February 15-18, 2009 Washington State Convention Center Seattle ...

3 2
SUPPLEMENTAL NUTRITION PROVIDED TO PACIFIC WHITE SHRIMP Litopenaeus
vannamei BY NATURAL PRODUCTIVITY FROM EITHER A PHOTOAUTOTROPHIC OR A
HETEROTROPHIC HYPER-INTENSIVE ZERO-EXCHANGE BIOFLOC SYSTEM
Jesus A. Venero*, John Leffler, A.O. Galvez, Jason Haveman, Alisha Lawson, Andrew Shuler, Beth Thomas,
L. Vinatea and Craig L. Browdy
SCDNR - Waddell Mariculture Center
211 Sawmill Creek Road
Bluffton, SC 29910 USA
VeneroJ@dnr.sc.gov
Hyper-intensive zero-water exchange biofloc systems technologies are being developed to make the USA shrimp industry more
competitive. These systems support a diverse microbial community that has been shown to enhance shrimp growth and to
provide essential nutritional components. The nature of these enhancement factors is still uncertain, although a direct association
with marine microalgae, especially chlorophytes and diatoms, is suspected. A study was conducted in order to evaluate
the supplemental effect of natural productivity on Pacific white shrimp, L. vannamei, nutrition in zero-water exchange, high
intensity shrimp raceways. Two 50-m 2 greenhouse enclosed raceways were stocked with juvenile shrimp at 100/m 2 . One
raceway received direct sunlight leading to considerable photoautotrophic activity and the other was completely covered with
black polyethylene, blocking sunlight and creating a heterotrophic biofloc system. Water from each raceway was pumped
continuously through two different rows of sixteen 60-L glass tanks each located in an adjacent greenhouse. A third row of sixteen
glass tanks operating on a filtered UV-treated seawater recirculating system served as controls. Shrimp within each water
system were assigned to one of four 36%-crude protein diets: a fishmeal-based diet, an all-plant diet with DHA-AA and vitamin
supplementation, an all-plant diet without DHA-AA supplementation, and an all-plant diet without vitamin supplementation.
Each tank was stocked with 15 shrimp (0.79±0.03 g).
ANOVA analyses demonstrated no significant differences (P>0.05) among final weights or feed conversion ratios (FCR) for
shrimp raised in the three water systems when the DHA-AA deficient diet was fed. However, the same variables were significantly
improved (P≤0.05) for shrimp raised in the heterotrophic system than for shrimp raised in the other systems when the
other diets were fed (0.81 g/wk vs. 0.57-0.59 g/wk and 1.36 vs. 1.89-1.93, for weight gain/week and FCR respectively). Shrimp
consumed less than 50% of the total daily ration for all the diets, possibly due to poor palatability caused by a bad ingredient.
Apparently shrimp could not compensate for a dietary deficiency of DHA-AA by consuming biofloc when the food allowance
was reduced. However the heterotrophic biofloc apparently negated ill effects from the vitamin deficient diet. Better
growth performance and FCR ratios were observed when complete diets were fed in a heterotrophic system. Shrimp raised
in the autotrophic system had values comparable with shrimp raised in the clear water system, both significantly poorer than
those of the heterotrophic water. Currently this experiment is being repeated under similar conditions with enhancement of the
photoautotrophic system through periodic inoculation with microalgae of the genus Thallasiosira sp (pelagic) and Navicula sp
(bentonic).