Introduction: This paper discusses the results of two tank-based studies carried out at the Andaman Aquatic Research Centre (AARC) in Thailand testing the effects of Novacq™ microbial biomass on growth, survival and FCR of P. vannamei fed commercial diets containing varying levels of this ingredient in its original form: NovacqTM, and an improved form produced by Ridley called NovaqPro®.
Methods: Trial 1 was conducted in a 76 * 200 litre tank system stocking shrimp juveniles of 0.7g initial weight, which were fed 19 high quality iso-nitrogenous and iso-calorific diets per trial with 4 reps per treatment for 6 weeks to apparent satiation. Trial 1 used varying levels (2.5-15%) of 3 different types of dried NovacqTM powder (original CSIRO NovacqTM, Thai and Australian produced NovaqPro®), replacing wheat flour in otherwise similar diets. Trial 2 used the same system, stocking 0.6g juveniles, using 4 replicates of 7 treatments in 28 tanks, fed for 6 weeks. A high quality Ridley diet (43% protein) was used with and without 5, 7.5, or 10% of 2 different autoclaved Novacqs™: 1 original Novacq™ from CSIRO and 1 NovaqPro® type of NovacqTM developed and produced by Ridley in Australia. Results were analysed by two-way ANOVAs with NovacqTM treatment and inclusion rate as factors. Significant differences against the control diet were tested by one-way ANOVAs and post-hoc comparisons using Dunnett’s two-sided multiple-comparison test.
Results: Trial 1 showed that shrimp accepted all feeds with survival above 91% across dietary treatments. Production performance metrics were statistically affected by Novacq™ type and inclusion levels with all microbial biomass treatments significantly outperforming the control. Thai and Australian-produced NovaqPro® were similar and outperformed the original NovacqTM. Generally, there was a direct correlation between NovaqPro® inclusion level and growth, which was increased by up to 58% over the non-microbial biomass control diet at a 12.5% inclusion level, whilst original NovacqTM increased growth rate by up to 35% over the control. Trial 2 again showed an average 94% survival and good growth. Results showed that there was a generally direct relationship between NovacqTM inclusion level and shrimp growth rates for the two types of NovacqTM. However, this was most pronounced for the Ridley NovaqPro®, which, even when autoclaved, increased growth rate by 24% over the control at 5%, rising to 33% at 7.5-10% inclusion, which was 31-45% better than that achieved by the autoclaved original NovacqTM.
Conclusions: Use of dried NovaqPro® microbial biomass powder has been shown to increase growth (with little effect on survival or FCR) in direct relation to dietary inclusion rates by up to 58% at up to 12.5% inclusion in high quality Australian diets under laboratory conditions. When this product was autoclaved to sterilize it, relative performance decreased, but was still highest for the modified and improved Ridley NovaqPro® version, which promoted growth at significantly greater rates than that of the original NovacqTM. The new NovaqPro® microbial biomass has thus been shown to be a significant improvement over the original NovacqTM microbial biomass product.