The ginkgo tree, also known as the white fruit tree or Gongsun tree, is one of China's ancient tree species and is famously referred to as a "living fossil." In China, the development of ginkgo resources is thriving, with promising prospects ahead. Due to its unique growth patterns and strong disease resistance, the ginkgo has garnered significant attention both domestically and internationally. Research into the effective components and therapeutic benefits of ginkgo has increasingly gained importance, leading to the development of health supplements, cosmetics, pharmaceuticals, and more. Ginkgo's active compounds serve as valuable pharmaceutical raw materials, and their utilization has received considerable attention in many European countries, as well as in Japan and South Korea.
Meanwhile, with advancements in technology and the intensification of livestock farming, the input costs in animal husbandry have continued to rise. To alleviate cost pressures and maximize profits, some feed producers and processing companies have increasingly turned to the widespread use of antibiotics, hormones, and other additives in animal feed. Unfortunately, this practice has resulted in excessive residues of these substances in livestock products. Recognizing the potential risks, the European Union implemented a comprehensive ban as early as 2006 on the use of growth-promoting antibiotics in animal feed.
However, thanks to ongoing technological innovations and improvements in extraction processes, ginkgo leaf extract now holds great promise for application in the feed industry. This article provides a concise overview of the current status and potential applications of ginkgo leaf extract in animal feed.
1. Active ingredients in ginkgo leaf extract
The chemical constituents of ginkgo biloba leaf extract include flavonoids, terpenes, lactones, phenolic acids, as well as compounds such as alkaloids and polyisoprenoids, with their content varying depending on the variety, origin, tree age, and harvesting time. Ginkgo biloba leaf extract has been shown to help lower blood sugar and lipid levels, provide antioxidant effects, and boost immune function[1].
1 .1 Flavonoids
More than 40 flavonoids have been isolated from Ginkgo biloba leaves, among which 20 have had their structures identified. The total flavonoid content ranges from 2.5% to 2.9%, with the majority found in the leaf blades and outer seed coat—these being the primary medicinal parts of the ginkgo tree. The major classes of flavonoids include both monomeric and dimeric types. Monoflavonoids account for 10 specific compounds, including four free forms: kaempferol, quercetin, isorhamnetin, and luteolin. On the other hand, ginkgo's dimeric flavonoids are formed by the polymerization of two flavone aglycones via C-C bonds, comprising several key compounds such as ginkgetin, bilobetin, nor-bilobetin, iso-bilobetin, kaempferide, and 5-methoxy-nor-bilobetin [2].
Ginkgo flavonoids exhibit various beneficial effects, including vasodilation, inhibition of platelet-activating factor, antioxidant activity, and modulation of lipid metabolism. As a result, they are widely used in the treatment of cardiovascular and cerebrovascular diseases, nephrotic syndrome, diabetes, and vascular dementia [3].
1.2 Terpenoid Lactones
Terpene lactones are one of the main active components of Ginkgo biloba leaves, generally referring to the collective term for bilobalide and ginkgolides A, B, and C [4]. A mixed formulation of ginkgolides A, B, and C has already entered Phase III clinical trials for the treatment of asthma, with ongoing evaluations of its efficacy in managing septic shock, cerebral ischemia, kidney transplantation, and burn patients [5].
1.3 Other Ingredients
Including organic acids, polyisoprenoids, polysaccharides, as well as 17 types of amino acids, various trace elements, ginkgol (10-alkyl alcohol), ginkgolone, anacardic acid, laccaic acid, heptadecenoic salicylic acid, stigmasterol, alkaloids, vitamins, chlorophyll, carotenoids, and proanthocyanidins, among others [6].
2 Biological Functions of Ginkgo Biloba Extract
2.1 Enhance the body's immune system
Research on ginkgo leaf extract enhancing immune function has been relatively abundant in human studies, while its application in the livestock industry remains comparatively limited. One study investigated the effects of ginkgo leaf-based bio-feed additives on the growth and immune responses of yellow-feathered broiler chickens, revealing positive impacts on immune-related factors in vital organs such as the spleen, thymus, and bursa of Fabricius [7]. Yang Xiaoyan and colleagues examined how varying proportions of ginkgo leaves influence the immune capabilities of broilers, finding that ginkgo leaves positively promote the development of immune organs in these birds, while also boosting levels of serum total proteins and immunoglobulins like globulins [8]. Meanwhile, Zhao Wenming and his team explored the effects of ginkgo leaf extract on the enzymatic activity and functional capacity of immune cells in mice, demonstrating that the extract significantly enhances lymphocyte dehydrogenase activity, boosts granulocyte myeloperoxidase activity, and improves macrophage phagocytic function [9]. Additionally, Cao Fuliang and his team studied the impact of ginkgo leaf bio-feed additives on the growth and immune responses of yellow-feathered broiler chickens, discovering that broilers fed with these additives exhibited higher relative weights of the thymus, spleen, and bursa of Fabricius compared to the control group—evidence suggesting that ginkgo leaf bio-feed additives effectively support and enhance the immune system of yellow-feathered broilers [7].
