The Relation Between Starch Digestion Rate and Amino Acid Level
for Broiler Chickens1

R. E. Weurding,*,†,‡,2 H. Enting,* and M. W. A. Verstegen‡
*Institute for Animal Nutrition ‘De Schothorst’, Lelystad, The Netherlands; †Brameco ZON, Eindhoven, The Netherlands;
and ‡Animal Nutrition Group, Wageningen University & Research Center, Wageningen, The Netherlands
ABSTRACT Digestion coefficients of nutrients give information
about the amount of nutrients available to the
animal but not about the rate or site of absorption. Gradual
digestion of starch may have an amino acid sparing
effect and therefore enhance growth efficiency of broiler
chickens. A growth trial was performed with 6,800 broiler
chickens from 9 to 30 d of age to investigate interactions
between starch digestion rate and amino acid level. Birds
were fed either a pea-corn-based diet (slowly digestible
starch) or a tapioca-corn-based diet (rapidly digestible
starch). Both diets were formulated with five levels of
digestible lysine, varying from 8.5 to 11.0 g/kg. The minimal
levels of other amino acids varied accordingly. Starch
(Key words: starch digestion rate, amino acid level, broiler chicken, pea, tapioca)
2003 Poultry Science 82:279–284
INTRODUCTION
Feed evaluation in monogastric animals is based on digested
nutrients. Digestion coefficients of nutrients at the
terminal ileum give information about the amount of nutrients
available to the animal but not about the site or the
synchronization of availability of different nutrients. The
major part of starch is digested in the upper part of the
small intestine. Diets with rapidly digestible starch may
result in elevated plasma glucose levels when other nutrients
are not yet absorbed, which may have consequences
for protein utilization. Diets with similar amounts of digestible
nutrients, but differences in digestion kinetics, may
result in different performances.
In ruminant nutrition, the importance of the kinetics of
carbohydrate and protein digestion in the rumen has long
been recognized. In human nutrition, the glycemic index
of foodstuffs is used to manipulate glucose absorption
rate in order to prevent metabolic disorders or to enhance
athlete performance (Brand-Miller, 1999). We have ob-
2003 Poultry Science Association, Inc.
Received for publication February 14, 2002.
Accepted for publication October 8, 2002.
1Funded by the Dutch feed cooperatives and the Dutch Technology
Foundation STW (project no. WPR66.4050).
2To whom correspondence should be addressed: e.weurding@
agrifirm.nl.
279
source did not affect feed intake (2,213 g), but weight
gain was consistently higher for birds on pea-corn diets
than for those on tapioca-corn diets (1,426 vs. 1,400 g; P
< 0.01). Feed conversion was better (P < 0.01) for birds
on pea-corn diets (1.55) than for birds on tapioca-corn
diets (1.58). The difference in feed conversion between
birds on pea-corn and tapioca-corn diets was greater with
lower amino acid levels (0.043) than with higher amino
acid levels (0.019) in the diet (P = 0.11). This interaction
was more pronounced during the first 9 d of the experiment
(P < 0.05). It was concluded that feeding slowly
digestible starch improved protein and energy utilization
in broiler chickens.