Field testing of dual-species synbiotic microcapsules during IMNV disease outbreak and fluctuate weather: growth performance and immune response in Pacific white shrimp (Litopenaeus vannamei)

Abstract

This study aimed to evaluate the effectiveness of synbiotic microcapsules through feed on growth performance and immune response of Pacific white shrimp (Litopenaeus vannamei) in field testing during IMNV disease outbreaks and fluctuating weather. Four groups of shrimps (4.11 ± 0.05 g) with four replicates were fed with different doses of synbiotic microcapsules SIN 0 (0%), SIN 0.5 (0.5%), SIN 1 (1%), and SIN 1.5 (1.5%) for 60 days with a feeding frequency of 4 times a day (07.00, 11.00, 15.00, and 19.00) based on a feeding rate from 4% (w/w) for average body weight < 4 g, 3% (w/w) for average body weight 4–10 g, and reduced until 2% (w/w) for average body weight 10–25 g, depending on the feed index adapting to operational standards procedures for Pacific white shrimp cultivation production from PT Steladus. The synbiotic microcapsules consisted of prebiotic mannan oligosaccharide/MOS, probiotic Pseudoalteromonas piscicida (1UB), and Bacillus cereus (BR2). This study focused on parameters of growth performance (survival rate/SR, specific growth rate/SGR, feed conversion ratio/FCR), immune response (total hemocyte count/THC, differential hemocyte count/DHC, respiratory burst/RB, phenoloxidase/PO activity, phagocytic activity/PA), microbiology (total bacterial count/TBC, 1UB + BR2 Tet^R count, total Vibrio count/TVC), and histopathology. The results showed significant results that synbiotic microcapsules increased SR, SGR also reduced FCR with the best results in SIN 1.5 (SR: 93.50 ± 1.30%, SGR: 4.83 ± 0.01% days⁻¹, and FCR: 1.16 ± 0.02). Immune response of THC, RB, PO, and PA in the synbiotic microcapsule treatment showed higher values with the best results in the SIN 1.5 treatment, while DHC had no significant difference. TBC, 1UB, and BR2 Tet^R count values increased until the 60th day, with the highest value in the SIN 1.5, while TVC showed the lowest value in both intestinal and hepatopancreas organs. Histopathological results showed that hepatopancreas and intestinal organs experienced tissue damage in all treatments, with synbiotic microcapsules showing less damage when compared to SIN 0. In conclusion, supplementation of dual-species synbiotic microcapsules through feed can improve growth performance and immune response and suppress Vibrio during the outbreak with the best dose of 1.5% synbiotic microcapsules.