Feed Management MARI-5314 Dr. Joe Fox

Feed Appearance Feeding behavior of aquatic animals is usually associated with some quality of the feed: odor, palatability, texture, appearance, size bottom line: a nutritionally- balanced feed is of little value if not consumed often, the animal must be “attracted” to the particle example: shrimp feeds w/attractants leached attractants are detected through chemoreceptors located throughout their body

Attractability/Pallatability Shrimp, unlike fish, feed by olfaction, not by sight fish cue on color, appearance, movement, all vision-related attractants: fish meal, fish oils, krill meal, shrimp head meal, Artemia meal feeds with added attractability should bring the target animal immediately to the pellet without binders, attractants leach out in 2 hr if not consumed by then, forget it

Attractability/Palatability Common misconception: if farmer can smell attractant, the feed is good again, we don’t smell what they smell palatability: is particle picked-up and then consumed/ingested? Regards texture and handling ability of pellet shrimp need this more than fish because they are sloppy eaters!!

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 the key is to provide the right combination of attraction and stability accomplished via binders, but expensive normal stability: around 4-6 hrs determined by: dry matter, immersion, fractures, etc.

More on Appearance Because some aquatics feed by smell, color is often irrelevant (REM??) however, color can give you an idea of the nutrient composition and manufacturing quality of the pellet pellet color should be uniform, few large ingredient particles shrimp, unlike fish, can remove tiny ingredient particles and discard them

Feed Pellet Size What feed pellet size you feed is determined by age of animal size of particle must be the one most efficient for location and consumption by animal proper nutrient package, right size, well- distributed smaller pellets usually imply easier distribution feed particles range in size from less than 50 µM to over 1/8 in. diameter

Feed Pellet Size 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

General Comments Now that you have an idea of how feeds are formulated and produced, we will discuss feed storage, management and application three important issues: proper-sized pellet, nutritionally-balanced, right place/time how this is accomplished depends on: 1) schooling behavior, 2) migratory behavior, 3) nutrient requirements, 4) physiology

Proper Feed Storage Because feeds contain ingredients that are susceptible to degradation, you are concerned with storage conditions and shelf life What breaks down? Vitamins, lipids, proteins fats and oils break down via rancidification proteins can become deaminated: do not use any feed over 3 months old big problem for those who import feed

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 100 lb bags sea freight or over-land trucking normal shipment: 450 x 100 lb bags in one 40 ft container if mill is nearby: shipment is a granel or loose-pelleted a granel would imply that the farm has a silo and bagging system

Proper Feed Storage 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: temperature needs to be consistent bags stored on wooden pallets, not on floor no more than 5 bags high between pallets allows for adequate air circulation between bags, constant or similar moisture, temp

Proper Feed Storage Do not store bags directly on concrete floors or touching walls of building surfaces are often cooler than the bag: moisture migration feed moisture (around 8-12%) will migrate to the cool area, accumulate this encourages growth of molds (REM: Aspergillus flavius, aflatoxin??) also avoid direct sunlight: diurnal temperature flux

Proper Feed Storage Direct sunlight will adversely affect the vitamin and lipid quality of the feed do not store feed more than 3 months post manufacture feeds should be purchased, delivered, and utilized on a monthly basis (2-3 containers per month for large farms) spoiled, wet or old feeds cannot be used economic loss of feeding deficient feed may be greater than cost associated with discarding it

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

Growth of Penaeid Shrimp Growth of penaeid shrimp is quite fast, especially during the juvenile phase, right after 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 growth rate 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 shrimp, the higher the percentage body weight fed as feed/day juveniles (less than 0.5 g) are fed up to 50% of their body weight per day the percentage decreases with weight of 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 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 (no other method available) 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 (can be determined by CV) 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 Most farms feed only twice per day until 4-5 g, three times per day afterwards nutrition available in feed is enhanced by more frequent feedings translates into better weight gain also implies more cost in effort, not practical for most farms also causes problems in terms of pellet distribution

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