13
Figure 1. Comparative of hepatopancreas structure Liptofry (left) vs control (right). Challenge against Vibrio parahaemolyticus AHPND. Infective dose: 105 CFU/mL.
FCR
Mortality (%)
Liptofry
0.78 15.72
Control
0.92 27.09
Table 3. FCR and mortality rate (%) of rainbow trout field test.
The product development was based on a scientific approach. First, the antibacterial activity efficacy was evaluated in vitro by minimal inhibitory concentration test following the microdilution method (Table 1).
Shrimp lab test To satisfy shrimp’s needs, a specific product was designed to control Vibrio load and boost hepatopancreas function. Laboratory test achieved important reduction of green colony Vibrio count (decrease of 77,96% vs control) and lower degree of sloughing of hepatopancreas (Fig. 1). Rainbow trout lab test Liptofry was orally administered to rainbow trout fingerlings throughout weaning and nursery stages to check the improvement of disease resistance against Flavobacterium psychrophilum.
Fingerlings were infected by intraperitoneal injection with Flavobacterium psychrophilum RBT4.1.04 (average weight of 5.84±1.29 g). A control group fed on a standard diet was also challenged. Mortalities started 24 hours post-infection and ceased after 4 days in both groups (Table 2). Mortality rate of control group (62%) was significantly higher than the one fed on phytobiotics (27%, ANOVA p<0,05). The use of feed supplemented with phytobiotics as Liptofry in rainbow trout may contribute to the prevention of diseases caused by Flavobacterium psychrophilum due to the combined effect of the high antimicrobial activity of the nutraceutical against F. psychrophilum and the ability of nutraceuticalsupplemented diets to stimulate parameters of the specific and non-specific immune response of rainbow trout.
Field trials Several field trials were carried out in shrimp hatcheries and nurseries to control Vibrio population. The phytobiotic boosts shrimp’s energy consumption making them more resistant to stress and help them to molt.
Figure 2. Mortality evolution during the three-month rainbow trout field trial.
Hatcheryfeed Vol 7 Issue 4 2019