Doctor of Philosophy / Department of Animal Sciences and Industry / R. Scott Beyer / Broiler chicken feed is processed. Cereal grains are ground to reduce particle size and
the feed usually is pelleted. When pelleted, broiler diets are steam conditioned and forced
through a die causing varying levels of starch gelatinization. Cereal grain particle size and starch
gelatinization can be controlled during feed manufacturing. Earlier research has shown that
starch gelatinization negatively affects growth performance of 0 to 21 d of age. An experiment
was conducted to determine the effects of corn particle size and starch gelatinization on growth
performance, dressing percentage, and gizzard size when fed to 22 to 42 d of age broilers.
Increasing particle size from 470 to 1240 μm increased body weight gain, dressing percentage,
and relative gizzard size. Starch gelatinization increased relative gizzard size. No interaction
effects were detected. To expand on previous experiments, a trial was conducted to investigate
the effect of starch gelatinization on broiler chick gastrointestinal pH, glucose absorption, and
glucoregulation. Starch gelatinization level affected jejunum pH, with a higher pH reported at
20% starch gelatinization. Increases in starch gelatinization decreased blood glucose and
increased glucagon level. Highest measured glucagon level was reported in broiler chicks fed
the diet with 20% starch gelatinization level diet after 6 hours of starvation. A third experiment
was conducted to determine the effect of starch gelatinization on metabolizable energy and
amino acid digestibility. Increasing starch gelatinization from 0 to 100% increased true
metabolizable energy and fecal output in roosters. No effect was found on apparent
metabolizable energy or amino acid digestibility, with an increase in starch gelatinization from 0
to 20%. Increasing particle size from 470 to 1240 μm had a positive effect on 22 to 42 d growth
performance. A starch gelatinization level of 20% or lower had no effect on metabolizable
energy or amino acid digestion. Older broilers with larger gastrointestinal tracts are unaffected
by 20% gelatinized starch; whereas, 20% gelatinized starch reduced blood glucose and increased
glucagon levels of young broilers. Lower blood glucose and increased glucagon are indicative of
lower glucose storage, and could cause reduced young broiler growth performance when fed
diets with gelatinized starch.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/17152 |
| Date | January 1900 |
| Creators | Rude, Christopher Mark |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
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