Sun Yat-sen University Study: Rosemary Triterpenic Acids Keep Whiteleg Shrimp Survival at About 90% After 24 Hours of Acute Hypoxia
Rui Feng, Xiaomin Li and colleagues at Sun Yat-sen University published a study in Aquaculture feeding whiteleg shrimp a rosemary extract containing 41.15% triterpenic acids for 56 days; the 0.045% supplementation group showed about 90% survival after 24 hours of acute hypoxia, versus only about 40% in the control group.
A study by Rui Feng, Xiaomin Li and colleagues at Sun Yat-sen University shows that triterpenic acids derived from rosemary (Rosmarinus officinalis), used as a feed additive, can support the growth of whiteleg shrimp (Litopenaeus vannamei) and improve their tolerance to hypoxic conditions. The study was published online on July 29, 2026, in Aquaculture, Volume 626, article number 744425.
The raw material used in the study contained 41.15% triterpenic acids, with the main components being ursolic acid, oleanolic acid and betulinic acid. The trial used 540 shrimp postlarvae with an initial body weight of about 0.69 g each, assigned to six dietary treatment groups with triterpenic acid supplementation levels of 0, 0.015%, 0.03%, 0.045%, 0.06% and 0.075%, and reared for 56 days. After the rearing period, the shrimp underwent a 24-hour acute hypoxia stress test to assess their tolerance.
Growth results showed that the 0.045% supplementation group had the best overall growth performance: final body weight, weight gain, specific growth rate and feed intake were all higher than in the control group, while feed conversion ratio was lower. Regression analysis based on weight gain determined an optimal supplementation level of about 0.0416%.
The growth improvement was accompanied by marked changes in hepatopancreas and intestinal structure. Within the 0.015% to 0.06% supplementation range, hepatopancreatic tubules were more intact and the numbers of B cells, R cells and E cells increased, with the best hepatopancreas morphology in the 0.03% to 0.045% groups. Intestinal development was also better, with longer and thicker villi; intestinal wall thickness in the 0.045% group was about 322 μm, compared with about 160 μm in the control group. After hypoxia stress, the control group showed obvious hepatopancreas damage, whereas the hepatopancreas tissue structure in the 0.03% to 0.045% groups remained relatively intact. At the 0.075% supplementation level, the benefits no longer increased, and some adverse signs appeared in the hepatopancreas and intestinal tissues.
The triterpenic acids also supported digestive function. Assessment of digestive enzyme activity before and after hypoxia showed that the supplemented groups maintained or recovered digestive activity better than the control group, while also mitigating the hepatopancreas damage caused by hypoxia stress.
Hypoxia tolerance of the shrimp improved, accompanied by increases in antioxidant gene expression, antioxidant enzyme activity and immune-related gene expression. Before and after stress, the appropriate triterpenic acid supplementation levels increased SOD and GSH-Px activities and total antioxidant capacity, while reducing MDA, an indicator reflecting the degree of lipid peroxidation. The 0.045% group showed the most stable response, with increased expression of antioxidant genes such as nrf2, cat and gpx, and increased expression of nrf2, cat, gpx, myd88, dorsal, relish, hsp70 and hif-1α. After hypoxia stress, expression of hif-1α, a key hypoxia-response gene, was also increased in the 0.045% group.
These physiological changes were directly reflected in survival rates: after 24 hours of hypoxia, only about 40% of shrimp in the control group survived, whereas survival in most triterpenic acid supplementation groups remained at about 90% or higher. Biochemical indicators showed lower stress levels in the supplemented groups; for example, after hypoxia, AST in the control group was about 30.9 U/L, compared with only about 5.6 to 6.3 U/L in the 0.03% and 0.045% groups; plasma glucose fell from 1.73 mmol/L in the control group to about 1.20 to 1.27 mmol/L in these two groups.
Overall, the 0.015% to 0.06% supplementation range produced positive effects, with 0.045% having the most comprehensive effect, and the optimal level estimated based on weight gain being 0.0416%. The effects showed dose-dependent characteristics: 0.075% brought no additional benefits and instead increased ALT after hypoxia and showed signs of damage in the hepatopancreas and intestine. The study was conducted under experimental conditions, and the authors noted that further evaluation under actual production conditions is still needed.