1. Least-cost formulation and feed production

2. Computer Formulation of Feeds
Least-cost feed formulation: a feed formula that is both nutritionally-complete (within limits) and with a minimum ingredient cost (within limits)
now-a-days is developed and completed through the use of computers using linear-programming software
typical packages: Brill, Mix-it
used by most feed mills/manufacturers

3. Least-cost Formulation
Least-cost feed formulations require that the following information be provided:
cost of feed ingredients
nutrient content of feed ingredients
nutritient requirement of the animal
availability of the nutrient to the animal
minimum-maximum restrictions on levels

4. Least-cost Formulations
Costs of feed ingredients and nutrient content are fairly available for most commercial feedstuffs
costs can be evaluated on a daily basis
nutrient requirements are fairly well known
the most critical piece of information regards digestibility/availability of nutrients within the feed ingredient
various indices: DE, ME, APD, etc.
these can be set in formula w/restrictions

5. Least-cost Formulation
these are nutrient and ingredient restrictions that have been used for least cost formulation of catfish feeds
theoretically, protein level does not have to be restricted if essential amino acid requirements are well-known
for catfish, if the minimum requirements for lysine and the sulfur-containing AA’s are met, other EAA requirements are also met

6. Least-cost Formulations
Other restrictions: minimum available phosphorus and digestible energy
only maximum calcium is typically considered due to availability in water
whole fish or other animal protein sources have been shown beneficial for catfish feeds
cottonseed meal is restricted to 10% due to gossypol (protein) content (toxic)
xanthophyll content often restricted due to it causing yellow discoloration of fish at high concentrations

7. Least-cost Restrictions for Shrimp Feeds

8. Least-cost Formulations: other restrictions
Limitations to computer formulations exist and should be recognized
where the computer says its ok, the experienced formulator knows differently
example: too high fat content for pelleting
example: sorghum might be as good as corn in an extruder, but not a pelletizer
this is why advantages are maximized when a number of options are available

9. Computer Formulation of Feeds
Originally, the development of feed formulations was a real task
mathematical models for formulating nutritionally-adequate diets at lowest cost were available
however, everything had to be hand calculated
feed formulation: the preparation of nutritionally-complete diets for feeding animals

10. Least-cost Formulations: other restrictions
In many cases, logistics of obtaining ingredients and their storage limit the number of ingredients
availability of feedstuffs is not as important as having the option to substitute
must also take into consideration the physical, palatability, and toxicological properties of the feed
nutrient availability also varies

11. Least-cost Formulations: restrictions
As mentioned, most least-cost formulae are derived by linear programming
it has its disadvantage in that it uses data out of the NRC handbook for fixed, maximum growth rates
it does not take into consideration optimum return on growth for various feed nutrient concentrations
this requires regression analysis
regression analysis is now being integrated into poultry formulae, probably not yet available for fish

12. Largely provided by Wenger, Inc. and Akiyama
Part 2: Feed Production
Largely provided by Wenger, Inc. and Akiyama

13. Feed Production Two major methods: pelletizing and extrusion
steam pelleting produces a dense pellet that sinks rapidly in water
extrusion produces a low density feed particle that has a tendency to float
steam pelleting uses moisture, heat and pressure to agglomerate ingredients into larger, homogenous particles
steam added to the ground feed mash (mix) partially gelatinizes starch, binding ingredients

14. Pelletizing Feeds
Generally, steam is also added prior to passing the mash through the pellet die
this increases its moisture content to 15-18%
temperature goes up to about 85oC
steam pelleted feeds must be firmly bonded for satisfactory stability in water
starch is important for adequate binding
fat and fiber are antagonistic to process
supplemental fat not added if pelleting

15. Pelletizing Feeds
All conventional pellet mills include the following equipment:
variable speed feeder
conditioning chamber
die and roller assembly
speed reduction device
prime mover
base
the variable speed feeder provides a continuous, controlled flow of feed mix

16. Pelletizing Feeds: conditioning
The conditioning chamber is actually a mixer with either fixed or movable paddles
conditioning is accomplished by the addition of controlled amounts of steam
steam liberates natural oils, partially gelatinizes starches, increases temp, increases moisture
starch gelatinization: loss of birefringence or the irreversible rupture of the native secondary bonds in the crystalline region of the starch granule
the speed reduction device is added to reduce motor speeds to that of the die head
this is absolutely critical for the production of consistent-sized particles

17. Pre-conditioning
gelatinization process
machine

18. Sinking vs. Floating Feeds

19. Typical Pellet Mill

20. Typical Pellet Mill Process Flow

21. Typical Pellet Mill

22. Die Assembly

23. Comparison: extrusion vs. pelleting
Process flow diagrams

24. Typical Extruder (side view)

25. Comparison: pelletized vs. extruded feeds

26. Pellet Comparison: continued

27. Price Comparison

28. 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

29. 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

30. 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!!

31. 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.

32. 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

33. Pellet Appearance Feed pellets should contain no fractures
fractures are indicative of poor processing and conducive to poor water stability
fractures allow water to seep into pellet more rapidly, pellet hydrates, breaks
feed pellets should not clump together (indivative of poor drying, results in poor nutritional quality, stability)
“fines” from bags should total less than 2%
result: you lose money, get poor water quality

34. 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

35. 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)
10-16 g: long pellet (3/32 x 10 mm)
over 16 g: 1/8 in. diam, various lengths
point: one pellet per shrimp per feeding

36. Feed Pellet Size
For a 2mm x 6mm pellet, you have approximately 1 million pellets per 100 lb bag
if your 10 ha pond has 2 million shrimp in it (20 per sqm), feeding two 100 lb bags gives each shrimp 1 pellet/feeding
20 pellets per sqm pellet density