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Preventing monogenean
gill parasites
in marine fish
APEX BRANCHIA C
Introduction
• Parasitism : symbiotic relationship where one organism, the
parasite, benefits at the expense of the other, the host
• Often complex life cycles
• Abundant in nature
• Most are microscopic and difficult to diagnose
• Aquaculture : increasing economic impacts from parasitic
infestations
• Intensification of production system
• Secondary bacterial infections or parasites causing mortality
• Affecting final product quality (eg sealice, gill color)
Important parasites in Aquaculture
PROTOZOA: single cell• Ciliates, eg I. multifiliis white spot
• Flagellates
• Microsporidae: intracellular parasites
• Coccidae: intracellular parasites
• Myxosporidae: endo parasites
PLATYHELMINTHES: flatworms• Monogenean trematodes (Flukes), eg Gyrodactylus
• Nematodes (Roundworms)
• Cestodes (Tapeworms)
PARASITIC CRUSTACEANS AND LEECHES: • Larger parasites, eg sea lice
Monogenean parasites (“gill flukes”) in marine fish
Important ectoparasites in marine and freshwater fish
Main species in Mediterranean marine fish:
Seabass:
• Diplectanum aequans
• Diplectanum laubieri
• Serranocotyle labracis
Seabream:
• Sparicotyle (syn. Microcotyle) chrysophrii
• Dactylogyrus (syn. Furnestinia) echeneis
Clinical signs:
• gill irritation and increased mucus production
• Loss of red coloration of gills
• Asphyxia (high level of infestation)
Light microscopic image of
Sparicotyle chrysophrii
Diplectanum aequans
Importance of prevention
Treatment
• Limitations of drugs and chemicals: • Difficult application (eg cage farming)
• Regulatory issues & consumer concerns
� Prevention strategies:• Bio-security & hygiene measures
• Balanced feed formulas & good farming practice
• Specific health promoting additives with natural anti-parasiticaction
• Direct action on gut parasites in the digestive tract
• Indirect action on ecto parasites: – Natural anti-parasitic compounds absorbed and circulating in
the blood stream
– Enhanced immune-response (eg. mucus quality & thickness)
Research on prevention of fish parasites through functional feed additives
COMPLEX !
• Many different species of fish and parasites
• Complex interactions (among different parasites, with
secondary bacterial infections, seasonal ambient
conditions, ...)
• Life cycles not fully understood
• Challenge protocols under lab conditions still under
development
• Lab results (in vitro or in vivo challenge) often not
reproducable under production conditions
Novel field of academic research
Prevention of monogenean gill parasites using natural additives: caprylic acid
Rigos et al. (2013)
1. Verification of absorption and circulation of the anti-parasitic
component administered through the feed:• Single in-feed administration of 100 or 200 mg/kg caprylic acid to Gilthead seabream
• Caprylic acid absorbed and circulating in the blood serum, present in skin and gills
Skin caprylic acid concentration
Gill caprylic acid concentration
Serum caprylic acid concentration
Prevention of monogenean gill parasites using natural additives: caprylic acid
FARM 1: prevention effective !low initial prevalence (44-47%)
and mean intensity (1.1-1.5 adults)
FARM 2: treatment not effectivehigh initial prevalence (100%)
and mean intensity (up to 17 adults)
Rigos et al. (2013)
2. Evaluating efficacy under farm conditions- Caprylic acid (200 mg/kg of feed) to Gilthead seabream cages during 60 d
- Monitor infection intensity Sparicotyle chrysophrii
Importance of synergistic action of botanical extracts
• Effects of single and combined use of two
