Feed Management

Feed Appearance Feeding response often result good feed! Odor, taste, texture, appearance & size Uneaten feed is worthless! Flavoring is common.

Attractability/Pallatability Shrimp feed by olfaction (smell) Fish are mostly sight feeders Attractants: fish, krill or shrimp-head meal, Artemia, Oils, Betaine These should elicit an immediate response. Two hour water stability. If not consumed by then, forget it (leaching)

Attractability/Palatability Common misconception: stinky feed is good feed! Not always: we don’t smell what they smell palatability: is particle picked-up and then consumed/ingested? Texture/handling ability of pellet important, particularly with shrimp

Pellet Stability In the past, farmers thought the longer the pellet stability, the better the feed.. We now recognize that if a pellet has lost its attractability, it will not likely be eaten Attraction and stability both needed. Binders can be expensive normal stability: around 4-6 hrs determined by: dry matter, immersion, fractures, etc.

More on Appearance Because some aquatics feed by smell, color may be irrelevant. However, color can give you a clue to the nutrient composition of the feed. Shrimp, unlike fish, can remove tiny ingredient particles and discard them

Feed Pellet Size Pellet size correlates with animal age Right size, location, ease of consumption, correct formulation, etc.,… you get the idea! REM: Size from 50 µM-10 mm in dia.

Feed Pellet Size: Shrimp larvae: <50, , 250, 500 µM, according to larval substage postlarvae: flakes, fine crumbles (500 µM) juveniles to 2-3 g: medium crumble (1mm) to coarse crumble (2mm) 3-6 g: short pellet (3/32 x 2-4 mm) 6-10g: medium pellet (3/32 x 6 mm) g: long pellet (3/32 x 10 mm) over 16 g: 1/8 in. diam, various lengths point: one pellet per shrimp per feeding

Always remember… Three important issues: proper-sized pellet, nutritionally-balanced, right place/time Does behavior of aquatics influence feed management? You bet it does!!!! 1) schooling behavior, 2) migratory behavior, 3) nutrient requirements, 4) physiology

Proper Feed Storage Since feeds spoil, storage and shelflife are always of concern. What breaks down? Vitamins, lipids, proteins Fats and oils break down via rancidification Proteins can become deaminated: do not use any feed over 90 days old

Proper Feed Storage Watch out if your are importing!! = delays Delays can turn feed into high- priced fertilizer or make it downright toxic! Feed typically shipped in 50 lb bags sea freight or over-land trucking normal shipment: 40 bags/pallet (one ton at a time) if mill is nearby: shipment is a granel or loose-pelleted…implys a silo and bagging system at the farm

Feed Bags Feed bags are made of many materials: Paper on outside, plastic liner Continuous plastic (no weave, no air holes) Woven polymer Typically contain labels stating feed type, pellet size, proximate analysis, ingredients, date of manufacture, etc. Must be unloaded immediately and placed in proper storage

Proper Feed Storage Feeds should be stored in a dry, cool and well- ventilated area Spoilage will occur immediately if feeds become wet Bags stored on wooden pallets No more than 5 bags high between pallets:air circ. Also, no sunlight!

Proper Feed Storage Surfaces are often cooler than the bag: moisture migration Feed moisture (~8-12%) will migrate to the cool area, accumulate This encourages growth of molds (REM: Aspergillus flavius, aflatoxin??)

Proper Feed Storage Direct sunlight will destroy vitamins/lipids in feeds Feeds should be purchased, delivered, and utilized on a monthly basis (2-3 containers per month for large farms) Economic loss of feeding deficient feed may be greater than cost associated with discarding it!

Feeding of Fish/Shrimp The main issues regarding the feeding of fish/shrimp are the following: 1) growth rate (GR) 2) feed rate (FR) 3) pellet size 4) feed frequency 5) feed management

Growth of Penaeid Shrimp GR of penaeid shrimp is high, esp. juveniles following stocking In some cases, it can exceed 1000% per wk Growth curves describing weight gain of shrimp are developed in terms of percent weight gain per day, or over any period of time GR varies throughout life cycle

Growth of Penaeid Shrimp Growth of young shrimp is typically logarithmic or exponential until g Afterwards, it normally becomes linear REM: just because weight is increasing, does not mean biomass is increasing Many times growth will be slow and then increase, sometimes stop Must be confirmed by biomass/population sampling

