higher levels may decrease feed palatability and impair nutrient absorption due to the presence of tannins and saponins, but lower inclusion rates (up to 5%) are often linked to improved performance and few anti-nutritional consequences (Samtiya et al., 2020). As a result, finding the optimal dosage is key for maximising benefits while avoiding potential disadvantages. There is enough evidence to conclude that feeding a certain percentage of Moringa oleifera leaf meal to boars significantly improves their libido and semen quality (Ali and Khatun, 2025). However, the available data demonstrate that Moringa is an efficient, natural, and cost-effective replacement for boosting pig reproductive performance, even though research in ruminants is more numerous.

5.4 Effect of oregano (Origanum vulgare) supplementation on boars

The rich phytochemical profile of oregano (Origanum vulgare) makes it a popular and therapeutic herb (Sharifi-Rad et al., 2020). In addition to having a potent aroma, the herb contains high concentrations of physiologically active compounds, such as carvacrol and thymol (Grigore-Gurgu et al., 2025). Oregano supplementation has been investigated in pig production to improve overall health and productivity, and to address boar management issues, including immunity, reproductive efficiency, and boar taint (Hofmann, 2021). Phenolic chemicals, such as thymol and carvacrol, are frequently found in the plant’s essential oil and regulate numerous biological processes (Mączka et al., 2023). Apart from these primary components, oregano also contains vitamins, minerals, such as calcium, potassium, and magnesium, terpenes, rosmarinic acid, and flavonoids (Skrypnik et al., 2024). Given that they help combat free radicals and reduce OS, these phenolics are primarily responsible for oregano’s antioxidant qualities (Azimzadeh et al., 2024). The antibacterial properties of oregano are also important, especially in animal production practices that aim to reduce the use of antibiotics (Elfadadny et al., 2024). In boar nutrition, oregano is primarily applied for its functional benefits rather than as a traditional nutrient source. It is commonly administered as essential oil, dried powder, and phytogenic feed additives, either alone or in combination with other herbs (Kholif and Olafadehan, 2021). Oregano’s ability to improve immunological function, lessen boar taint, and improve reproductive performance is what drives its use in boars (Hofmann, 2021). These effects are linked to oregano’s antioxidant capacity, which protects spermatozoa from oxidative damage, in addition to its possible modulation of endocrine functions related to testosterone production (Al-Najar et al., 2022).

Liu et al. (2017) offered evidence supporting the idea that oregano essential oil improves boar antioxidant capacity, particularly in relation to spermatozoa generation and motility characteristics. However, Cheng et al. (2018) demonstrated that pigs fed oregano essential oil (EO) had better growth performance, likely due to improved intestinal morphology and balanced gut microbiota. While growth is not the primary focus, improved nutrition utilisation may indirectly support the reproductive and physical health of developed boars. Oregano’s effect on boar reproductive parameters appears beneficial. According to El-Sayed et al. (2024), oregano EO supplementation significantly increased semen volume, spermatozoa motility, and spermatozoa viability in boars under heat stress. In a similar way, Alberto (2020) found that boars had higher testosterone levels and better libido while receiving herbal additives that included oregano. These advantages are viewed as being derived from oregano’s antioxidant qualities, which may help regulate the hormonal system and protect reproductive cells from OS.

Hofmann (2021) demonstrated that dietary oregano supplementation reduced skatole levels in boars, potentially by modifying gut microbial populations responsible for producing skatole precursors. Moreover, oregano may influence liver enzyme activity involved in the metabolism of taint compounds, thereby contributing to improved meat quality in intact males (Huang et al., 2025). Additionally, taking supplements of oregano has been linked to higher activity of antioxidant enzymes, such as catalase (CAT) and SOD, and lower levels of OS markers, such as MDA (Shirvani et al., 2023). These improvements in immune defence may reduce the incidence of infections and enhance the overall wellbeing of boars. Despite these encouraging findings, limitations remain. Most studies have been conducted on pigs in general, with relatively few targeting boars specifically. Variations in oregano forms and dosages hinder comparisons, highlighting the need for long-term studies on its effects on boar reproduction.

