RUDN University biologist with colleagues from Germany, Egypt, Iran and Thailand proved that wormwood extract helps to improve the immunity of carp and enhance its growth. The results are published in Aquaculture.
Due to the increasing demand for fish, aquaculture owners are often forced to grow it in "overpopulated" aquaculture systems. High density worsens water quality and causes stress in fish, this reduces immunity and increases the likelihood of the spread of diseases. Fish farmers use antibiotics for treatment, but bacteria can develop resistance to them. In addition, they are unsafe for the environment. A RUDN biologist together with colleagues from Germany, Egypt, Iran and Thailand proved that it is possible to protect fish with a harmless natural preparation - wormwood extract.
"The use of antibiotics in fisheries has numerous environmental and health side effects, including antibiotic-resistant bacteria emergence. The need for sustainable alternatives that increase the system resilience while respecting the environment and especially that do not contribute to the antimicrobial resistance pool, has therefore become an international priority. Despite the rich chemical composition of wormwood and its wide range of properties, the effect of wormwood extract on fish health has not yet been investigated. We have studied how wormwood extract affects common carp – one of the most popular freshwater fish species grown all over the world," said Morteza Yousefi, PhD, Associate Professor of the Department of Veterinary Medicine of RUDN.
Biologists investigated the effect of wormwood extract on the example of common carp (Cyprinus carpio). 300 healthy juveniles were placed in 12 tanks of 70 liters each and for 60 days maintained a diet with a different content of wormwood extract - 0.5%, 1% or 1.5%. Some received the same food, but without wormwood. After that, scientists weighed and measured the fish, took the blood tests and evaluated the feed conversion. This parameter is the amount of feed consumed per unit of weight gained, it shows how effective the feeding was.
The fish that gained the most weight were those that received a 1% wormwood supplement to feed - 134.4%. The fish from the control group, which did not receive plant extract at all, scored the least in percentage terms — only 112%. An increased dose of wormwood (1.5%) did not lead to a significant increase in growth. Fish from this group gained slightly more weight than from the control group - 114.8%. Immunity indicators also turned out to be the best for the group with a one percent addition of wormwood extract. For example, the activity of lysosomes, which are responsible for the digestion of foreign particles, increased by 30% compared to the control group.
"Experimental results allow us to conclude that dietary inclusions of wormwood in juvenile common carp increased growth performance and feed efficiency, improved the innate immunity and antioxidant response, and improved hepatic health. 0.5–1% levels is recommended for common carp diet formulation," said Morteza Yousefi from RUDN University.