THE EFFECTS OF ADDING MICROBIAL BIOMASS TO GROW-OUT AND MATURATION DIETS ON THE REPRODUCTIVE PERFORMANCE OF BLACK TIGER SHRIMP, Penaeus monodon

To date, significant advances have been made in the domestication and genetic improvement of Penaeus monodon, include superior growth and feed utilization, increased harvest yields and increased viral tolerance. Despite these improvements, the reproductive performance of domesticated stocks remains inferior when compared with wild-caught broodstock. Recent innovation in the use of microbial biofloc technologies represents a potential avenue to improve reproductive performance in domesticated shrimp; however the use of 'live' biofloc is largely restricted to the grow-out phase only. An alternate approach is the inclusion of dried biofloc (microbial biomass) within shrimp feeds thereby allowing for biofloc substituents to feed across all stages of the lifecycle.

A 10-month semi-commercial trial was conducted to assess whether reproductive performance in domesticated stocks could be improved by supplementing grow-out and maturation diets with microbial biomass. Under a factorial design shrimp were fed on either a typical pelleted grow-out diet with or without microbial biomass, before being subset and allocated a control or biomass inclusive maturation diet (Figure 1). In total, broodstock were reared for 7 months on farm (growout phase), before being transferred to an off-site maturation facility. Females were conditioned for an additional 6-week before a 40-day reproductive performance trial was undertaken.   

No significant differences in maturation rate, or egg and nauplii production parameters were found between diet treatments (p=>0.05) (Table 1). However, the percentage of eggs that hatched was lower in females fed a MB-inclusive maturation diet (p=<0.05). These results indicate that the inclusion of microbial biomass within broodstock grow-out and maturation diets (at the rates presented) did not enhance reproductive performance of domesticated broodstock. Whilst growout supplementation did not appear to significantly influence subsequent reproductive performance; the use of microbial biomass supplementation in low-density broodstock ponds may require further assessment.