Disease resistance of Pacific white shrimp, Litopenaeus vannamei, following the dietary administration of a yeast culture food supplement

A yeast culture feed supplement (Diamond V XP Yeast CultureR, Diamond V Mills, Cedar Rapids, Iowa [IA]) was assessed for its impact on disease resistance in the Pacific white shrimp, Litopenaeus vannamei. Animals were fed a standard shrimp pellet diet supplemented with 0% (control with 1% grain carrier), 0.5% (with 0.5% carrier), or 1.0% XP daily for 4 weeks. To assess resistance to bacterial disease, at 1-week intervals 21 shrimp (0.5–2.5 g) from each test diet were injected intramuscularly with an LD50 dose (2.0 10/g body weight) of a gram-negative shrimp pathogen, Vibrio sp. 90-69B3. Survival was monitored every 4 h for 48-h post injection. Each week, three independent bacterial challenges were performed for each diet and the results expressed as the mean percent survivalF standard error (S.E.). A two-way analysis of variance (ANOVA) showed a significant effect of diet ( p = 0.003, df = 31), but not duration of feeding, on survival. A one-way ANOVA showed no differences among the treatment groups after 1 or 2 weeks. After 3 weeks, the mean survival of 1% XP-fed shrimp (74.2F 1.4%) was significantly higher than that of controls (42.9F 5.5%), while mean survival of shrimp fed 0.5% XP (54.8F 11.9%) was not significantly different from controls. After 4 weeks, mean survival of 1.0% XP-fed shrimp (63.4F 8.8%) remained higher than that of controls but the difference was not significant ( p = 0.07). An insufficient number of animals were available from the 0.5% XP-fed group to perform bacterial challenges at this timepoint. Mean survival of control shrimp declined significantly over the 4 weeks of study (slope of linear regression p 0, p = 0.005, df= 11), but no decline was observed in animals fed the 0.5% or 1.0% XP diets. After 4 weeks L. vannamei fed standard shrimp pellets, 0% XP control, or 1.0% XP diets showed no significant differences in weight, suggesting that the changes in disease resistance did not correlate with changes in growth rate among the treatment groups. These 0044-8486/$ see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.aquaculture.2003.09.003 * Corresponding author. Tel.: +1-843-953-9171; fax: +1-843-953-9199. E-mail address: [email protected] (K.G. Burnett). J.E. Burgents et al. / Aquaculture 231 (2004) 1–8 2 results indicate that dietary administration of Diamond V XP Yeast CultureR can protect shrimp against a decline in resistance to bacterial disease. D 2004 Elsevier B.V. All rights reserved.