There are many reasons why fishmeal is recognized as the best source of protein in aquafeeds. These include its high palatability, balanced nutrient profile, easy digestibility, and absorption properties. The current change in global climate, however, that has resulted in a decrease in the catch of capture fisheries, contributing to fishmeal shortages and increased prices (Hodar et al., 2020; Jannathulla et al., 2019). Several studies have been conducted in search of suitable protein sources to replace fishmeal, but a high percentage of fishmeal substitution may negatively affect aquatic animal growth and immunocompetence. As a result of 45% replacement of fishmeal with defatted yellowtail worm, Larimichthys crocea exhibits decreased growth performance and immunocompetence (Zhang et al., 2022). It is reported that Oreochromis niloticus and Sarotherodon galilaeus suffer from poorer growth performance and liver health after 20% and 30% replacements with vegetable meal (Sallam et al., 2021). Enhancing the antioxidant and immune capacities of aquatic animals under low-fishmeal diets is considered as one of the ways to reduce the negative impacts of low-fishmeal diets. Therefore, the aquaculture industry needs feed additives that are cost-effective, environmentally safe, and capable of improving shrimp immune capacity.

An herbaceous perennial plant in the Nansingidae family, Ginseng has a long history of medicinal use and is believed to treat a number of ailments, it regulates the immune system particularly well, and is therefore considered an immunomodulator (Kang and Min, 2012). Among its benefits are the enhancement of immunity, improves blood circulation, antioxidant properties, and anticancer properties (Kim, 2018, 2012; Ratan et al., 2021). A wide range of diseases have been treated with ginseng extracts in aquatic animals. It is found that dietary supplementation of ginseng extract significantly improved the survival rate of juvenile Oncorhynchus mykiss (Bulfon et al., 2017). Supplementing Nile tilapia diets with ginseng extract improves growth performance, feed utilization, and hematological indices (Goda, 2008). The survival of fish attacked by Aeromonas hydrophila increases with increasing levels of ginseng in their diets (Abdel-Tawwab, 2015). The addition of ginseng extract to Nile tilapia diets can be used as a natural alternative to hygromycin as a growth promoter and also as an immunoregulator (Elsayed et al., 2014). The main reason for the medicinal value of ginseng is believed to be its main active ingredient, ginsenoside (Guo et al., 2021; Murthy et al., 2014). A number of studies have demonstrated its immunomodulatory and antioxidant properties, along with its anti-inflammatory and anti-stress effects (Elekofehinti, 2015; Güçlü-Ustündağ and Mazza, 2007). Inflammatory responses may be modulated by ginseng saponins, their metabolites or derivatives, including Rb1, Re, Rg1, Rg3, Rg5, Rh2, and Rp1, which modulates inflammatory signaling pathways (Kim et al., 2017; Riaz et al., 2019).

As one of the most common hazardous substances in the aquaculture environment, ammonia nitrogen (NH₃-N) is derived from feed residues, animal excreta, and microbial metabolism (Abdelfatah, 2022; Edwards et al., 2024; Zhang et al., 2023). Ammonia nitrogen is present mostly as free ammonia (NH₃) and as ammonium ions (NH⁴⁺) in water bodies. Free ammonia is less toxic than ammonium ions. Ammonia nitrogen concentrations in the environment cause a wide range of negative effects on aquatic animals, including shrimps (Duan et al., 2024; Lu et al., 2016; Páez-Osuna, 2001). Shrimps will experience physiological stress due to ammonia nitrogen, resulting in an increase in their respiratory rate and blood concentration of ammonia nitrogen, consequently, oxygenation is affected, the acid-base balance and osmotic pressure regulation of the body are affected, and normal metabolism is affected (Valencia-Castañeda et al., 2018). When shrimp are exposed to high concentrations of nitrogen, their growth will be inhibited, resulting in impaired feeding and digestion, slow growth, weight loss, and shortening of their bodies, among other problems (Frías-Espericueta et al., 2000; Lin et al., 1993). Additionally, ammonia nitrogen stress weakens the shrimp’s immune system, making it less resistant to pathogenic microorganisms and susceptible to infection with virus-causing diseases such as white spot syndrome virus (WSSV) (Kathyayani et al., 2019; Ma et al., 2023). Ammonia stress poses a serious threat to shrimp survival and health. To reduce the harm caused by ammonia-nitrogen stress, aquaculture managers need to implement various strategies (Emerenciano et al., 2022). To optimize feed management and minimize the production of feed residues, it is essential to avoid overfeeding. Strengthening water quality management through regular water changes is necessary to maintain adequate dissolved oxygen levels. Additionally, it is critical to reasonably control stocking density to prevent water quality deterioration caused by excessive density. Regular monitoring of key parameters such as ammonia nitrogen concentration, pH, and dissolved oxygen is also imperative, with timely control measures implemented as needed. To protect the health and sustainable development of aquaculture, these methods of scientific management and rational water quality control can effectively reduce ammonia nitrogen stress (Zhang Y. et al., 2020). Current studies indicate that incorporating functional additives into the diet can enhance the stress resistance of aquatic animals under ammonia nitrogen conditions (Jin et al., 2018; Kaleo et al., 2019; Sallam et al., 2020; Yilmaz, 2019).