6 Future prospects and research gaps

Researchers are increasingly focusing on natural, plant-derived products as sustainable alternatives to synthetic reproductive enhancers, antibiotics, and chemical-based feed additives as concerns about their use grow (Reski et al., 2026; Fatima et al., 2024; Jin et al., 2023). Despite an increasing number of early discoveries and growing interest in the reproductive benefits of plant-based treatments, the systematic use of medicinal plants in boar fertility management remains rare and underdeveloped. Major contributing factors include differences in plant composition, inconsistent dosing schedules, a lack of standardisation in extraction methods, and limited understanding of the molecular mechanisms underlying their reproductive effects. It is often challenging to convert experimental results into practical, farm-level applications due to the methodological inconsistency of current pig reproduction research. Considering the amount of research on basic semen quality assessments or preliminary antioxidant evaluations, there are major information gaps in dosage optimisation, toxicity profiles, long-term reproductive safety, and interactions between plant chemicals and physiological systems in boars. In order to establish medicinal herbs as reliable, scientifically grounded ways to increase boar reproductive efficiency, it is critical to close these gaps. In addition to explaining the mechanisms by which plant extracts exert their reproductive effects, successful research programmes that integrate phytochemical characterisation, controlled animal trials, spermatozoa extender development, and toxicological evaluation will enable the development of standardised, repeatable preparations appropriate for practical use.

A comprehensive, multidisciplinary strategy that incorporates field-level assessment, controlled animal testing, and phytochemical characterisation should be used in future research projects. These disciplines include animal science for designing and conducting controlled boar trials, phytochemistry, biostatistics, reproductive physiology, and veterinary science. Screening of phytochemistry and bioactive compounds will help identify and measure phenolics and flavonoids, and evaluate endocrine-modulating, antioxidant, and antipathogenic properties. Chemical fingerprints, potential markers for quality control, and prioritised extracts for in vivo testing will be obtained as a result. Controlled dose-response (biostatistics) and mechanism studies in boar semen and fertility programmes would help determine optimal doses for improving semen volume, concentration, motility, and OS. This type of research programme will result in dose recommendations, mechanistic data, and evidence for semen preservation additives. Programmes for developing and testing semen extenders (reproductive physiology) with standardised plant antioxidants at predetermined concentrations for cryopreservation and short-term storage serve a vital role. This tool can also compare control and spermatozoa motility treatments and extenders, and include storage time and freeze-thaw trials, to produce extender formulations that are ready for testing. Acute and sub-chronic toxicity (veterinary science), together with reproductive toxicity screenings, should be performed as part of safety, toxicology, residue, and regulatory pathway programmes. Through this technique, safety dossier outputs for feed additive registration, label restrictions, and warnings will be developed.

In the future, the application of medicinal plants in pig production should be explained in a way that demonstrates both their biological effectiveness and their efficacy in actual production systems. These environments include intensive and extensive systems. When examining intensive systems, most research on medicinal plants in pig production still uses feed-based meals. Furthermore, the use of extracts through water systems has not received much attention, especially regarding microencapsulation. This method has not yet received significant attention in boar reproductive studies, despite its huge potential to enhance semen quality and provide better controlled dosing. Encapsulating plant bioactive compounds in protective microcapsules significantly improves the stability, absorption, and bioavailability of antioxidants and phytochemicals, ensuring that more of the active components reach the reproductive system. Water administration of these microencapsulated supplements offers a practical, low-stress approach suitable for agricultural settings, allowing continuous ingestion without requiring specific equipment or altering feeding habits. Since it functions in communal pens, there is no necessity for changing feed suppliers, there is no threat of feed contamination, and it is easy to turn on and off during the trial period; this approach would be appropriate for both commercial and experimental farm setups. Although this method has been well researched in other livestock industries, it is a practical and intriguing way to investigate improvements in spermatozoa motility, viability, membrane integrity, and OS markers. As a result, microencapsulated water-based supplementation is a unique, useful, and environmentally friendly strategy that can fill in existing study gaps and advance our understanding of how plant-derived compounds impact pig semen quality.

