New bacterial meal may help promote robust immune response in shrimp
The study, published in Frontiers in marine sciences, And led by Dr Orapint, Department of Aquaculture, Faculty of Fisheries, Kasetsart University, Bangkok, reported that meal from methanotrophic bacteria can fully replace fish meal in white shrimp diets.
At a 15% inclusion rate, FeedKind in shrimp diets, the researchers said, showed no adverse effects on growth performance, feed utilization, and survival rate.
In addition, they noticed shrimp in the to study, Which was funded by Calysta, has demonstrated increased tolerance to the disease when faced with V. parahaemolyticus, The causative agent of early mortality syndrome (EMS), indicating that the bacteria’s meal protein may help promote a robust immune response.
EMS is one of the biggest issues facing shrimp farming today, having cost the industry billions of dollars since it was first identified in Asia in 2009.
The growth test consisted of four treatments and five repeats of each:
- T1: a fishmeal-based control containing 15% fishmeal and 3 diets with graduated levels of methanotrophic bacteria meal.
- T2: 5% flour from methanotrophic bacteria
- T3: 10% flour from methanotrophic bacteria
- T4: 15% flour from methanotrophic bacteria.
The authors explained that the shrimp were fed ad libitumfor six weeks on test diets to assess growth.
After the growth test, three replicates of the same groups were exposed to V. parahaemolyticusby a single bath challenge and maintained for an additional 15 days on the same regimens as the growth study to assess survival and resistance, the researchers said.
No significant difference in survival or growth performance including final weight, weight gain, specific growth rate, feed consumption or FCR of white shrimp fed feed containing methanotrophic bacteria meal or control diets for six weeks.
Immune markers such as hemocyte count, phenoloxidase, superoxide dismutase, and lysozyme activity were similar in all groups after the six-week feeding trial, the team noted.
They said that in the V. parahaemolyticuschallenge, the flour of methanotrophic bacteria in the diet significantly promoted the survival rate and reduction of Vibrio sp.in the hepatopancreas of white shrimp.
âHemocyte count and phenoloxidase activity showed no significant difference between treatment-by-diet groups, but hemolymph protein was significantly higher in shrimp-fed diets containing 15% of the meal. of methanotrophic bacteria after challenge. ”
The VibrioThe number of hepatopancreatic colonies in the treatment groups were all significantly lower than in the control, they added.