Effects of dietary supplementation with probiotics on growth performance, gut health and disease resistance of striped catfish (Pangasianodon hypophthalmus)

This study was conducted to investigate the effects of the probiotic (Bacillus Liq-Vtech)-supplemented diets on growth performance, intestinal microbe, morphology of the intestine, and resistance to Edwarsiella ictaluri infection in striped catfish (Pangasianodon hypophthalmus). A total of 800 healthy striped catfish (12 ± 2 g) were randomly divided into four experimental groups with four replicates each, and were fed diets supplemented with different levels of Bacillus Liq-Vtech (T1: 0 cfu/g; T2: 0.5 × 106 cfu/g; T3: 1.0 × 106 cfu/g; and T4: 1.5 × 106 cfu/g) for 8 weeks. At the end of the trial, a challenge test with Edwardsiella ictaluri was conducted for 2 weeks. The results showed no statistically significant improvement in the growth performance and survival rate of fish with Bacillus LiqVtech supplementation (P > 0.05). However, there was a tendency for the improved growth performance in treatments supplemented with Bacillus Liq-Vtech. Additionally, the density of Bacillus spp. increased in the intestinal tract of fish fed probiotic-supplemented diets compared with the control. All probiotic treatments exhibited positive effects for different histomorphological features of the intestine. Mucus secreting goblet cells and villi increased in probiotic-supplemented groups. Mortality rates in treatments supplemented with Bacillus Liq-Vtech were lower than those of the control. These results suggested that the Bacillus Liq-Vtech supplementation in diets has the potential to improve growth performance, increase beneficial bacteria in the intestinal tract of the fish, and reduce the mortality of striped catfish after being challenged with Edwardsiella ictaluri.