Probiotic Applications in Crustaceans - Aquaculture Nutrition: Gut Health, Probiotics and Prebiotics - page 308

their high protease, carbohydrolase and lipase activities which they suggested could be used as
probiotic in order to increase feed utilization by the shrimp. Recently, Liu etal. (2009) isolated
a protease-producing bacterium ( B. subtilis E20), and demonstrated that, when administered
to shrimp juveniles at 10 8 CFU kg -1 of feed, this probiotic improved growth performance
and increased protease activity in the digestive tract of the shrimps. Ziaei-Nejad et al. (2006)
also associated the growth improvement of the F. indicus shrimp, cultured with mixed Bacil-
lus probiotics, with an increase in the specific amylase, lipase and protease activities in the
digestive tract. However, based on the low colonization rate of the Bacillus strain in the diges-
tive tract of the shrimps, the authors suggested that the exogenous enzymes produced by the
probiotic strains may account for only a small proportion of total enzyme activity. Therefore,
in order to explain the improved growth rate and FCR recorded in the probiotic treatments,
the authors assumed that the probiotic might stimulate endogenous enzymes produced by the
shrimp. Other studies suggest the same hypothesis (Wang 2007; Castex et al. 2008) and Wang
(2007) reported that these effects were not improved by increasing concentration, suggesting
that such probiotic effect could reach an upper limit in the shrimp intestine.
Additional studies are required to better understand the contribution of probiotics to nutri-
tion, and their potential to address the challenges of the next generation of feeds that would
likely use more complex formulations (using the growing range of raw materials available in
the market) in order to avoid the dependence on particular raw materials
11.4 RELATED BENEFITS IN CRUSTACEAN AQUACULTURE
Despite a lack of precise understanding of the mechanisms behind the use of probiotics, many
studies and field reports provide evidence of the efficacy of the probiotic concept in crus-
taceans. The following benefits have been extensively reported: improved disease resistance
(against bacterial and viral diseases), immune response, health status, growth performance,
feed utilization, and modulation of the intestinal microbiota. Tables 11.1 and 11.2 present
a summary of some of the most relevant in vivo probiotics studies published with crustacean
species, for larvae, early post larvae and larger developmental stages (juveniles and sub-adults).
Regarding shrimps, although most of the trials on larvae, post larvae, juvenile, sub-adult and
breeder shrimps were carried out with the black tiger ( P. monodon ) and white shrimp ( L. van-
namei ), a substantial number of studies have also taken place on marine and freshwater shrimp
species such as F. chiniensis , F. indicus , L. stylirostris and Macrobrachium rosenbergii .
Indeed, unlike finfish aquaculture, the use of probiotics in crustacean culture, specifically
shrimp culture, is now a common and widely adopted management practice used by farmers.
Therefore, some practical considerations and issues regarding large scale experiments are pro-
vided in the following sections.
11.4.1 Main benefits reported in larvae and early post larvae
stage
11.4.1.1 Overview
Maeda and Liao (1992) were the first to report the beneficial effect of bacterial strains on
penaeid shrimp larvae. This study demonstrated that a soil bacterial strain ( Thalassobacter
utilis PM-4), with invitro inhibitory activity against V.anguillarum , was able to increase larvae