Ginseng extract has been found to enhance growth and immunity in Nile Tilapia (Oreochromis niloticus) and hybrid grouper (Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀) (Ahmed et al., 2022; Riaz et al., 2019; Sun et al., 2018). Due to its fast growth rate, long breeding season, and tasty meat, L. vannamei has been introduced and cultivated in many countries (Zhang et al., 2019). However, there is still a lack of information on the application of ginseng saponins in the diet of L. vannamei. In this study, we explored the application of ginseng saponins in the diet of L. vannamei and investigated the effects of ginseng saponins on growth performance, antioxidant capacity, and ammonia nitrogen stress resistance of L. vannamei fed with low-fishmeal diet, which provided a theoretical basis for the development of functional feed additives.

As far as growth performance is concerned, L. vannamei in the 0.1% and 0.3% ginseng saponins-supplemented groups outperformed the low-fishmeal negative control. Additionally, the growth performance of L. vannamei in the 0.3% ginseng saponins-supplemented groups was highly similar to that of the high-fishmeal positive control. L. vannamei increased growth performance by adding 0.1% to 0.3% ginseng saponins to low-fishmeal diets, which was close to the PC group. Ginseng saponins may be one of the most important ingredients in shrimp growth. In the similar studies, that triterpenoid, Quillaja saponins has a favorable effect on the growth performance of Cyprinus carpio and Oreochromis niloticus (Francis et al., 2002, 2001). Furthermore, no significant differences in whole shrimp proximate composition were found between the PC group and the low-fishmeal diets supplemented with ginseng saponins.

There are many different kinds of organisms that produce SOD, an enzyme that scavenges superoxide radicals in their cytosol (Chen et al., 2013; Wang et al., 2015). In shrimp hepatopancreas, the MDA content was not significantly different between the 0.3% ginseng saponins-added diet and the 20% fishmeal-added diet, and was significantly lower than the other three treatment groups, and a significantly higher level of enzyme activity was observed in the SOD, T-AOC, and GSH-Px than in the PC group. These results showed that addition of the 0.3% ginseng saponins to a diet low in fishmeal improved the antioxidant capacity of L. vanname. In related studies, ginseng polysaccharide complex has been shown to improve SOD activity in the hepatopancreas of L. vannamei, and to enhance antioxidant activity (Liu et al., 2011). Using the polysaccharide extract from S. fusiforme, Vibrio harveyi was inhibited in shrimp, Fenneropenaeus chinensis, and SOD activity in the shrimp’s muscle increased (Huang et al., 2006). A significant increase in SOD activity and cyt-SOD mRNA expression has been observed in tiger shrimp, Penaeus monodon, after the addition of sodium alginate (Liu et al., 2006). On the other hand, the relative expression of sod, gsh-px, and cat in shrimp of the 0.3% ginseng saponins group was significantly higher than that of shrimp from the PC group in terms of relative expression, that indicated that adding ginseng saponins to low-fishmeal diets could enhance the antioxidant capacity of shrimp from L. vannamei. The study has found that the hepatopancreas mRNA level of sod, cat, and gsh-px can be improved by addition of 0.04% ginseng polysaccharide in diet of L. vannamei (Liu et al., 2011). Furthermore, ginseng saponins added to low fish meal diets improved the morphology of hepatopancreatic tissue of L. vannamei, with 0.3% ginseng saponins being more effective. It was found that under immune stimulation, ginseng saponins increase antioxidant genes expression in the liver of broilers, alleviate liver histology changes, inhibit inflammatory responses, and promote antioxidant activity (Hu et al., 2023). And the protodiol saponin ginsenoside Rk1, isolated from ginseng, has been suggested to have significant antitumor properties (Wu et al., 2024). These studies were consistent with the results of the present experiment. In shrimp, ginseng saponins were found to be beneficial in alleviating the effects of lipid peroxidation damage and improving their antioxidant capacity, especially when 0.3% ginseng saponins were added.

