Effectiveness of crude extracts from common indigo (Indigofera tinctoria L.) in inhibiting Streptococcus agalactiae in Nile tilapia

Document Type : Original research

Authors

• Patcharawalai Sriyasak ¹
• Naiyana Senasri ¹
• Nattiya Chumnanka ¹
• Pongsathorn Tongkasee ²
• Wasana Phlaetita ³
• Pornpimol Pimolrat ⁴
• Supannee Suwanpakdee ¹

¹ Department of Fisheries, Faculty of Natural Resources, Rajamangala University of Technology Isan Sakon Nakhon Campus, Sakon Nakhon 47160, Thailand

² Department of Thai traditional medicine, Faculty of Natural Resources, Rajamangala University of Technology Isan Sakon Nakhon Campus, Sakon Nakhon 47160, Thailand

³ Department of Plant science, Faculty of Natural Resources, Rajamangala University of Technology Isan Sakon Nakhon Campus, Sakon Nakhon 47160, Thailand

⁴ Department of Coastal Aquaculture, Faculty of Maejo University at Chumphon, Maejo University, Lamae, Chumphon

10.22034/iar.2023.1986215.1443

Abstract

The Nile tilapia (Oreochromis niloticus) culture is particularly susceptible to disease outbreaks, particularly infection by Streptococcus agalactiae bacteria. This study aimed to determine the efficacy of extracts of common indigo (Indigofera tinctoria) in inhibiting S. agalactiae. A completely randomized design (CRD) was carried out using pellet feed sprayed with varying concentration levels of the indigo extract: 0%, 0.1%, 0.5%, and 1%. The sample received the feed for eight weeks. The samples were analyzed to evaluate the effect of common indigo extract on growth performance, hematological parameters, biochemical parameters, and lysozyme activities. The results showed that the Nile tilapia fed pellet feed sprayed with 0.5% concentrated indigo extract exhibited the highest inhibition of S. agalactiae. The hematology results showed statistically higher (p<0.05) total red blood cells, hemoglobin counts, and hematocrit in the sample fed the pellet feed sprayed with the indigo extract than those in the control group. The sample fed pellet sprayed with 0.5% concentrated indigo extract exhibited statistically higher (p<0.05) white blood cells and a higher percentage of lymphocytes than those in other groups. In terms of biochemistry in blood, the sample fed pellet feed sprayed with 1% concentrated indigo extract exhibited statistically higher aspartate aminotransferase (AST) than those in other groups. The sample fed pellet feed sprayed with 0.5% and 1% concentrated indigo extracts exhibited statistically higher alkaline phosphatase (ALP) and total protein than those in other groups. Immunity test in blood showed that the sample fed pellet feed sprayed with 0.5% concentrated indigo extract exhibited statistically higher lysozyme in serum than those in other groups. The sample that was fed pellet feed sprayed with 0.1% and 0.5% exhibited statistically higher (p<0.05) immunoglobulin M levels than those in other groups. Overall, this study showed that the indigo extract could inhibit S. agalactiae and increase immunity in Nile tilapia.

Keywords

• Common indigo
• Streptococcus agalactiae
• Immunity
• Nile tilapia

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