Comparative Development of the Small Intestine in the
Turkey Poult and Pekin Duckling1
T. J. Applegate,*,2 D. M. Karcher,* and M. S. Lilburn†
*Department of Animal Sciences Purdue University, West Lafayette, Indiana 47907;
and †Department of Animal Sciences, The Ohio State University, Wooster, Ohio 44691
greater than poults at 1 d of age (P ≤ 0.06), and by 7 d
of age ducklings were 140 g heavier (P ≤ 0.01). Yolk sac
weight was similar at 21 and 25 d of incubation, yet was
significantly lower in ducks at hatch, 1, and 2 d of age
(P ≤ 0.05). In the duckling, jejunum and ileum weights
(3.7× heavier), length (1.6× longer), and density (g/cm;
2.3× more dense) were consistently heavier than in the
turkey from hatch through 7 d (P ≤ 0.01). Histological
sections of the distal jejunum revealed more rapid villus
growth in the duck from 0 to 3 d of age. The combination
of increased intestinal growth (weight and length) and
maturation (villus length) allowed ducks to achieve an
additional 143 g of BW gain during the critical hatch
through 7 d of growth.
ABSTRACT Turkey poults and Pekin ducklings hatch
from eggs of similar weights and have the same incubation periods and body weights at hatch. The male Pekin
duckling, however, can attain a market weight of 3.2 kg
in approximately 6 wk, whereas at the same age, male
turkeys only weigh approximately 2.1 kg. For this study,
fertile turkey eggs (n = 400, mean weight: 87.2 g, range:
85 to 89.9 g) and Pekin duck eggs (n = 565, mean weight:
88.6 g, range: 85 to 92.0 g) were weighed and incubated.
Embryos and hatchlings were sampled during the last
week of incubation, at hatch, and through 7 d of age.
Yolk-free BW of poults were 2.7 g heavier than ducklings
at hatch. Yolk-free BW of ducklings, however, were
(Key words: duck, poult, small intestine, villus)
2005 Poultry Science 84:426–431
straint to optimal early growth in many avian species
(Konarzewski et al., 1989). Physiological maturation (i.e.,
digestive and absorptive functionality) of the digestive
tract occurs largely through increased production of pancreatic and intestinal mucosal enzymes (Nitsan et al.,
1991a,b; Sell et al., 1991) and changes in nutrient transporters (Holdsworth and Hastings-Wilson, 1967; Shehata
et al., 1984; Obst and Diamond, 1992). The physical development of the gastrointestinal tract (i.e., the increase in
surface area of the small intestine), however, may be a
more limiting influence on early growth (Nitsan et al.,
1991a; Sell et al., 1991).
Early posthatch growth of ducklings far exceeds that
of turkey poults even though egg weight, length of the
incubation period, and BW at hatching are similar. Comparisons of intestinal growth and development between
species might provide some insight into the physiological
factors underlying the differences in posthatch growth.
It was hypothesized that anatomical development of
the small intestine is more rapid in the Pekin ducklings
than in the turkey poult, thus allowing for enhanced nutrient use and increased growth during the first week after
hatching. Results previously published by Applegate and
Lilburn on the turkey poult (1999a,b) and Applegate et
al. (1999c) on the duckling are reported in this paper and
were used to evaluate the stated hypothesis.
INTRODUCTION
Turkey poults and Pekin ducklings have similar incubation periods and hatch from eggs of similar weights
with similar body weights at hatch. The commercial male
Pekin duckling, however, can attain a market weight of
3.2 kg in 6 wk or less (Applegate et al., 1999c), whereas
the male turkey will only weigh 2.3 kg at 6 wk of age
(Ferket, 2003).
Even though the small intestine in poults undergoes
considerable development during incubation, it is still
functionally immature at hatch in terms of digestive and
absorptive capabilities (Sell et al., 1991). Although there
has been little reported on intestinal development of
ducklings during embryonic development, the small intestine exhibits accelerated growth relative to the whole
body posthatch (Baranyiova et al., 1983; Gille et al., 1999).
Functional maturation of the small intestine involves morphological and physiological changes and is a major con-
2005 Poultry Science Association, Inc.
Received for publication August 27, 2004.
Accepted for publication November 5, 2004.
1
Purdue University Agricultural Research Program Journal Article
no. 17341.