Shrimp is highly susceptible to ammonia stress. Not only does it damage their health, but it may also cause economic losses for aquaculture as well (Chen et al., 2019; Li et al., 2023). Aquatic animals’ survival rate decreased as ammonia concentration and exposure time increased, but different species of aquatic animals tolerated ammonia differently (Frances et al., 2000; Kır et al., 2004; Wang and Walsh, 2000). An increase in the resistance of shrimp to ammonia stress was observed in those treated with immune potentiating agents, such as gracilaria tenuistipitata extract, astaxanthin and mannan oligosaccharide (Fu et al., 2007; Pan et al., 2003; Zhang et al., 2012). In terms of stress resistance, following ammonia-nitrogen stress, shrimp supplemented with 0.3% ginseng saponins survived just as well as shrimp in the high-fishmeal control group, as well as significantly more than shrimp in the low-fishmeal control group. A variety of environmental factors, including pH, nitrites, stress, and temperature, can increase oxidative stress and activate antioxidant genes expression (Guo et al., 2013; Wang et al., 2009; Zhou et al., 2008). In the present study, as with survival rate, the relative expression levels of antioxidant genes sod, cat, and gsh-px were significantly higher in shrimp from the low-fishmeal diet supplemented with 0.3% ginseng saponins than in shrimp from the high-fishmeal diet. A key component of the apoptosis process, caspase3 cleaves a wide range of structural and regulatory proteins through its proteolytic activity (Chang et al., 2009). It is known that oxidative stress activates downstream target genes and induces apoptosis using p53 as a tumor suppressor (Sun et al., 2016). Nitrite exposure has been shown to increase Scylla paramamosain and Pelteobagrus fulvidraco caspase3 and p53 expression in previous studies (Cheng et al., 2020; Zhang M. et al., 2020). Previous study had shown that sensitive to apoptosis genes loss increased pro-apoptotic bax and bcl-2 imbalances in mitochondria. Caspase9 and caspase3 were activated, thereby promoting cell death (Chang and Ding, 2014). As for apoptosis-related genes, shrimp from the 0.3% ginseng saponins supplemented group showed significantly higher expression levels of p53, caspase3, bcl-2, and bax than shrimp from the PC group. As a result of these findings, shrimp stress resistance may be improved by adding 0.3% ginseng saponins to low-fishmeal diets. Ginsenoside Rk1 was found to promote autophagy-dependent apoptosis (Wu et al., 2024). The process of apoptosis is a kind of programmed cell death that is managed by genes. Upregulation of apoptosis may signal that the cells in an organism are still within control. This suggested that shrimp were becoming more stress resistant due to the upregulation of apoptosis genes.

In this experiment, different amounts of ginseng saponins were added to high percentage fishmeal replacement diets of L. vannamei to investigate the effects of ginseng saponins on the nutritional physiology of L. vannamei fed with low fish meal diets. Overall, ginseng saponins, as a natural additive, has a number of positive effects on aquatic animal nutrition, including promoting growth performance, improving antioxidant capacity, and improving anti-stress ability. Ginseng saponins has an extensive application potential in the aquatic feed industry because of its unique characteristics.