Conditionnement Et Stockage Des Aliment Des Poissions

CONDITIONING AND STORAGE OF FISH FEEDS
Conditioning the feed is an important part of feed processing. When mash feed passes
through the conditioner, it is exposed to high pressure steam. This steam provides the
heat and moisture required for starch gelatinisation, particles adhesion and removal of
pathogens in the mash. The steam temperature and retention time in the conditioner are
two important factors that can influence pellet quality, defined with the so-called pellet
durability index (PDI) and the hardness level of the pellet.
PDI (%) = Quantity of feed that remain as pellets/Total quantity of feed introduced
*100
a) Effect of conditioning on pellet durability and hardness
Previous studies showed that the optimum temperature for producing high quality
pellets is 80°C, and the minimum retention time in the conditioner is 30 seconds. In
conditioners with a high retention time, feed undergoes a three to four minute
conditioning process in order to improve the adhesion characteristics of the pellet. A
higher retention time in the conditioner causes more moisture penetration into the feed
particles, and can be obtained through reducing peddle movement for example. It has
been demonstrated that increasing the retention time of the mash diet in the conditioner
(with a constant temperature) increases the PDI and hardness. Some authors reported
that increasing the retention time (from 5 to 15 seconds) in the conditioner and adjusting
peddles’ angle increased the PDI from 42.2 to 72.2%. Steam temperature can also have
a great effect on pellet quality. It has been shown that steam conditioning feed at 60, 75
and 90°C improved PDI by 490%, 508% and 541% and hardness by 226%, 275% and
433%, respectively compared to dry conditioning. But while increasing temperature in
the conditioner can enhance pellet quality, it can also lead to biochemical reactions
which in turn can decrease nutrients availability and negatively affect the beneficial
effects of pelleting.
b) Effect of conditioning on the microbial load and FCR
Temperature and retention time in conditioning can affect feed production, pellet
quality, and consequently fish performance. The main advantage of feeding pellet to
farm animals is the improvement of growth performance through feed intake, weight
gain and feed conversion ratio (FCR). Fish fed a pellet diet end up with better growth
performance compared to those which receive a mash diet. It has been demonstrated
that weight gain increased and FCR decreased when temperature in the conditioner was
increased. This is attributed to the fact that during conditioning, disulfide bonds are
broken, hence increasing digestibility of nutrients in the intestine. An added effect is
that conditioning at high temperatures (like 82°C) reduced the microbial load
(pathogens) and can therefore improve FCR.
Usually in small fish farms, where local feeds are produced, hot water is added to the
dry feed to form a mash before it is passed through a pelletizer. This is a part of the
conditioning process. As by this process, steam is provided to the starch in the feed for
gelatinization, but further effect of heat and pressure in the pelletizer improves pellet
stability, pathogenic organisms and also anti-nutritional can be factors eliminated.
In a summary, conditioned feed have the following advantages:
- Improved pellet durability index (PDI)
- Improved feed utilization as a result of increased digestibility
- Pathogenic micro-organisms are destroyed
- Improve the weight gain of the fish as the FCR of the feed is improved.
- Reduced anti-nutritional factors
Conditioning of the feed mash can increase the quality of the pellet. The conditioning
process gelatinizes starch in grains and makes crystalline structure of starch available
for enzyme reactions, which lead to better nutrient digestibility. The benefits gained
from conditioning the feed before pelleting is of particular interest to fish since they do
not well pick up dissolved food and the presence of anti-nutritional factors greatly
reduce nutrients digestibility.
FEED QUALITY, FEED STORAGE, AND FEED LOSS MANAGEMENT
Feed quality: In composing feed, it is important that right ingredients are used and be
included in the right proportions. Uniformly mixed rations are important to maximize
intake and performance of feed. Total mixed rations should be precisely balanced for
maximum performance, and the mixing of ingredients should be thorough and
consistent. Performance can also be affected if ration ingredients are of poor quality. In
addition, it is important economically to avoid overfeeding expensive nutrients, or have
the risk of nutrient deficiencies.
Reducing variability of the feed is also important to promote digestive health of the fish.
Rations should be mixed in the same order each time and delivered at a consistent level.
Mixing equipment should be regularly inspected for fluid leaks, appropriately
maintained and cleaned.
In summary, to have feed of good quality, ensure the following are respected:
- Use the right ingredients.

- Grind the ingredients well and mix well to ensure homogeneity.
- Include the right ingredients in their correct proportions.
- Ensure that the ingredients are of good quality.
- Mixing equipment should be regularly inspected for fluid leaks, appropriately
maintained and cleaned them.
FEED STORAGE:
- Feed storage should be done in an environment protected from vector carrying

agents cockroaches and rats.
- The place should be clean and inspected periodically for contamination.
- Chemicals and hazardous material should never be stored in areas where feed is
stored.
- The storage area should be ventilated enough to avoid heat building which can
result to oxidative processes making the feed rancid.
- The feed should not be deposited on bare floor, rather positioned on stands.
- Feed should be stored away from the sun to avoid chemical damages.
- Feed should not be stored for period longer than expected as this will become
stale and consumption will be affected.

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CONDITIONING AND STORAGE OF FISH FEEDS

a) Effect of conditioning on pellet durability and hardness

b) Effect of conditioning on the microbial load and FCR

In a summary, conditioned feed have the following advantages:

- Improved pellet durability index (PDI)

- Improved feed utilization as a result of increased digestibility

- Pathogenic micro-organisms are destroyed

- Reduced anti-nutritional factors

FEED QUALITY, FEED STORAGE, AND FEED LOSS MANAGEMENT

maintained and cleaned.

- Use the right ingredients.

- Feed storage should be done in an environment protected from vector carrying

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