Efecto del extracto de oreganón (plectranthus amboinicus) en fresco, aplicado sobre la dieta para la reducción vibrios spp en litopenaeus vannamei

Abstract

In recent years, there has been evidence of increased production in the aquaculture sector, where in 2018 a total of 82.1 million tons of production aquatic organisms were obtained in the world, of crustaceans obtained 9.4 million tons and 52.9% were white shrimp. One of the main challenges in shrimp farming is vibriosis, a bacterial disease caused by the genus Vibrio, which has led to considerable economic losses. Vibrio harveyi is identified as the most aggressive pathogen responsible for acute hepatopancreatic necrosis, known as early mortality syndrome, one of the most persistent threats in the shrimp industry. The use of antibiotics in aquaculture has been regulated according to international standards. In Ecuador, antibiotics such as florfenicol and oxytetracycline are used to combat vibriosis. However, inappropriate use of oxytetracycline has led to bacterial resistance. As an alternative, essential oils from medicinal plants, which possess antimicrobial properties and are biodegradable, are being used. One prominent plant is Plectranthus amboinicus, known for its antimicrobial activity and therapeutic properties, which is found in tropical and subtropical regions. This plant contains bioactive compounds that offer benefits in the fight against diseases in shrimp farming, representing a viable option to antibiotics. The objective of this research is to evaluate the effect of oreganon (Plectranthus amboinicus) extract in fresh form, applied on the diet for the reduction of Vibrio spp in L.vannamei. To achieve the stated objective, a series of experiments will be carried out under both in vitro and in vivo conditions. This will include extensive investigations on the optimal dosage of the compounds in question, evaluating both their toxicity and inhibitory capacity. The purpose of these studies is to determine the appropriate dosage that will prevent harmful effects to the shrimp, while maintaining efficacy in disease treatment. For this experiment, two treatments and a control group were implemented, each with three replicates, (T0: Only balanced feed was provided; T1: Balanced feed with 0.25% oreganon extract + glue; T2: Balanced feed with 0.50% oreganon extract + glue). Forty-five L. vannamei organisms were randomly placed and fed at 4% of their biomass twice a day. Water was changed every 3 days at 30 % and parameters such as temperature (26.5±0.5 °C), ammonium (0.010±0.004 mg/L) and pH (6.28±0.08) were monitored. The results obtained from the experiment where both treatments obtained a reduction of 98.8% and 83.33% in the bacterial load of Vibrio. Likewise, an optimal growth was observed with the use of oregano extract where the Control treatment showed an average growth of 3.07g, T1 of 3.12g and T2 of 3.23g.