Immunological and Bactericidal Effects of Turmeric (Curcuma longa Linn.) Extract in Pacific White Shrimps (Litopenaeus vannamei Boone)

Abstract

Pacific white shrimp (Litopenaeus vannamei Boone) has been one of the main export agricultural products of Thailand. However, culture of this marine shrimp has been retarded continuously by disease problems that have lead to a decline in production or even the collapse of the farming system in some areas of the country. To cope with the disease outbreaks, some farmers apply antibiotics, which can cause negative consequences to shrimp products involving drug residues. In this study, turmeric (Curcuma longa Linn.) extract containing 25.726% (w/w) curcuminoids was added to shrimp feed as an immunoenhancement. Shrimp with an average weight of 12 g were raised with feed containing turmeric extract at 0, 12.5, 25.0 and 50.0 mg/kg feed (ppm). The studied parameters included resistance against pathogenic Vibrio harveyi, immune functions and the total count of bacteria from the shrimp intestines. The results showed significantly (P<0.05) better resistance against V. harveyi in shrimps fed with 25 mg/kg feed of turmeric extract when compared with control. Phenoloxidase activity of shrimps fed with 25 and 50 mg/kg feed of turmeric extract was significantly (P<0.05) higher than the control. All turmeric extract-treated shrimps showed higher bactericidal activity than the control. However, no significant (P>0.05) differences were found amongst the values of total haemocyte count and percent phagocytosis. Total bacteria and the Vibrio spp. count from the intestines of shrimps fed with turmeric extract at all concentrations were significantly (P<0.05) lower than the control.