herbal extracts to prevent Dactylogyrus on
goldfish (Carassius auratus)
• RDZ (Dioscorea zingiberensis)
• SGB (Ginkgo biloba)
• Measure anti-parasitic efficacy by exposing
infested fish to a range of concentrations
of herbal extracts
• Anti-parasitic Efficacy (48h EC50)
• Single components (SGB or RDZ):
3.5 mg/L
• Combination (SGB/RDZ 5:5):
1.5 mg/L
Jiang et al. 2014
3 fold decrease of effective dosage
thanks to synergistic action
Research on prevention of fish parasites through functional feed additives
• Complex
• New field of academic research
• Most studies focussed on single component additives
Nutriad’s approach:
• empiric work in the field with selected customers
or research institutes
• synergistic additive cocktails targeting multiple
mode of actions
Department of Fish Pathology, Faculty of Fishery,Nong Lam University of Hochiminh City, Vietnam
APEX AQUA enhances resistance to monogenean gill
parasites in Pangasius catfish (Pangasianodon
hypophthalmus)
(Coutteau, Nguyen Huu Thinh, Eskinazi and Huyen Dieu Nguyen
– Aquaculture Asia-Pacific, Sept-Oct 2010)
Nutriad’s innovative research on prevention of monogenean gill parasites
Monogenean gill parasites in Pangasius
Experimental Design & Pond Setup
• Triplicate cages (4x2 m) per
treatment
• Stocking Density: 80 fish/m2
(640/cage); fingerlings of 9-
11g live weight
• Experimental diets (extruded
commercial basal feed) fed
for 8 weeks
• Treatments
� Control: No Apex
� NT0.05: Apex 0.5kg/MT
� NT0.1 : Apex 1.0kg/MT
NT0.05 (3) Control (1) Control (3)
Control (2)
NT0.1 (2)
NT0.1 (3) NT0.05 (2)
NT0.05 (1) NT0.1 (1)
Results - Performance
Control Apex 0.5 Apex 1.0
Start Weight (g) 9.95a 9.90a 10.26a
Final Weight (g) 67.55a 69.92ab 71.36b
Weight Gain (g) 57.60a 60.02a 61.1a
Specific Growth Rate (%/day) 3.01a 3.05a3.13b
(+4%)
Feed Intake (g/fish/day) 1.46a 1.49a 1.44a
Feed Conversion Ratio 1.42a 1.41a1.34b
(-5.6%)
Survival Rate (%) 83.31a 84.92a 90.01a
abc – P<0.05
Intensities of monogenean infection in Pangasius fed different levels of a blend of botanical extracts during 8 weeks.
INTENSITY OF INFECTION
(average number of monogenea per fish)
0
1
2
3
4
5
6
7
8
9
10
0 1 2 3 4 5 6 7 8
WEEKS
MO
NO
GE
NE
A P
ER
FIS
H CONTROL
APEX 0.5 kg/MT
APEX 1 kg/MT
HEAVY
RAIN
a
a
a
a
a aa
a
b
a
b a
b
b
b
b
b
c bc
c
Prevalence of monogenean infection in Pangasius fed different levels of a blend of botanical extracts during 8 weeks
PREVALENCE MONOGENEAN GILL
PARASITES
0
10
20
30
40
50
60
70
80
90
100
CONTROL APEX 0.5 kg/MT APEX 1 kg/MT
% O
F F
ISH
IN
FE
CT
ED
a a
b
Field trials with Gilthead seabream (Sparus aurata) in Greece
Objective: optimize formulation of APEX to reduce infestation
of seabream by monogenean gill parasites
Method: empiric testing in sea cages during 2010-2013 under
veterinary supervision at the farm
Results: application of APEX BRANCHIA may-july (challenging summer
period) resulted in 50-60% reduction of average monogenean
count per fish (light microscopic observation)
Nutriad’s innovative research on prevention of monogenean gill parasites
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Solution
• Reduce monogenean infestation throughout growout phase
• Preventive strategy:
• Starter feeds: 3 kg/ton
• Grower feeds: 2-3 kg/ton
APEX® BRANCHIA C
A synergistic formulation of natural compounds
with anti-parasitic action
•Medium chain fatty acids
•Botanical extracts
•Encapsulated essential oil complex
Conclusion
APEX® BRANCHIA C
• reduce the count of monogenean gill infestations on
productivity
• Preventive strategy:
• Starter feeds: 3 kg/ton
• Grower feeds: 2-3 kg/ton
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