In large-scale systems, research may examine the creation of spaces where farmers can cultivate forage rows, forage plots, or small herbal gardens with plants that promote defence mechanisms and reproductive success. Then, while grazing, pigs can consume the plants. Additionally, farmers can dry the leaves to make leaf meals, mix them with ordinary feed, or manufacture plant-based mineral licks that pigs are free to eat. These methods are especially appropriate for outdoor production since they make use of the environment and the pigs’ natural behaviour. It is clear from discussing these simple, useful techniques that medicinal plants may be successfully used in both intensive and extensive settings, making them a suitable option for improving pig production.

Allium sativum, hempseed, oregano (Origanum vulgare), and Moringa oleifera are recommended as beneficial supplements to the diets of breeding boars, as shown in Table 5. These recommendations are based on straightforward, low-cost application methods that agricultural extension officers and farmers can easily use to increase reproductive efficiency in a sustainable manner. Fresh Moringa and oregano leaves can be collected, finely chopped, and added directly to animal feed (Shea, 2024; Armah, 2024). To assess feed intake, body condition, and overall animal response, farmers can start by feeding small amounts and repeat the process two or three times a week. Farmers will be able to assess acceptance using this method before increasing or maintaining inclusion levels. An effective substitute and widely used method is sun-dried leaf powder. To maintain their therapeutic qualities, Moringa and oregano leaves can be harvested, dried in the shade, ground into a fine powder, and stored in airtight containers (Shirish, 2021; Hazarika, 2024). To support consistent consumption, the powder can be introduced to boar diets at small intake levels, particularly in the early stages. Another easy method is water-based supplementation, which involves combining small amounts of dried leaf powder with drinking water (Khan et al., 2025). This strategy may be effective in situations when feed mixing is limited, but careful monitoring is essential to ensure normal water intake.

Table 5. Effects of hempseed (Cannabis sativa L.), Allium sativum, Moringa oleifera, and Origanum vulgare on the reproductive parameters of boars.

• indicates no data found on boar reproductive performance.

Allium sativum can be prepared efficiently by peeling, thinly slicing, sun-drying, crushing, and grinding the cloves into a powder before storing them in sealed containers (Uttam, 2024). Garlic powder can be added to boar feed in small amounts at first to avoid feed rejection. Instead of giving freshly crushed Allium sativum every day, it can be added to moist feed and administered two or three times a week (Cheang-Deis, 2023). It is crucial to emphasise to farmers that garlic should be consumed as a nutritional supplement rather than in place of a wholesome meal. Although little is currently known about the use of hempseed in boar reproduction, observations regarding its nutritional value and antioxidant properties in other animal husbandry systems suggest potential advantages. Farmers are advised to follow local regulations when cultivating and using approved industrial hemp varieties. At present, hempseed should be considered a promising but experimental feed supplement for breeding boars, requiring further scientific research and regulated on-farm testing.

In conclusion, the antioxidant, anti-inflammatory, and antibacterial qualities of medicinal plants, including Moringa oleifera, Allium sativum, Origanum vulgare, and hempseed (Cannabis sativa L.), may significantly enhance boar reproductive efficiency. Addressing gaps in dosage maximising, toxicity evaluation, and delivery strategies, particularly less prevalent ones, such as microencapsulated water-based supplementation, will be necessary to translate experimental results into practical agricultural applications.

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Footnotes

Edited by: John Michael Gonzalez, University of Georgia, United States

Reviewed by: Toncho Penev, Trakia University, Bulgaria

Filipa Cristina Costa Ferreira, Instituto Nacional de Investigacao Agraria e Veterinaria Polo de Santarem, Portugal

Adewale Ayodeji Adeyeye, Usmanu Danfodiyo University, Nigeria