Feed Conversion Ratio (FCR) is a critical performance metric in prawn (shrimp) farming, measuring the efficiency with which feed is converted into body mass. A lower FCR indicates better efficiency, meaning less feed is required to produce a kilogram of prawns, leading to reduced costs and higher profitability.
In prawn farming, feed accounts for up to 60-70% of total production costs, making FCR optimization essential for economic sustainability. Factors influencing FCR include feed quality, feeding strategies, water quality, stocking density, and farm management practices.
This guide explores practical strategies to improve FCR in prawn farming, ensuring better growth rates, reduced waste, and higher profits.
Table of Contents
1. Understanding Feed Conversion Ratio (FCR)
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- Ideal FCR in prawn farming: 1.2 – 1.8 (varies by species and farming system).
- Higher FCR (>2.0) indicates inefficiency, leading to wasted feed and increased costs.
Why Improve FCR?
- Reduces feed costs (major expense in prawn farming).
- Minimizes waste and pollution (uneaten feed degrades water quality).
- Enhances growth rates and survival.
- Increases profitability by optimizing resource use.
2. Key Strategies to Improve FCR in Prawn Farming
A. Optimize Feed Quality
Feed quality is the most significant factor affecting FCR. Poor-quality feed leads to poor digestion, slow growth, and higher waste.
1. Use High-Protein, Balanced Feed
- Prawns require 25-35% protein (varies by species and growth stage).
- High-quality ingredients (fishmeal, soybean meal, squid meal) improve digestibility.
- Avoid low-cost, filler-heavy feeds that reduce nutrient absorption.
2. Ensure Proper Pellet Stability
- Water-stable pellets prevent rapid disintegration, reducing nutrient loss.
- Sinking vs. Floating pellets: Choose based on prawn feeding behavior.
3. Add Digestibility Enhancers
- Enzymes (phytase, protease) improve nutrient absorption.
- Prebiotics & probiotics enhance gut health and feed utilization.
- Lecithin and phospholipids improve fat digestion.
B. Improve Feeding Management
Improper feeding leads to overfeeding (waste) or underfeeding (stunted growth).
1. Feed in Small, Frequent Portions
- 4-6 meals per day (automated feeders improve consistency).
- Avoid large, infrequent meals that lead to waste.
2. Adjust Feeding Based on Prawn Behavior
- Check feeding trays after 1-2 hours:
- If empty, increase feed slightly.
- If leftover feed, reduce quantity.
- Night feeding: Prawns are more active at night; adjust schedules accordingly.
3. Avoid Overfeeding
- Overfeeding increases FCR and pollutes water.
- Follow feeding charts based on prawn size and biomass.
C. Maintain Optimal Water Quality
Poor water quality stresses prawns, reducing feed intake and growth.
1. Monitor Dissolved Oxygen (DO)
- Ideal DO: >5 mg/L (below 3 mg/L reduces feeding activity).
- Use aeration systems (paddlewheels, diffusers) to maintain oxygen.
2. Control Ammonia & Nitrite Levels
- Ammonia (<0.1 mg/L), Nitrite (<0.2 mg/L) – High levels are toxic.
- Biofilters and water exchange help manage nitrogenous waste.
3. Maintain Proper Temperature & Salinity
- Optimal temperature: 28-32°C (outside this range, metabolism slows).
- Salinity: 10-25 ppt (adjust for species-specific needs).
4. Regular Water Exchange & Sediment Removal
- Remove sludge (accumulated waste) to prevent toxic gas buildup.
- Exchange 10-30% of water weekly to maintain quality.
D. Optimize Stocking Density
Overcrowding increases competition for feed and oxygen, raising FCR.
1. Follow Recommended Stocking Rates
- Extensive systems: 5-15 prawns/m².
- Semi-intensive: 15-30 prawns/m².
- Intensive: 30-60 prawns/m² (requires strong aeration).
2. Grade & Separate Prawns by Size
- Size variation leads to dominance (bigger prawns eat more).
