Survival and Immunity of Marron Cherax cainii (Austin, 2002) Fed Bacillus mycoides Supplemented Diet under Simulated Transport

Abstract

The present study examined the effect of simulated transport on marron, Cherax cainii, (Austin, 2002) after a 10 week feeding trial using basal diet or customised probiotic, Bacillus mycoides supplemented diet by measuring intestinal bacterial population, total haemocyte count (THC), bacteraemia, morbidity, dehydration and mortality. Packing steps followed the established standard packing method for live transportation of marron. Each treatment group consisted of six polystyrene boxes (65 × 30 × 40 cm3), and each box contained 30 marron from each feeding group. The sealed boxes were placed on a trolley at room temperature to give the effect of transportation. Boxes were opened at 24th and 48th hour post simulated transport and marron from each treatment group were returned to the culture tank. After temperature acclimation, the marron were observed for mortality and samples were collected to assess marron health and immunity. The results demonstrated that no mortality was observed at 24 h of transport both in basal diet and probiotic diet fed marron, however at 48h of transport the survival of probiotic fed marron was significantly higher (100 ± 0.0%) compared to survival (93.3 ± 2.8%) of basal diet fed marron. The higher survival rate of probiotic fed marron was also sustained by superior health and immune status indicated by higher intestinal bacterial population, higher total haemocyte count and lower haemolymph bacteria (bacteraemia) level. In brief, supplementation with host origin customized probiotic B. mycoides significantly improved marron tolerance to a live transport stress test, which resulted in no mortality up to 48h of transport.