2
To whom correspondence should be addressed: applegt@
purdue.edu.
426
427
DUCK AND TURKEY INTESTINAL DEVELOPMENT
TABLE 1. Duck and turkey egg weight and egg component comparisons
Egg1
Yolk2
Albumen
Species
(g)
(g)
(%)
(g)
(%)
Duck
Turkey
88.14 ± 0.47
86.63 ± 0.54
28.28 ± 0.40
24.18 ± 0.46
32.10 ± 0.52
27.97 ± 0.59
50.32 ± 0.66
52.64 ± 0.76
57.08 ± 0.56
60.70 ± 0.64
0.04
0.0001
Probability
0.0001
0.03
0.0001
Effect of species
1
Duck: 85- to 92-g eggs from 32- and 44-wk-old hens, n = 565; turkey: 85- to 90-g eggs from 34- and 44-wkold hens, n = 400 (±SEM).
2
Duck yolk and albumen means represent 25 eggs; turkey yolk and albumen means represent 10 eggs (±SEM).
MATERIALS AND METHODS
Fertile commercial turkey eggs (n = 400, average
weight = 87.2 g) from 34- and 44-wk-old hens and Pekin
duck eggs (n = 565, average weight = 88.6 g) from 32- and
44-wk-old hens were collected and incubated separately.
The embryos or hatchlings from each species (n = 5 from
each hen age) were sampled on the following days relative to hatching: −7, −3, 0 (hatch), 1, 2, 3, 5, and 7 for
determination of the residual yolk sac weight and yolkfree BW. A practical corn-soybean meal based diet that
met or exceeded NRC (1994) nutrient recommendations
for each species was fed during the posthatch period.
Birds were housed in electrically heated brooder cages
and had ad libitum access to feed and water. At 0, 1, 2,
3, 5, and 7 d of age, the small intestine was excised beginning at the proximal end of the duodenum and extending
to the ileocecal junction. The duodenal loop and lower
small intestine (jejunum and ileum) were separated,
flushed with 0.9% saline, blotted dry, and weighed. The
length of each segment was also recorded. At 0, 1, and 3
d of age, a 2-cm portion of the distal jejunum (proximal to
Meckel’s diverticulum) was excised from each respective
species (duckling and poult, n = 10), flushed with 0.9%
saline, and fixed in 10% neutral buffered formalin. A 0.5mm section was then processed and embedded in Polyfin
paraffin.3 Paraffin sections (5 or 6 µm) were subsequently
stained with hematoxylin and eosin.
The villus measurements from the distal jejunum sections (n = 10 per species/d) were made from images
obtained from an Olympus IX70 inverted microscope,4
processed with a Vay Tek deconvolution imaging system.5 The actual measurements were made using ImagePro Plus software.6 Villus height (villus tip to crypt junction) and crypt depth (depth of the invagination between
adjacent villi) were determined on 20 villi per bird. As
the age-by-species interaction was significant (P ≤ 0.05)
for all characteristics measured (except yolk sac weight),
the statistical analysis of the differences between species
within each sampling day was determined by ANOVA.7
3
Polysciences Inc., Warrington, PA.
Olympus America Inc., Melville, NY.
5
Vay Tek, Fairfield, IA.
6
Media Cybernetics, Inc., Silver Spring, MD.
7
SAS Institute, Cary, NC.
4
All procedures and protocols were approved by Purdue
University and the Ohio State University Animal Care
and Use Committees.
RESULTS
Duck and turkey egg weights were very similar, but
the actual egg components varied with the turkeys having
a smaller yolk and more albumen than the ducks (Table
1). The probability of species differences was highly significant for yolk weight (P = 0.0001) and for albumen
weight (P = 0.03). Yolk-free BW of poults were 2.7 g
heavier than ducklings at hatch, but this was reversed at
1 d of age when the mean yolk-free BW of ducklings was
3.4 g greater than that of poults (P < 0.05, Table 2). This
difference became progressively greater through the first
week posthatch, and at 7 d ducklings were 140 g heavier
(P = 0.01). Yolk sac weight was similar at 21 and 25 d of
incubation, yet was significantly less in ducklings at 0, 1,
and 2 d of age (P < 0.05, Table 3).
