dr. a.p sharma lect2nd

8/7/2019 dr. a.p sharma lect2nd

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Role of Nutrition in Fish Seed

Production

A. P. SharmaDean

College of Fisheries

G.B. Pant University of Agriculture &Technology, Pantnagar


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Food requirement of fishes

Energy is needed for the maintenance of all

living organisms

Most plants obtain their energy directly from the

sun and use that energy to synthesize the

complex molecules which make the structural

and storage parts of the plant

Animals get their energy from oxidation of complex molecules which are eaten by the

animals


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Food requirement of fishes

The energy in feed is not available untilthe complex molecules are broken downto simpler molecules by digestion

The ability to digest feed by different fishspecies is different

The food requirements of different species

vary greatly Energy is stored in the chemical structure

of the complex molecules of feed materials


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Energy requirement Feed provide maintenance energy first

then the remaining energy is used for increasing growth

The requirement of energy of fishes is lessthan birds and cattle

When feed has excess amount of energy,the fishes stop feeding (excess amount of

energy reduces feed consumption) Theexcess amount of energy leads to fatdeposition and reduce the dress out


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Nutrient requirement of fishes

There are two aspects for this

What is the energy content and what is the

protein content of feed In general, if the protein requirement is full

filled, the energy requirement already be

full filled

It means energy protein ratio is important

Highly proteinacious diet is also harmful


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Nutrient requirement of fishes

8- 9: 1 :: energy : protein ratio is found

satisfactory for carps (max. growth is

obtained at 8.7- 9.1: 1) If the feed has 32% protein formed with

50% soybean meal, 40% grains, 8%

animal products and 2% vitamins and

minerals. This contain 2.8 k cal digestibleenergy/ g of dry feed of this


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Feeding strategies

Determine how much should be fed

(Ration size)

Determining how many times the organismshould be fed in the day and optimum time

of feeding

Efficiently broadcasting the predetermined

ration to the system


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Feeding strategies (Ration size) An optimum ration is one which gives the best

growth and FCR (Results in minimum wastageand minimum deterioration of the water quality

Ration size is variable (A juvenile fish requiresmore energy per unit weight for metabolism and

has potential to grow faster than an adult fishand need higher ration)

Water temp. also affects feeding rate

Ration size is calculated as a percentage of thebiomass present

Ideally feeding rate should be adjustable daily

Daily feed requirement Body weight to be fed daily (%)= FCRx3xAX100

B


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Feeding frequency

Important to ensure maximal FCR and dress weight ofthe cultured organism

For optimum growth and feed conversion, each feedshould ideally be 1% of the body weight

Survival is not significantly influenced by feedingfrequency once the transition from an endogenous to anexogenous food supply is complete.

Higher feeding frequencies reduce starvation andstunting, thereby resulting in uniformity in size

Dry feed need to be distributed more frequently thanmoist

At least 90% of the presented feed should be consumedwithin the first 15 minutes of the feeding time


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Feeding frequency

Important to ensure maximal FCR and dress weight ofthe cultured organism

For optimum growth and feed conversion, each feedshould ideally be 1% of the body weight

Survival is not significantly influenced by feedingfrequency once the transition from an endogenous to anexogenous food supply is complete.

Higher feeding frequencies reduce starvation andstunting, thereby resulting in uniformity in size

Dry feed need to be distributed more frequently thanmoist

At least 90% of the presented feed should be consumedwithin the first 15 minutes of the feeding time


