Análisis de la carga de vibrio sp. en postlarvas de litopenaeus vannamei sostenidas con alimento aritifical y 1g/l de biomasa durante 6 horas

Abstract

This study was carried out to evaluate the effect of artificial feed on the concentration of Vibrio sp. bacterial load in Litopenaeus vannamei postlarvae during simulated transport from the laboratory to shrimp farms. The research was carried out at the Plant Health Laboratory of the Technical University of Machala, using six-day-old postlarvae collected in Puerto Bolivar. To simulate transport, containers with 1 litre of water were used, maintaining a density of 1g/L of postlarvae, equivalent to 572 postlarvae per litre. Two treatments were carried out: one with feeding and one without feeding. In the fed treatment, balanced flake feed was provided three times during the six hours of the experiment. Vibrio sp. bacterial load was measured in both water and postlarvae at baseline, 2, 4 and 6 hours, using TCBS Agar for the detection of Vibrio sp. Postlarvae were measured individually, with an average size of 7.6 ± 1.08 mm. The average wet weight was 572 postlarvae per gram. The initial Vibrio sp. concentration was 150 ± 121.24 CFU/ml in the postlarvae and 6.6 CFU/ml in the water. In the fed treatment, the bacterial load in the water increased by 92.16% at 2 hours, decreased by 71.93% at 4 hours, and increased again by 65.96% at 6 hours. In the postlarvae, the bacterial load initially decreased by 7%, then by 81.62%, and finally increased by 58%. These results suggest significant fluctuations in bacterial load due to the presence of feed. In the unfed treatment, the bacterial load in the water increased by 91.67% at 2 hours, decreased by 81.25% at 4 hours, and increased by 42.86% at 6 hours. In the postlarvae, the bacterial load showed a similar pattern, with a 40.26% decrease at 4 hours and a 54.36% decrease at the end of the experiment. A positive correlation was observed between the concentration of Vibrio sp. in the water and in the postlarvae (correlation coefficient of 0.8421), indicating that the presence of bacteria in the water is reflected in the postlarvae. The presence of feed increased the concentration of Vibrio sp. in the water 2.5 times higher than in the treatment without feed, and in the postlarvae, the concentration was 2 times higher. The results suggest that Vibrio sp. load tends to decrease in the presence of fresh water and oxygen saturation, but increases slightly after six hours, indicating that bacterial growth may continue if exposure time is extended. The non-feeding treatment showed a continuous decrease, suggesting that it could be a viable strategy to control bacterial load during transport. In conclusion, the study highlights the importance of biosecurity practices and feed control during transport of postlarvae to minimise the risk of disease outbreaks. Proper management of transport conditions, including feed regulation, can significantly reduce the bacterial load of Vibrio sp., improving the health of postlarvae in shrimp farms