- Aquafeeds should be manufactured according to a formula recommended by
a competent nutritionist and should be specific for the aquatic target species
being fed and intended farm production system (Csengeri & Tacon, 2000;
Tacon, 1996).
- While most temperate freshwater diets may be largely based upon the use
of plant protein and energy sources, and cold water marine diets are largely
based upon the use of fishmeal and other fishery by-products, there can be
regional differences which reflect optimal use of locally available and/or
least-cost formulation of ingredients (Lazo & Davis, 2000; Li, Robinson
& Hardy, 2000).
- In most existing feed mills the coarse grains and possibly other ingredients
will be ground in a hammer mill, roller mill or otherwise prepared by appropriate
means to allow uniform mixing of the ingredients to formula specifications
and further processing by pellet mill or extrusion to the cooled and finished
product. The feed, properly cooled and dried after processing, is then ready
for sacking or bulk delivery to the farm.
- The particle size(s) of the ingredients may be limited by the type of process
equipment available in an old mill. In aquaculture feeds particle sizes are
typically smaller, some as small as 50 microns to allow proper mixing, pelleting
or extrusion of the feed (Erickson, 2000; Halvorsen, 2000).
- An important factor is the conditioning and cooking process of the mash,
whether it is to be pelleted or extruded (or a system which employs the principles
of both), the starch must gelatinize so that the feed is digestible and maintains
its integrity in water. This will assure that the feed nutrients are consumed
by the animal and do not end up as fertilizer or potential pollutant within
the intended farm production system (Bartone, 1999).
- Generally, pelleting is less expensive than extrusion and may be cost-effective
depending upon a variety of factors including the type and behavior of the
species being cultured, types of ingredients available, and resources of the
feed miller.
- Newer hybrid machines which combine the best attributes of both pellet
mills and extruders may be an exciting development for aquaculture. For specific
details on the different types of manufacturing processes which may be employed
for the production of animal feeds, including aquaculture feeds, readers should
consult Akiyama and Tan (1991), Barber (2000), Barrows (2000), Barrows &
Hardy (2000), Best (1999), Gill (2000b), Kearns (1998), McEllhiney (1994),
Pipa & Frank (1989), Riaz (2001), Rout & Bandyopadhyay (1999), Sunderland
(2001), Tan & Dominy (1997), Tsang (2001) and Woodroofe (1999).
For aquafeeds prepared from manufacturer’s
formulas:
- Formulations should be determined by the manufacturer’s resident nutritionist,
based upon the known dietary nutrient requirements of the animal and farming
system for which the feed is being formulated, prior practice, or research
findings.
- The mill should use reasonable and accurate nutrient specifications for
each ingredient.
- Since the dietary nutrient requirements of farmed aquatic species are still
being defined, it is important for the feed miller/nutritionist to stay abreast
of current research knowledge and findings.
- Use of drugs and other ingredients should follow ingredient label directions
and regulatory requirements. (The supplier’s label should be followed.
Do not use a product for which there is no label; consult management for guidance.)
- All medicinal feed additions (drugs) should be stored separately from all
other feed materials, products and premixes. Access to the drug storage area
should be limited to authorized personnel only (UKASTA, 1998, 2000).
- The production manager should be responsible for the plant having a complete
set of current formulas for the aquatic species to be fed.
- All formulas must indicate: the formula identification (number), feed name
(type and species), effective date, weight/percent each ingredient, and drug/medication
(if used).
- Obsolete formulas should be filed at the feed mill for at least one year
after last use.
For aquafeeds prepared by the customer’s formulas
(custom feeds):
- Before a customer formula feed can be manufactured, there should be approval
from the general manager. Custom formulas are those orders which deviate from
a standard production formula and are specifically requested by a customer.
- The basis for approving a custom order may be as follows: that there is
no alternate feed in the program that will do the job, that the plant is physically
capable of producing the feed and the feed ingredients will not compromise
the quality of other feeds manufactured in this mill, and that it must be
legal (check with a government feed control official).
- Each and every customer request should be reviewed for approval. Blanket
approvals should not be allowed.
- Typically, a consent is obtained from the customer that will essentially
release the manufacturer from liability for impaired animal performance.
- Mixing and batching aquaculture formulations: the batch operator should
receive proper training for the task of mixing and should have an understanding
and working knowledge of ingredients, premix, drug, and concentrate labelling,
equipment function, ingredient and product flow, weights and measures, and
equipment maintenance.
- Maintenance of production records: production records should include the
following information: date mixed, type of feed mixed, formula and lot number,
actual yield, mixing personnel, bin assignment, drug inclusions, and sequencing
and flushing.
- Production runs of medicated feeds should be grouped together as much as
possible. When sequencing (grouping) is not possible, flush the mill mixing
system with an adequate amount of ground corn meal, or similar major ingredient.
Flush material should be routed back into the same batches of similar medications.
- All liquid application systems should be check-weighed quarterly for accuracy
by the production manager or representative. Mixing times for all feeds should
be posted.
- Batch scales should be check-weighed for accuracy on a regular basis and
inspected annually by an authorised scale inspection company (or qualified
government entity).