- Regular grading ensures uniform growth and better FCR.
E. Enhance Pond Bottom Management
Uneaten feed and waste accumulate at the pond bottom, degrading water quality.
1. Use Substrate or Liners
- Concrete or HDPE-lined ponds reduce sediment buildup.
- Sandy or clay bottoms should be cleaned regularly.
2. Implement Probiotic & Microbial Treatments
- Bacillus spp. break down organic waste, improving water quality.
- Biofloc systems recycle nutrients, reducing feed waste.
F. Implement Health Management Practices
Diseases and stress reduce feed efficiency.
1. Prevent Disease Outbreaks
- Use disease-free postlarvae (PL) from certified hatcheries.
- Apply immunostimulants (β-glucans, vitamins) to boost immunity.
2. Reduce Stress Factors
- Avoid sudden changes in water parameters.
- Handle prawns carefully during sampling and harvesting.
G. Use Advanced Farming Technologies
Modern techniques can significantly improve FCR.
1. Automated Feeding Systems
- Precision feeders reduce overfeeding and waste.
- Sensors adjust feeding based on prawn activity.
2. Biofloc Technology (BFT)
- Microbial protein recycles waste, improving FCR.
- Reduces water exchange needs, maintaining stable conditions.
3. Recirculating Aquaculture Systems (RAS)
- Controlled environment optimizes growth and feed efficiency.
- Higher initial cost but better long-term FCR.
3. Monitoring & Record-Keeping
Tracking performance helps identify inefficiencies.
Key Metrics to Monitor
- Daily feed intake
- Growth rate (weekly sampling)
- Water quality parameters (DO, pH, ammonia, temperature)
- Survival rate
Adjust Strategies Based on Data
- If FCR increases, check feed quality, water quality, or disease issues.
- Compare batches to identify best practices.
Here are ten frequently asked questions (FAQs) about prawns:
1. What is the difference between prawns and shrimp?
Prawns and shrimp are different crustaceans. Prawns have three pairs of claw-like legs, while shrimp have two. Prawns also have branching gills and a straighter body compared to shrimp.
2. Are prawns healthy to eat?
Yes, prawns are a good source of protein, low in fat, and rich in omega-3 fatty acids, vitamins (B12, E), and minerals (selenium, zinc). However, they contain cholesterol, so moderation is advised for some diets.
3. How can I tell if prawns are fresh?
Fresh prawns should have a firm texture, a mild ocean-like smell (not fishy), and a translucent appearance. Avoid prawns with black spots, a slimy texture, or a strong ammonia odor.
4. How should I store fresh prawns?
Keep fresh prawns in the coldest part of the fridge (0–4°C) and use them within 1–2 days. For longer storage, freeze them in an airtight container for up to 3 months.
5. Can you eat prawns raw?
Raw prawns can carry parasites or bacteria, so it’s safer to cook them thoroughly. If consuming raw (e.g., in sushi), ensure they are sashimi-grade and properly frozen to kill pathogens.
6. How do you peel and devein prawns?
- Remove the head (if attached).
- Peel off the shell, leaving the tail if desired.
- Make a shallow cut along the back and remove the dark digestive tract (vein) with a knife or toothpick.
7. What’s the best way to cook prawns?
Prawns cook quickly (2–3 minutes per side) and can be grilled, boiled, fried, or sautéed. Overcooking makes them rubbery—they’re done when they turn opaque and pink.
8. Why do prawns turn pink when cooked?
The color change is due to a protein called astaxanthin, which is naturally present in prawns but bound to other molecules. Heat releases astaxanthin, turning the prawns pink.
9. Are prawns safe for people with shellfish allergies?
No. Prawns are shellfish, and people with shellfish allergies should avoid them as they can trigger severe allergic reactions.
10. Are farmed or wild-caught prawns better?
- Wild prawns are often considered tastier but may have sustainability concerns.
- Farmed prawns can be more eco-friendly if responsibly sourced (look for certifications like ASC or MSC), but some farms use antibiotics or harm mangroves.