Species comparisons of duodenum length, weight, and
density are presented in Figure 1. The differences in duodenal weight were significant (P < 0.05) only at 0, 2, and
7 d of age with poults having a heavier duodenum at 0
and 2 d. Although the duodenum of a duckling weighs
less for the first 2 d of age, the duodenum weights of
ducklings quickly surpass the duodenal weights of the
poults by 7 d of age (P < 0.05). The duodenum length
was consistently greater in ducklings from 0 through 7
d of age (P < 0.05). The poults consistently had a higher
duodenum density throughout the first week (P < 0.05)
when compared with the ducklings. The duodenal
weights of ducklings and poults were also compared on
a relative basis. The poults were significantly different
from the ducklings from 0 through 7 d of age (P < 0.0001,
Table 4) except for 1 d of age.
In the duckling, jejunum and ileum weight, length, and
density were consistently heavier than the poult from 0
through 7 d of age (P < 0.05, Figure 2) when the lower
small intestine of the duckling was 3.7× heavier, 1.6×
longer, and 2.3× more dense (g/cm). The jejunum-ileum
weights when compared relative to BW showed the ducklings had heavier jejunum-ileums from 0 to 7 d of age (P
< 0.0001, Table 5).
Histological sections of the distal jejunum (Table 6)
revealed that the ducklings had significantly longer villi
428
APPLEGATE ET AL.
TABLE 2. Duckling and poult BW (devoid of the yolk sac) comparisons1
Days relative to hatch
Species
−7
−3
0
1
Duck
Turkey
35.2 ± 0.3
30.6 ± 0.5
46.9 ± 0.7
48.3 ± 1.1
51.4 ± 0.5
54.1 ± 0.9
64.3 ± 1.0
60.9 ± 1.5
0.0001
0.33
0.01
0.06
Effect of species
2
(g)
82.5 ± 1.4
70.0 ± 2.2
3
5
7
113.4 ± 1.5
83.2 ± 2.4
180.6 ± 2.6
115.6 ± 4.1
289.6 ± 3.8
150.0 ± 6.0
0.0001
0.0001
0.0001
Probability
0.0001
1
Duck: 85- to 92-g eggs from 32- and 44-wk-old hens, n = 25; turkey: 85 to 90 g eggs from 34- and 44-wk-old hens, n = 10 (±SEM).
TABLE 3. Duckling and poult yolk sac weight comparisons1
Days relative to hatch
Species
−7
−3
Duck
Turkey
20.31 ± 0.49
20.19 ± 0.77
12.46 ± 0.53
13.29 ± 0.83
0.91
0.41
Effect of species
0
1
(g)
2.39 ± 0.38
0.94 ± 0.14
3.94 ± 0.66
3.01 ± 0.22
Probability
0.05
0.0001
2
3
0.42 ± 0.09
1.54 ± 0.14
—2
1.02 ± 0.09
0.0001
—
1
Duck: 85- to 92-g eggs from 32- and 44-wk-old hens, n = 25; turkey: 85- to 90-g eggs from 34- and 44-wk-old hens, n = 10 (±SEM).
Duckling yolk sac weight was negligible.
2
TABLE 4. Duckling and poult relative duodenum weight comparisons1
Days relative to hatch
Species
0
1
Duck
Turkey
0.66 ± 0.01
0.79 ± 0.02
1.03 ± 0.03
1.05 ± 0.04
0.0001
0.61
Effect of species
2
3
(g/100 g of BW)
1.16 ± 0.03
1.24 ± 0.03
1.65 ± 0.04
1.72 ± 0.05
Probability
0.0001
0.0001
5
7
1.16 ± 0.03
1.87 ± 0.05
1.16 ± 0.04
1.88 ± 0.06
0.0001
0.0001
1
Duck: 85- to 92-g eggs from 32- and 44-wk-old hens, n = 25; turkey: 85- to 90-g eggs from 34- and 44-wk-old hens, n = 10 (±SEM).
and deeper crypts (P < 0.0001) although there was no
significant difference in yolk-free BW at hatch. By 3 d
relative to hatch, the duckling had longer villi height
and deeper crypts. Therefore, ducklings have more rapid
villus growth from 0 to 3 d of age. The large differences
in villus height and crypt depth is shown in Figure 3.