Growth of Penaeid Shrimp When viewing growth curves, it is important to note that they seldom appear as in the classical representations They appear more like jagged lines reflecting sudden increases/decreases in mean body weight Attributed to molt status (or sampling error) In the first two days post-molt, shrimp can gain g in weight

General Feeding Guidelines The smaller the fish/shrimp, the higher the percentage body weight fed as feed/day PL’s (less than 0.5 g) are fed up to 50% of their body weight per day, some fish will eat their body weight per day!) The percentage decreases with weight of fish/shrimp As stocking density increases, most farmers increase overall feeding rate for entire production cycle

Specific Feeding Guidelines Note: this is just an example, can vary with stocking density

Estimation of Feed Usage in Shrimp Ponds

Feeding of Penaeid Shrimp The actual feeding guideline assumes a specific growth rate according to season, species of shrimp L. vannamei: dry season 0.5 g/wk, wet season 1.5 g/wk L. stylirostris: dry season 1.5 g/wk, wet season 1.5 g/wk (poor survival) has a targeted weight of shrimp to be harvested based on experience, investment requirements and market price must play around with it Can it be followed? Not usually.

Feed Management It is very difficult and often impractical to follow a feeding guideline (overfeeding) often not advisable only used as a general range for weight fine tuning/management comes from estimation of feed consumption/biometry this is undertaken through use of feeding trays and population sampling

Pond Biomass Sampling Determines overall population of shrimp in ponds uses cast nets cast net size: 8-10 ft diameter (3 m) mesh size: 1/8 in. (0-5 g), 1/4 in. (5+g) pond matrix developed, sampled as an “X” sampled at night (even distribution), new moon at least 20 casts population = (count/cast net area/spread coefficient) x total pond area

Feeding Trays Developed back in the 80’s as a spin-off of the intensification of shrimp farming in Taiwan overfeeding was causing problems with pond water quality originally placed a portion of feed on tray and estimated “appetite”/consumption by refused portion after a period of time now-a-days used to feed entire pond

Feeding Trays Method 1: if you are just evaluating consumption, use a small number of trays, evenly distributed throughout the pond semi-intensive: 2/ha, intensive: 6/ha trays are cm diameter, ring weighted, use about 2 mm mesh on bottom add 150 g feed, read refused portion after 2 hrs estimate as a percentage of total, record as a simple number (0,1,2,3) and compare to a chart recommending modifications

Feeding Tray Guideline No residual feed = 0 = 50% increase 0-10% residual = 1 = 25% increase 10-25% residual = 2 = 10% increase 25-50% residual = 3 = no change 50-75% residual = 4 = decrease 25% % residual = 5 = no feed issue: workers must be trained to observe residual, must correlate dry feed weight to wet feed volume in samplers

Peruvian-style Feeding Trays By this method, all feed applied to trays trays are large, 3m x 3m, 10 trays/ha advantage: very accurate consumption information advantage: all waste accumulates near tray advantage: FCR will drop % disadvantage: 100 trays/10 ha pond; 3,000 trays per farm, 100 trays/worker/day issue: Is this cost effective?

Feeding Schedule Shrimp are most active and well-distributed at night daytime = poor distribution, less activity feeding times: 05:00 (25%), 19:00 (25%), 0:00 (50%) pay very close attention to where shrimp are at these times and whether molting feeding times often have to be adjusted to allow for only one group of feeders

Feeding Frequency 2x day until 4-5 g, then 3x day Frequent feedings better = better WG More feeding = more labor cost (not practical for most farms) Also causes problems in terms of pellet distribution…randomization important.

Feed Distribution Distribution of feed to shrimp is just as important as nutrition and amount poor distribution means poor growth, wasted energy on part of the shrimp, economic loss to farm must understand migratory behavior and physiological response must feed where the shrimp are each pond different time of day, entrance of water into pond, turbidity, etc. are all important

Feed Distribution In other words, study the pond know where to put the feed usually broadcast by hand from boats in a zig-zag pattern also distributed by blowers on trailer, if ponds small enough, wind OK blowers: 4,000 lb capacity, 45 ft throw equipped with balances for proper dosage, programmable hoppers w/scales

Other Means of Feed Distribution