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Feeding Rate

Fish Weight (g) Feeding rate (%) Feeding frequency

(time/day)25 4.5 3

50 4.0 3

75 3.6 3

100 3.3 3

150 3.1 2

200 3.0 2

250 2.6 2

300 2.4 2

400 2.1 2

500 1.7 2

600 1.4 2


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Feed ingredients

Carotenoid supplements- Xanthophylls

and carotenoids are the most important

classes of pigments for fish and

crustaceans. Canthaxanthin and

astaxanthin add colour to the flesh and

eggs


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Type of feed

Starter feed Larger than 400 , good growth can be obtained, must be

readily consumed by fish, highly digestible, highly watersoluble

Fry feed For 0.5- 0.75 g fry, contain high level of protein

Transition feed High palatability, high energy content, formed with relatively

low digestibility coefficients

Fingerling feed Semi moist feed pellet sizes of 3/ 64- 3/ 32 inch, growth rates

are higher during this stage, high protein and vitamin content


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Type of feed

Grower feeds Given from fingerling stage to market size, contain

less protein and more energy

Brood stock feed Most of the brooders require -3 fatty acids,

protein, energy and vitamin requirement is high,

ascorbic acid level should be high

Low pollution feeds Phosphorus and nitrogen level should be reduced


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Type of feed

Microencapsulated feeds Micro encapsulation is a process in which a

material surrounds and coats another substance

Adopted and developed for larval feeds

Micro capsules are separated into two categories

impermeable and controlled release

The most common and appropriate are cross-

linked proteins and lipid walled microcapsules Primary goal is to reduce the leaching loss


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Feed manufacturing

Basic steps are grinding, mixing, conditioning,

pelleting, cooling, top dressing, sacking, storing,

and shipping

Sacked or bulk ingredients are arrive at feedmills, should be examined for condition

Drugs and medication must be segregated

Ingredients must be stored to protect againstcontamination, moisture and pest damage


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Feed manufacturing

Grinding Most of the ingredients need to be ground before

use

Grinding increases the surface area of ingredientparticles, facilitating mixing and pelleting Grindingis done by hammer mills, pulverizers, attrition mills

Particles are reduced to various sizes, dependingupon the process by which the feed will be pelleted

Ingredients with high lipid content are more difficultto grind than low lipid ingredients.

High lipid ingredients can be combined with lowlipid ingredients


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Feed manufacturing

Mixing To produce a homogenous blend

Ingredients are generally added to the mixer in a

predetermined sequence to ensure adequatemixing

Dry ingredients are first combined, after sufficient

mixing of dried ones liquid ingredients are added

Batch or continuous mixers are common. Type ofmixer includes horizontal ribbon mixers, vertical

mixers, Nanta mixers, turbine mixers


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Feed manufacturing

Conditioning and expansion Done for pelleting and includes thermal and physical

processing

Feed ingredients are kept for very short time about 30 sec

Expansion is a conditioning step, involves steam injectionand mixing

Pelleting Convert the homogenous blend of ingredients into durable

particles and make them suitable for feeding

Compressed Pelleting

Exposed to dry steam for about 5- 25 sec. to increase the temp.to about 850 C and the moisture to about 16% through holes ina metal die

They are cut by a stationary, adjustable knife, fat level shouldbe more than 2- 3%


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Feed manufacturing

Extruded dry pelleting

More versatile than compression pelleting, thereby

allowing for the control of pellet density

Temperature increased up to 125- 150 0 C in a

pressurized conditioning chamber and increasing themoisture content to 20- 24%.

After cooling and drying, the pellet density is typically

0.25- 0.3 g/ cm3

Production of floating pellets requires higher

temperatures and pressures than production ofcompressed pellets


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Feed manufacturing

Immediately after manufacturing, the pellets made bycompression pelleting are cooled and dried by passingthem through a cooler- dryer. Cool air is blown throughthe pellets, which are spread thinly on a moving belt in ahorizontal cooler. Passage through the cooler- dryer

takes 5- 15 minutes Extruded pellets contain more moisture than compressed

pellets and, therefore, need to be heated to reducemoisture to 10% or less. Drying takes approximately 30minutes

Crumbling and screening Dry pellets are crumbled by passing the cooled,

dried pellets through the corrugated rollers of acrumbler

dr. a.p sharma lect2nd

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