DISCUSSION
As a turkey or duck hen ages, the composition of eggs
changes with an increase in yolk size and a decrease in
the amount of albumen (Applegate and Lilburn, 1996,
1998a,b; Applegate et al., 1998). Within these reports,
Applegate and Lilburn noted an appreciably greater
transfer of dry matter and lipid out of the yolk sac, resulting in heavier BW at hatching, independent of
changes in egg weight. Even if BW differences are not
measurable among hatchlings from different ages of hens,
they may still have a reduced capacity for metabolic homeostasis (Applegate and Lilburn, 1999a; Applegate et
al., 1999). After hatching, structural growth of the small
intestine, however, cannot be directly attributed to age
of the hen alone (Applegate and Lilburn, 1999a,b;
Applegate et al., 1999).
The comparison between species reported herein contained data from studies with turkeys that were in their
2nd (prepeak egg production) and 11th weeks of production (34 and 44 wk of age) vs. those from studies with
ducks that were in their 6th (prepeak egg production)
and 18th weeks of production (32 and 44 wk of age). The
commercial Pekin duck provides for a unique subject for
studying the effects of hen production age on embryonic
and hatchling growth because egg weight can be maintained within a given range with a quantitative feed restriction. Quantitative feed restriction prevents the laying
of excessively large eggs and enhances the hatching uniformity of a flock. The turkey eggs used in this study
were preselected from a larger population of eggs to obtain those within given egg size ranges.
Holub et al. (1994) stated that duck eggs have more
gross energy per gram of egg mass prior to incubation
than chickens and can more efficiently transfer that gross
energy to the embryo during incubation. Within the current studies, the duck eggs contained 4.1% more yolk
429
DUCK AND TURKEY INTESTINAL DEVELOPMENT
FIGURE 1. Duckling (line) and poult (dashed line) duodenum
weight, length, and density (g/cm) comparisons. Duck: 85- to 92-g eggs
from 32- and 44-wk-old hens, n = 25; turkey: 85- to 90-g eggs from 34and 44-wk-old hens, n = 10. *Difference between species is significant
(P ≤ 0.05). Error bars indicate standard error of the mean.
(32.10 vs. 27.97%), thereby suggesting the same statement
could be made relative to the duck containing more gross
energy than that of the turkey. Yolk sac weights, however,
were not different at 21 or 25 d of incubation but were
lighter in ducklings beginning on the day of hatch. This
result is contrary to the findings of Knizetova et al. (1988),
who reported that the proportion of yolk sac (3 to 7%)
of BW at hatching is higher in the duckling than that of
the poult. The report by Knizetova et al. (1988), however,
FIGURE 2. Duckling (line) and poult (dashed line) jejunum-ileum
weight, length, and density (g/cm) comparisons. Duck: 85- to 92-g eggs
from 32- and 44-wk-old hens, n = 25; turkey: 85- to 90-g eggs from 34and 44-wk-old hens, n = 10. *Difference between species is significant
(P ≤ 0.05). Error bars indicate standard error of the mean.
used 75- and 95-g eggs in comparisons with previously
published literature in contrast to the 85- to 92-g eggs in
the current study. Any differences in residual yolk sac
weights on the day of hatch in the current study would
be a result of use of the yolk and were reflected in differences in yolk-free BW. By 3 d of age, the ducklings drastically increased their yolk-free BW (120% increase from 0
d of age), whereas poults only had a marginal increase
(36% increase from 0 d of age).
TABLE 5. Duckling and poult relative jejunum-ileum weight comparisons1
Days relative to hatch
Species
0
1
Duck
Turkey
2.62 ± 0.06
1.56 ± 0.10
4.16 ± 0.08
1.94 ± 0.13
0.0001
0.0001
Effect of species
1
2
3
(g/100 g of BW)
5.24 ± 0.08
5.82 ± 0.08
2.91 ± 0.13
2.82 ± 0.13
Probability
0.0001
0.0001
5
7
5.35 ± 0.19
3.12 ± 0.31
5.47 ± 0.07
2.89 ± 0.11
0.0001
0.0001
Duck: 85- to 92-g eggs from 32- and 44-wk-old hens, n = 25; Turkey: 85 to 90 g eggs from 34- and 44-wkold hens, n = 10 (±SEM).
430
APPLEGATE ET AL.