2.2 Anti-inflammatory and Antimicrobial
Research by Li Yan and others indicates that ginkgo leaf extract exhibits significant antibacterial effects against common pathogens in livestock and poultry, such as Escherichia coli, Staphylococcus aureus, and Pasteurella multocida. Additionally, the extract has been shown to improve the intestinal microbial flora of broilers while effectively inhibiting the proliferation of harmful bacteria [10].
Furthermore, Shengguo Guo and colleagues conducted antibacterial tests using ginkgo leaf extract against Escherichia coli, Aspergillus niger, Rhodotorula rubra, and Candida albicans, revealing that the extract demonstrates strong inhibitory activity against commonly encountered contaminants, with low effective concentrations and excellent thermal stability. The antibacterial potency is closely related to the concentration of the extract—typically, the minimum inhibitory concentration for most bacterial strains remains below 8%. Moreover, the extract exhibits robust antimicrobial and anti-inflammatory properties [11].
Xiaohua Qu and her team found that increasing the concentration of ginkgo leaf extract significantly enhances its antibacterial activity. They also investigated how varying pH levels and heat treatments influence this activity, concluding that the extract displays its highest antibacterial efficacy under neutral pH conditions (pH 7) [12].
2.3 Regulating Blood Lipids
Many studies have shown that ginkgo biloba extract exhibits significant lipid-regulating effects. Wei Jianming and colleagues, after feeding quails a high-fat diet for two weeks, investigated the impact of ginkgo biloba extract on hyperlipidemia in quails. The results revealed a notable reduction in the number of fat vacuoles, demonstrating that ginkgo biloba extract effectively prevents and treats hyperlipidemia and hepatic steatosis in quails [13]. Meanwhile, Li Dengqing and his team conducted experiments to examine how ginkgo biloba extract influences lipid metabolism and modulates the normal gut microbiota in rats with hyperlipidemia. Their findings indicate that the extract not only regulates microbial community composition but also enhances the beneficial bacteria's ability to absorb and metabolize lipids, thereby inhibiting cholesterol uptake. Moreover, acting as an effector in cholesterol metabolism, the extract facilitates the conversion of cholesterol into fecal sterols—compounds that are not absorbed by the body—thus promoting cholesterol excretion and ultimately helping to maintain healthy lipid levels [14-15].
2.4 Antifree radical
Wang Xuejing and others found through experiments that adding 0.06%–0.12% ginkgo extract can significantly or highly significantly reduce serum triglycerides, increase high-density lipoprotein levels, and lower total serum cholesterol. Additionally, adding 0.24% ginkgo leaf extract markedly decreases malondialdehyde levels in broiler chicken serum, significantly boosts superoxide dismutase activity, and enhances the body's antioxidant capacity [16]. Meanwhile, research by Mou Lingli and colleagues indicates that the primary active components responsible for the in vitro antioxidant effects of ginkgo leaves are flavonoids, while lactones exhibit no notable antioxidant activity [17].
3. Applications of Ginkgo Extract
Zang Sumin and colleagues found through experiments that adding 0.03%–0.12% ginkgo extract to the diet of Ross female broilers had a certain growth-promoting effect. Among these groups, the trial group supplemented with 0.06% ginkgo extract showed the most pronounced growth enhancement. Additionally, the 0.48% ginkgo extract group exhibited a significant reduction in abdominal fat percentage in the broilers, while the 0.24% ginkgo extract group experienced a highly significant decrease in liver fat content—though no growth-promoting effect was observed in this case. Meanwhile, incorporating 0.06%–0.12% ginkgo extract into the broiler feed significantly or extremely significantly lowered serum triglyceride levels, while also showing a trend toward increasing serum HDL levels, reducing low-density lipoprotein cholesterol, and decreasing total cholesterol levels [18-19].
Li Yan, Zhang Li, and other researchers found that ginkgo biloba extract can significantly improve the carcass performance of meat ducks, reduce their blood lipid levels, and regulate lipid metabolism [20-21].
4. Summary
With growing concerns over human drug abuse, pharmaceutical residues, and the escalating issue of bacterial resistance triggered by the misuse of antimicrobial agents, developing novel plant-based alternatives to conventional antibiotics has become one of the hottest topics in the feed additive industry in recent years. Leveraging the unique资源优势 of Ginkgo biloba in China, there is a strong push to vigorously explore the use of Ginkgo extracts as additives in animal husbandry, fully harnessing their remarkable biological properties to address some of the challenges currently plaguing the farming sector. Moreover, the creation of innovative feed flavorings not only supports the industrial-scale development of Ginkgo but also holds tremendous potential for future growth and success.
