Dietary contribution of fermented grain pellets to the growth of juvenile Litopenaeus vannamei raised in an intensive biofloc-based rearing system

This study investigated the dietary contribution of fermented grain pellets (FGP) to the growth of juvenile Litopenaeus vannamei raised in a biofloc-based system. Grain pellets made of agricultural plant by-products were fermented with distilled water containing dehydrated live probiotic yeast, Saccharomyces cerevisiae. Shrimp were fed a feed with 396.8 g kg−1 crude protein (CP) under the following proportions: 100:0 (percentage of feed and FGP to the total daily ration, respectively), 75:25, 50:50, 25:75, and 0:100. Juvenile shrimp of 1.15 ± 0.12 g were stocked under 133 animals m−2 and reared for 77 days in thirty-five 1-m3 outdoor tanks. Final shrimp survival reached 89.3 ± 5.7% and was unaffected by dietary treatment. Shrimp body weight decreased significantly from 12.68 ± 1.48 (100:0) and 11.71 ± 0.67 g (75:25) to a low of 5.23 ± 0.40 g (0:100). No differences were found in weekly shrimp growth between shrimp fed under 100:0 (1.06 ± 0.14 g) and 75:25 (0.97 ± 0.06 g). Feed replacement at 25% caused no loss in yield (1,290 ± 87 g m−2) compared to no feed replacement at all (1,365 ± 148 g m−2). The 75:25 proportion of feed to FGP was able to partially spare feed inputs leading to 0.08 USD kg−1 savings in feeding costs. Results indicated that a feed replacement of 25% compensated by an equivalent amount of FGP as part of the daily ration led to no detriment in shrimp growth performance in a biofloc-based system.