L10 - L12

• Shrimps are commonly farmed aquaculture species
• Different feed requirements exist at different stages of the shrimp aquaculture cycle
• Various factors affect the feeding regime
• Feed management is important as it can affect water quality, cost, production, etc.
• Feed management differs in various parts of the world
• Shrimps are scavenging, opportunistic feeders
• Shrimps are capable of utilizing suspended food particles in the water column and food organisms living on the pond bottom
• Shrimps reply primarily on chemical attraction and stimulation to locate and consume food, including artificial feeds
• Artificial feeds for shrimps generally have to remain immersed in water for prolonged periods
• Shrimps are benthic feeders, so artificial feeds should be of the sinking type
• Shrimps obtain nourishment from within themselves (yolk sac)
• Shrimps are most active and well-distributed at night, less active during the daytime
• Feeding schedules may vary based on species; for instance, L. vannamei is fed more in the morning and late afternoon, while P. monodon is fed more at night
• Factors affecting feed consumption include species aggressiveness, age and size, availability of natural food, water quality, moulting, and quality of commercial feed
• Feed management of L. vannamei in Vietnam is regulated by the government, but many farmers still use P. monodon feeds
• Feeding practices for L. vannamei in Vietnam include broadcast feeding from a boat or raft, or directly within the pond, using feeding trays to monitor feed consumption and make necessary ration adjustments
• Learning objectives:

  • Describe the types of feeds required by shrimps at each life stage
  • Describe the factors influencing acceptance and consumption of feeds
  • Relate factors such as species, age, size, availability of natural food, water quality, moulting, and quality of commercial feed to shrimp feeding behavior
  • Describe the use of feed devices and their applications
  • Discuss the use of feeding tables
  • Calculate the feed requirements given a feeding table
• Aquaculture: Farming Aquatic Animals and Plants by John S. Lucas, Paul C. Southgate
• Juvenile P. monodon are fairly carnivorous, feeding on seaweed, algae, crustaceans, detritus, molluscs, and fish parts
• Adult P. monodon feed on crustaceans, annelids, algae, and mud
• Life stages and food for P. monodon:

  • Nauplius: Non-feeding due to lack of developed mouth and alimentary canal
  • Zoeae to mysis: Phytoplankton and small zooplankton like rotifers
  • Post larva: Zooplankton and small crustaceans
  • Juvenile: Small crabs, shrimps, molluscs, polychaetes, fish debris, sand, silt
  • Adults/Juveniles: Algae, seaweed, crustaceans, detritus, molluscs, and fish parts
• Farmed shrimps are scavenging, opportunistic feeders in their natural environment and can consume phytoplankton, zooplankton, and microbial flocs
• Farmed shrimp rely primarily on chemical attraction to locate and consume their food, including artificial feed
• Feeding practice at the hatchery stage in shrimp aquaculture:

  • Optimization of feeding regimes for good water quality, fast growth, and high survival of larvae
  • Consideration of all sources of live, fresh, or frozen food with attention to pathogen risk
  • Supplementation of live diets with artificial dry or liquid diets
  • Dose rates for artificial diets based on observations of larval feeding habits and water quality
  • Frequent supervision and monitoring to avoid overfeeding artificial diets
• Younger shrimp need more feed than adults because when smaller, they need more nutrients to digest as their digestive tract is not fully developed
• Importance of pellet hydrostability:

  • Pellets must maintain their physical integrity long enough for animals to detect and consume them
  • Poor hydrostability leads to wasted feed, increased organic loading of ponds, and reduced profitability
• Characteristics of aquatic animal feeds:

  • Water stability, composition, density, and supplementation are key physical characteristics
  • Feed samples are agitated in Erlenmeyer flask shaker to simulate water effects on feed pellets
  • Higher percentages indicate higher feed water stability
  • Amount of dry matter loss varies based on feed formula, with feeds lower in protein and higher in starch having higher water stability values
• Factors to consider when formulating practical fish diets:

  • Crude protein level
  • Energy level (expressed as metabolizable energy or digestible energy)
  • Specific amino acid levels
  • Crude fibre level
  • Ash level
• Formulation of feeds varies based on the life cycle stages of fishes, as different stages have distinct nutritional requirements
• Ingredients such as fishmeal exhibit seasonal variations in composition, influencing the formulation of feeds
• Proximate composition of fish meals undergoes changes during the spawning season:

  • Lipid levels increase before spawning and decrease after spawning
  • Variations in lipid content affect the percentages of protein, ash, and carbohydrates in fish meal, showing seasonal changes
• Every feedstock included in a diet formulation serves a specific purpose, such as being an energy source or rich in essential amino acids
• Cost of feed formulation should be considered to interchange feedstocks for cost-effectiveness
• Binders play a crucial role in achieving the required water stability in feeds:

  • Common binders include urea formaldehyde, wheat gluten, and gelatin
  • Gelatin and gluten are highly digestible and contain protein
  • Urea formaldehyde is not permitted in feeds in the European Union (EU) and the United States of America (USA)
  • Starch gelatinization of ingredients like wheat is necessary
• Factors influencing acceptance/consumption of feeds:

  • Flavour: Animal extracts may increase feed consumption and palatability of aquaculture feeds
  • Colour: Chemicals are included to impart a sense of motion due to light refraction
  • Odour: Amino acids naturally emanating from live food organisms enhance feeding response
  • Texture: Presence of spiny appendages may affect feed acceptance
  • Water stability: Feed particles must maintain integrity in aqueous suspension
  • Feeding behaviour: Different species have specific feeding adaptations
• Compounds that increase acceptance of feed:

  • Nucleic acid-related compounds
  • Lipids
  • Nitrogenous base
  • Sulfur-containing organic compounds
  • A mixture of free amino acids is more effective than individual amino acids in phagostimulation
• Use of chemoattractants in formulated feeds:

  • Enhance feed intake and growth
  • Important during weaning onto pellet feed, increasing survival and shortening production intervals
  • Help offset reduction in feed intake during times of disease or stress
  • Encourage the use of bland ingredients in feed that would normally go unused
• Solving the problem of poor or no binders in feeds for shrimps:

  • Use a good binder such as starch gelatinization
  • Ensure a balanced formulation of nutrients and energy level for shrimps/fishes
  • Assessment of water stability for prepared feeds is necessary
• Recall the parameters for determining pellet quality in aquaculture feed

  Describe the use of common binders in aquatic feeds to increase water stability

  Measure the moisture content and water stability of the feed

  Measure weight and total body length of shrimps

  Calculate feeding rations based on feeding tables

  Perform water durability test for created pellet in the lab

  Describe tests used to determine pellet quality

  Measure weight and total body length of shrimps

  Measure out feed rations for shrimps according to feeding tables
• Importance of hydrostability in feeds:

  • Pellets must maintain their physical integrity for animals to detect and consume them
  • Poor hydrostability leads to wasted feed, increased organic loading, higher feed conversions, and reduced profitability
  • Higher water stability percentage means less likelihood of feed disintegration in water