References
[1] Lin Shuhui. Study on the Effects of Ginkgo Biloba Leaf Extract on Immune Function in Broilers [D]. Fujian: Fujian Agriculture and Forestry University, 2009
[2] Wang Dewei, Zhu Hong, Gao Er. Pharmacological Effects and Clinical Applications of Ginkgo Flavonoids [J]. Food and Pharmaceutical Sciences, 2006, 8(6):7-9
[3] Cao Fuliang, Zhao Lingguo, Wang Guibin, et al. Research on the Preparation and Application Prospects of a Novel Bioconversion-Based Feed Additive from Ginkgo Leaves[J]. Jiangsu Journal of Forestry Science & Technology, 2006, 33(2): 44-47
[4] Han Jinyu, Yan Yingchun, Chang Heying, et al. Extraction and Purification Techniques for Ginkgolide Compounds from Ginkgo Biloba[J]. Chinese Traditional Herbal Drugs, 2002, 33(11): 2-5
[5] Liu Bingguo, Zhang Xinping, Liu Yan. Advances in the Study of Terpene Lactone Compounds in Ginkgo Leaves [J]. Journal of Pharmaceutical Practice, 2011, 29(6):421-425
[6] Zhang Li, Zang Sumin. Research Advances on Ginkgo Biloba Extract in Animal Nutrition[J]. Veterinary Drugs & Feed Additives, 2006, 11(6): 21-23
[7] Cao Fuliang, Chen Guiyin, Wang Guibin, et al. Effects of Ginkgo biloba leaf-based biofeed additive on the growth and immunity of yellow-feathered broiler chickens [J]. Jiangsu Journal of Forestry Science & Technology, 2006, 33(2): 16-17
[8] Yang Xiaoyan, Lin Yuexin, Li Yan. Effects of Ginkgo Biloba Leaf on Growth Performance, Immune Function, and Serum Biochemical Parameters in Broilers [J]. Chinese Journal of Veterinary Medicine, 2007, 43(2): 37-39
[9] Zhao Wenming, Zhang Liping, Shen Haizhong, et al. Effects of Ginkgo biloba Leaf Extract on Enzymatic Activity and Function of Immune Cells in Mice [J]. Shanghai Journal of Immunology, 1997, 17(6): 135
[10] Li Yan, Yang Xiaoyan, Lin Yuexin, et al. Study on the Extraction of Active Compounds from Ginkgo Biloba Leaves and Their Antibacterial Effects [J]. Chinese Journal of Animal Science, 2006, 42(15): 54-56
[11] Guo Jian, Dongyu Huang. Exploration of Ginkgo Biloba Leaf Extraction Techniques and Their Antimicrobial Properties [J]. Grain & Oil Food Science and Technology, 2005, 13(5): 16-18
[12] Qu Xiaohua, Xin Yufeng. Study on the Antimicrobial Effect of Ginkgo Extracts [J]. Heilongjiang Agricultural Science, 2008, (1): 25-26
[13] Wei Jianming. Effects of Ginkgo Biloba Extract on Hyperlipidemia in Quail [J]. Chinese Traditional Patent Medicines, 2003, 19(3): 138-141
[14] Zhang Jiangang, Lü Zongyou, Li Jun. Bioactive Properties of Ginkgo Biloba Extract and Its Application in Animal Feed [J]. China Feed Additives, 2011, 104(2):6-9
[15] Li Dengqing, Zhu Jun, Liang Hui, et al. Effects of Ginkgo Biloba Extract on Lipid Levels and Intestinal Microbiota in Experimental Hyperlipidemia [J]. China Journal of Chinese Medicine and Health Information, 2010, 2(2): 5-6
[16] Wang Xuejing, Zang Sumin, Zhang Li, et al. Effects of Ginkgo Biloba Leaf Extract on Growth Performance, Lipid Profiles, and Antioxidant Function in Broiler Chickens [J]. Animal Husbandry & Veterinary Medicine, 2006, 38(11): 40-42
[17] Mou Lingli, Kou Junping, Zhu Dannie, et al. Chemical Constituents of Ginkgo Biloba Leaves and Their Antioxidant Activities [J]. Chinese Journal of Natural Medicines, 2008, 6(1): 26-29
[18] Zang Sumin, Wang Xuejing. Effects of Ginkgo Biloba Leaf Extract on Growth Performance and Lipid Metabolism in Broiler Chickens [J]. Feed Review, 2006(1): 6–9
[19] Tang Shengqiu, Liang Guitao, Dong Xiaoying. Biological Functions of Ginkgo Biloba Extract and Its Application in Poultry Farming [J]. Journal of Animal Nutrition, 2012, 24(4): 606-611
[20] Li Yan, Zhang Li, Zheng Zhongchao et al. Effects of Ginkgo Biloba Leaf Extract on Early Growth Performance of Meat Ducks [J]. Feed Industry, 2006, 27(5): 25-27
[21] Zhang Li, Li Yan, Zheng Zhongchao, et al. Effects of Ginkgo Biloba Extract (EGB) on Lipid Metabolism in Early Growth Stages of Muscovy Ducks [J]. Feed Industry, 2006, 27(5): 40-43 (Text/Translated by Luo Chunfa from DDC)