TABLE 6. Duckling and poult distal jejunum villus height (villus tip to crypt), and crypt depth
(depth of the invagination between adjacent villi) comparisons1
Days relative to hatch
Variable and species
0
1
258.5 ± 5.2
138.1 ± 12.0
0.0001
260.7 ± 6.3
133.1 ± 14.7
0.0001
441.5 ± 12.0
182.2 ± 16.2
0.0001
55.9 ± 1.6
26.5 ± 2.2
0.0001
82.5 ± 2.5
26.1 ± 3.9
0.0001
149.5 ± 2.6
30.0 ± 1.8
0.0001
Villus height
Duck
Turkey
Probability of species effect
Crypt depth
Duck
Turkey
Probability of species effect
3
(µm)
1
Duck: 85- to 92-g eggs from 32- and 44-wk-old hens, n = 25; turkey: 85- to 90-g eggs from 34- and 48-wkold hens, n = 10 (±SEM).
The accelerated growth of the gastrointestinal tract of
poultry following hatching indicates organs and tissues
that fulfill a supply function for achieving early body
development is of great importance to meet the energetic
demands of a body but also limits the body size that can
be reached at that point in time (Mitchell and Smith, 1991;
Sell et al., 1991; Starck, 1998). Uni et al. (1995) stated the
increased volume of villi with age is greater in the jejunum
and ileum than in the duodenum. Applegate et al. (1999)
supported this statement by indicating the villi in poults
from older hens may be more developmentally advanced
in poults at hatch, but posthatch growth of the intestine
is not affected by hen age.
In this experiment, major differences were observed
between the 2 species for weight, length, and density of
the duodenum and jejunum-ileum. Although ducklings
surpassed poults in all 3 of these aspects for the jejunumileum, ducklings never surpassed the poults in duodenum density but did in duodenum length and, finally,
by 7 d of age in duodenum weight. The possible effect
of egg size was removed by making comparisons of the
duodenum and jejunum-ileum weights relative to BW.
On a relative basis, ducklings never surpassed poults in
duodenal weight but easily surpassed poults in weight
of the jejunum-ileum. Therefore, ducklings may have increased length of villi and accelerated growth of those
villi within the jejunum-ileum. Starck (1998) tentatively
concluded that the growth of the gastrointestinal tract is
determined by the number of intestinal crypts and the
size of absorptive surface (villi). The observed massive
differences in villus height and crypt depth between the
ducklings and poults may explain the differences observed in yolk sac weight and yolk-free BW. In the distal
jejunum, ducklings had approximately 5× deeper crypts
and 2.4× higher villi as compared with poults.
Katanbaf et al. (1988) implied the accelerated growth
of the gastrointestinal tract after hatching served the function of a supply organ. Others have asserted that rapid
intestinal growth is a prerequisite for sustained body
growth rates in ducklings (King et al., 2000) and other
bird species (Lilja, 1983). Body size and growth rate at
any point during development are determined by organ
structures and functions (Mitchell and Smith, 1991).
Therefore, the overall development of the animal can be
greatly enhanced or delayed depending on the development and amount of energy placed into supply organs
within the first few days of growth. Presumably, the great
differences observed in intestinal development allow
ducklings to gain an additional 143 g of BW during this 7d period of physiological and metabolic transitions. Other
plausible mechanisms contributing to these dramatic differences in growth, however, should not be overlooked,
including: diet consumption capacity, digestive enzyme
capacity, and nutrient transporter numbers.
In summary, there are no differences observed between
the species in yolk-free BW at hatch, yet there is a drastic
change in yolk-free BW, resulting in heavier ducklings
compared with poults by 3 d of age. Thus, the small
intestine of a Pekin duckling develops more rapidly after
hatching (concomitant with large differences in BW) as
compared with the small intestine of a turkey poult. Much
of this difference was reflected in the weight, length, and
villus height measurements of the jejunum and ileum.
FIGURE 3. Duckling and poult distal jejunum villi comparison at 3
d of age. Sections were 5 µm thick and were stained with hematoxylin
and eosin. Magnification = 100×.
DUCK AND TURKEY INTESTINAL DEVELOPMENT
ACKNOWLEDGMENTS
The authors thank Maple Leaf Farms (Milford, IN) and
Cooper Farms (Ft. Recovery, OH) for their generous donations of fertile eggs used in these experiments.
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