Impacts of Dietary Supplementation of Peptidoglycan Extracted from Lactobacillus sp. on the Growth Performance and Resistance to Streptococcus Agalactiae of Nile Tilapia

Abstract

The current experiment aimed to determine the effects of peptidoglycan, known as a prebiotic compound, on the growth, feed efficiency, and disease resistance in Nile tilapia. Fish at an initial body weight of 22.6 ± 0.3g were distributed into a 100 L-glass tank system. Peptidoglycans extracted from Lactobacillus sp. were added to commercial feed at ratios of 0, 5, and 10 g kg-1 diet corresponding to the PG0, PG5, and PG10 treatments, respectively. Fish were then fed at 4% their body weight for four weeks. After a 4-week trial, fish were infected with Streptococcus agalactiae at 50% the lethal dose (1.1×106 CFU mL-1), and monitored for 14 days. After 2 and 4 weeks of the feeding trial (T2 and T4) and on the second day of the bacterial challenge, fish blood samples were collected for hematological analysis. The results indicated that the dietary supplementation of peptidoglycan induced a positive effect on fish growth performance and the highest value was observed in the PG5 treatment. The lowest value of cumulative mortality was also observed in the PG5-fed fish indicating that the dietary supplementation at 5 g kg-1 diet supported the highest resistance to S. agalactiae. In conclusion, the beneficial effects of dietary supplementation of peptidoglycan extracted from Lactobacillus sp. were recorded on the growth performance and disease resistance in Nile tilapia.