Costa Rica is a producer and exporter of Pacific shrimp (Litopenaeus vannamei), which is grown in brackish water ponds in different parts of the country, mainly in the Nicoya Peninsula.
In many cases, production is semi-extensive and is in the hands of individuals and micro enterprises that lack the resources and infrastructure necessary for adequate technical management.
The contamination of shrimp ponds makes shrimp very susceptible to attack by bacteria and viruses that can cause mortalities of up to 100 per cent. This creates serious problems for farmers as many of them are dependent on bank loans.
Currently, the producers resort to using commercial antibiotics to strengthen the immune system of shrimp and to reduce mortality. However these products are not only expensive, but can also be harmful to the environment.
"The idea of this project was to achieve medium to long term solutions using natural techniques to improve the immune system of shrimp, achieve greater weight gains and feed conversions and thereby increase production and consequently economic gains for producers," said Mr Peña.
The research was supported by companies and institutions such as the Pacific Marine Park, the National Cooperative Salt Producers (CONAPROSAL), the National Veterinary Services Laboratory (LANASEVE) and several research units of the UCR
Alternative to antibiotics
The researcher, who recently graduated as an agronomist, approached the project as part of his final graduation from the School of Animal Husbandry of the UCR.
The idea was to develop an alternative to the excessive use of antibiotics by using natural products which are friendly to the environment to strengthen the immune system of shrimp and are available in the market at an affordable price for the farmers.
The studies used shrimp from farms located in the Nicoya Peninsula. The sample was divided into four groups, three of them had different doses of mannan-oligosaccharides, garlic and a compound of plant extracts added to the feed.
After a period of time, Vibrio parahaemolyticus, one of the most aggressive and damaging bacteria in shrimp farming, was innoculated against.
The analysis determined that mannan-oligosaccharides and garlic effectively worked against conventional bacteria, reduced mortality and contributed to higher growth rates.
The plant compound was less effective. However, in all three cases the results were superior to those of the control sample of a basic feed.
"It must be that the effect of shrimp cytotoxins produced by bacteria perish, but in many cases did not occur when using garlic or mannan-oligosaccharides. Both performed well, but the garlic was much better," said Mr Peña.
The study proved that the use of these natural products in shrimp can significantly increase their weight and achieve a better immune response, which also favours a higher income of farmers.
In fact the results are so startling that some farmers in the area of the Gulf of Nicoya are now producing organic shrimp for the international market, using the natural products recommended by Mr Peña.
This is the first study of its kind conducted in the country and although the results are important, Mr Peña acknowledges that much more remains to be investigated.
Economic Importance
Aquatic organisms have emerged as an important source of food and work in Costa Rica. According to the United Nations Organisation for Food and Agriculture (FAO), in 2008 the production of white shrimp in America constituted 80 per cent of global aquaculture production of this species.
According to the Foreign Trade Corporation of Costa Rica (PROCOMER), the country exported a total of $ 5 million shrimp in 2011, 28 per cent more than the previous year, and in August 2012 exceeded $ 3 million dollars, 12 per cent more than the same period last year. Germany and the USA are listed as the main markets.
However, bacterial diseases such as Vibrio spiIn aquaculture production have generated significant economic losses.
June 2013
