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Samenvatting feed technology Msc animal sciences
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[Meer zien]Voorbeeld 4 van de 41 pagina's
Voorbeeld 4 van de 41 pagina's
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Voorbeeld van de inhoud
Feed technology samenvatting+Exam is made on the laptop
Lecture 1
Grinding is the formation of smaller particles from larger particles by mechanical
processing (pressure, shear). It increases particle surface to volume ratio, which
increases the accessibility for digestive enzymes. It unlocks nutrients for
digestive enzymes and changes physicochemical properties of particles.
Normally reducing particle size (grinding) improves starch accessibility and
therefore higher digestibility.
In chickens gizzard needs larger particles, so it develops the gizzard. If its fully
developed than lower ph (pepsin activity, killing pathogens), stimulates intestinal
motility and smaller particles going into smaller intestine. Also stimulates
pancreatic enzymatic secretion
Why agglomerate (formation of larger particles from smaller particles):
-Losses at factory, transport, storage and farm
-Health (dust) of human and animals
-Efficient handling
-Balanced intake
-Physical properties
Agglomeration reduces feed wastage and increases digestibility.
Mash versus pelleted feed in broilers. If they select (mash) more feed wastage,
they also have an increase in time eating. If you have a pelleted feed you need
less energy, so lysine to energy ratio increases, so you need more lysine. Pellet
form, chickens will consume more, and have a higher weight gain. Empty gizzard
weight is higher when feeding more coarse particles, but lower when feeding
pellets.
Lecture 2
Starch
2 types of glucose polymers:
-Amylopectin -> highly branched
-Amylose -> unbranched
Most amylose (of total starch) are in peas and maize, and therefore lower
amylopectin content. Wheat, and potato contain high amylopectin and lower
amylose.
In general for normal ingredients starch is coming 20-30% coming from amylose,
and 70-80 % from amylopectin.
Starch sources can differ in: size, shape, pores, crystalline type, amylose content
etc. It has an impact on digestion kinetics.
,Starch gelatinization process= swelling and rupture (breaking) of starch granules
At a high moisture content, there will be a peak of energy consumption, because
of the energy needed to change gelatinize starch. Amylopectins being changed
into other structures (energy needed), after this starch gelatinized and peak is
gone.
Lower moisture content means that there is more energy needed to gelatinize the
starch. Higher temperature means easier starch gelatinization. Not too high,
otherwise not an efficient gelatinization of starch
Certain temperature is needed, to let the gelatinization process start: starch
granules being to absorb water and swell. Heat disrupts hydrogen bonds,
allowing water to penetrate and it expands.
Crystaline structures makes starch harder to digest (more amylopectins)
Gelatinisation temperature:
Excess water: 50 to 70 degrees
Under 35% water: more than 100 degrees needed.
Ratio of 0.3 water: 1 starch as to initiate starch gelatinization during heating
Starch molecules more available for a-amylase -> easier to digest starch
molecules.
Opposite process of gelatinization: retrogradation
Retrogradation= cooling -> gelatinized starch molecules re-associate into
partially ordered structures. So creating more structures instead of breaking them
down.
Types of resistant starch:
RS1 physically inaccessible
RS2 Native (resistant from origin)
RS3 retrograded (processing
RS4 chemically modified
Digestibility for resistant starch is lower compared to normal digestible starch.
,Conditioning and pelleting have small effect on starch gelatinization, is because
of the small amount time, temperature and moisture level.
When you cook barley or wheat, starch gelatinization degree will be much higher
when processing it raw. Cooking didn’t have a effect digestibility of both
products.
Digestibility of starch when extruding (cooking) is higher and digestibility rate is
faster than raw materials.
, For some animals (like growing pigs, that have higher amylase activity)
gelatinization of starch is not needed, because animals can already digest these
starch by themselves.
Protease= a digestive enzyme. Cereals contain protease inhibitors.
Process soja beans, because facilitating nutritional value and maintain safety.
Some legume species there is an increase in digestibility when cooking, but some
decrease in digestibility. This is caused, because of denaturation of protease
inhibitors (protein of themselves, if you can inactivate these there is
improvement in digestibility. This is protein specific. It can also be caused by
cross-linking proteins, renaturation proteins (new structures being formed) or
aggregation of proteins (proteins sticking together).
Each protein has a specific denaturation temperature.
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