Effects of dietary Pediococcus acidilactici GY2 single or combined with Saccharomyces cerevisiae or/and β-glucan on the growth, innate immunity response and disease resistance of Macrobrachium rosenbergii.
One Pediococcus acidilactici strain, named PA-GY2 was isolated from the gut of cultured Macrobrachium rosenbergii. In order to better examine the potential scope and applicability of this strain in M. rosenbergii culture, based on the control diet, four experimental diets containing single or combined immunostimulants were produced by supplementing with yeast (Saccharomyces cerevisiae, SC) or/and β-glucan (G), then fed to the prawns (6.70 g ± 0.74) in five groups, which were named as group C (control group), P (PA-GY2), PS (PA-GY2 + SC, 1:1), PG (PA-GY2 + G) and PGS (PA-GY2 + SC + G), respectively. After a 60-day feeding trial, growth performance, feed utilization, immune response and disease resistance of prawns were evaluated in the present study. Results indicated that (1) The growth performance of the prawns in group PS and PGS were significantly improved. The prawns in group PGS presented the lowest feed coefficiency (FC), while prawns in group C presented the highest FC. (2) The protease activity was significantly improved by dietary immunostimulants supplementation, meanwhile, prawns in the group PS presented the highest lipase activity. (3) The highest total hemocyte count and respiratory burst activity were found in the group P and PG, respectively. The phagocytic index of the prawns in the group C was significantly lower than those in group P and PGS. (4) Dietary PA-GY2 single or combined with SC or/and β-glucan increased the immune related genes expression, including some antibacterial and antioxidant enzymes, while decreased the tumor necrosis factor-α gene expression, which led to the decreased cumulative mortality rate of prawns during the Aeromonas hydrophila challenge test. Based on the results of growth performance, digestive enzymes activity and immune response of M. rosenbergii, PA-GY2 supplementation, single or combined with SC or/and β-glucan could be suggested as promising immunostimulants in prawns farming.