The threat of disease in the aquaculture industry, coupled with greater restrictions or ban on antibiotic use, has
increased interest in evaluating antibiotic alternatives. A promising alternative is organic acids, which have
been used for decades in the livestock feed industry as an antimicrobial and growth promoter. However, very
limited information exists on their applications to the shrimp aquaculture industry. The aim of the current
study was to examine the potential beneficial effects of a novel microencapsulated organic acid blend (OAB) to
the production of tiger shrimp, Penaeus monodon, in earthen ponds at a commercial farm when fed commercial
feedswithout (Diet A) orwith (Diet B) organic acid supplementation at 2% OAB throughout the grow-out period.
Farm-raised shrimpwere randomly sampled and transferred to the laboratory to examine any effects on nutrient
utilization, resistance of shrimp to Vibrio harveyi and associated hepatopancreatic histopathology and
phenoloxidase (PO) activity. Results showed that after 22 weeks of culture in ponds, shrimp growth was similar
between treatments. Lower nitrite-N and nitrate-N concentrations in the pond water indicated potential improved
protein utilization fromshrimp fed Diet B. Thiswas supported by data fromthe digestibility trial, demonstrating
crude protein, but also drymatter, ash and phosphorous utilization was significantly enhanced (P b 0.05).
Total viable bacteria and presumptive Vibrio spp. countswere lower at the end of the grow-out period in the pond
water of shrimp fed Diet B. Shrimp fed Diet B showed significantly higher survival to V. harveyi challenge, likely
due to enhanced PO activity and less hepatopancreatic damage. Total viable bacterial and Vibrio counts in the
hepatopancreas of shrimp fed Diet B were significantly lower compared to Diet A. This study provides the first
reported data on the use of dietary organic acids in a commercial shrimp farm setting. The enhancement to
nutrient utilization may reduce feeding costs and improve water quality while the higher resistance of shrimp
to pathogenic bacteria such as Vibrio spp. may provide shrimp farmers with an effective method to mitigate
disease outbreaks in the global shrimp aquaculture industry.
© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license