AABArchives Animal BreedingAABArch. Anim. Breed.2363-9822Copernicus PublicationsGöttingen, Germany10.5194/aab-61-373-2018Digestive tract morphometry and breast muscle microstructure in spent breeder ducks maintainedin a conservation programme of genetic resourcesDigestive tract morphometry and breast muscle microstructureKokoszyńskiDariuszkokoszynski@gmail.comhttps://orcid.org/0000-0002-6642-1129SalehMohamedBernackiZenonKotowiczMarekSobczakMałgorzataŻochowska-KujawskaJoannaStęcznyKamilDepartment of Animal Sciences, Faculty of Animal Breeding and Biology,
UTP University of Science and Technology, Mazowiecka 28, 85-084 Bydgoszcz,
PolandDepartment of Poultry and Animal Production, Faculty of Agriculture,
Sohag University, Street Nasser City, 82524 Sohag, EgyptDepartment of Meat Science, Faculty of Food Sciences and Fisheries,
West Pomeranian University of Technology, Kazimierza Królewicza 4,
71-550 Szczecin, PolandDariusz Kokoszyński (kokoszynski@gmail.com)30September201861337337822June201823August201831August2018This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/This article is available from https://aab.copernicus.org/articles/61/373/2018/aab-61-373-2018.htmlThe full text article is available as a PDF file from https://aab.copernicus.org/articles/61/373/2018/aab-61-373-2018.pdf
The objective of this study was to compare three genetic groups of ducks: P9
(French Pekin), K2 (bred from wild mallards – Anas platyrhynchos L.
and Pekin duck), and KhO1 (hybrid of Khaki Campbell drake and Orpington Fauve
duck) after two breeding seasons for body weight and length, length of
intestine and its segments, percentage of other internal organs, and breast
muscle microstructure. The study used 60 ducks, 20 birds (10 males and
10 females) from each genetic group. At 110 weeks of age, P9 ducks exhibited
significantly (p<0.05) greater body weight and length, and length
of intestine and its segments (except for colon length) compared to K2 and
KhO1 ducks. KhO1 ducks had significantly shorter jejunum and ileum compared
to K2 birds. The lighter K2 and KhO1 ducks had significantly greater relative
length of intestine and its segments. In P9 ducks, liver, heart, and gizzard
were heavier and spleen percentage in body weight significantly lower than in
K2 and KhO1 birds. KhO1 ducks had a significantly higher percentage of
proventriculus compared to the other duck groups. The different genetic
origins of the ducks had no effect on microstructural characteristics of
m. pectoralis superficialis except for perimysium and endomysium
thickness. Our study provided information about differences in the digestive
tract morphometry and breast muscle microstructure of ducks from three
genetic groups after two reproductive seasons, which are maintained in a
conservation programme of genetic resources in Poland.
Introduction
The structure of the digestive tract is indicative of the rate of digestion.
Intestinal length in mature hens and turkeys is 5–6 times, and in ducks and
geese 4–5 times, as high as their body length. In other monogastric farm
animals (pigs and horses), the intestine to body length ratio is much higher,
25:1 and 20:1, respectively (Langenfeld, 1992). Research results
(Szczepańczyk et al., 2000; Hassouna, 2001) show that individual birds
differ considerably in the weight, length, and diameter of the intestine and
its segments. This variation is determined mainly by genetic (species, breed,
line, hybrid) and environmental factors, especially the amount and type of
ingested food as well as thermal conditions. Other factors affecting
intestinal development are body size, sex, age, health status, and
physiological status of birds (King et al., 2000; Szczepańczyk et al.,
2000; Wasilewski et al., 2015). Applegate et al. (2005) found jejunum and
ileum to be 3.7-fold heavier and 1.6-fold longer in fast-growing Pekin ducks
aged 7 weeks than in almost 2-fold lighter turkey poults of the same age.
Kasperska et al. (2012) observed that relative length
(cm 100-1 g BW) of the small intestine,
caecum, and total intestine decreased significantly with the age of guinea
fowl. In turn, Szczepańczyk et al. (2000) noted that birds consuming
animal origin food had a relatively shorter small intestine in relation to
body length compared to seed eaters, and that the energy concentration had an
effect on the amount of ingested feed.
Due to its functions such as food content storage,
digestion, and absorption of
nutrients from food, the digestive tract has a considerable impact on animal
body growth and development as well as on chemical composition, nutritive and
dietetic value, and other muscle tissue quality traits.
Muscle fibre microstructure, in particular the percentage of white and red
fibres, their diameter and contraction, the amount and distribution of the
connective tissue, and the amount of its different fractions (epimysium,
perimysium) largely determine meat tenderness, which is considered the most
important trait encouraging the consumption of meat (Elminowska-Wenda and
Szpinda, 2011). Muscle fibre structure is genetically determined and varies
according to poultry species (Kissling, 1977). Breed, age, diet, health,
housing system, and physical activity also affect the diameter and percentage
of white and red fibres (Choi and Kim, 2008).
The results for digestive tract morphometry and breast muscle microstructure
in P9 ducks (French Pekin), K2 (bred from wild mallards – Anas platyrhynchos L. and Pekin duck), and KhO1 (hybrid of Khaki Campbell drake
and Orpington Fauve duck) after two reproductive seasons will be presented
for the first time. The above genetic groups form 3 out of 10 unique flocks
of ducks (the only ones in Poland and the world) included in the genetic
resources conservation programme. In keeping with the Conservation Programme
for Farm Animal Genetic Resources in Poland, breeder flocks of ducks
maintained at the Waterfowl Genetic Resources Station are liquidated after
two reproductive seasons.
The aim of the study was to determine the differences (morphological and
microstructural diversity) between conservation breeds of ducks.
Materials and methods
The study material consisted of 60 ducks from three genetic groups: P9
(French Pekin), K2 (bred from wild mallards – Anas platyrhynchos L.
and Pekin duck), and KhO1 (hybrid of Khaki Campbell drake and Orpington Fauve
duck) aged 110 weeks, after two reproductive seasons. Before slaughter, birds
were penned on litter in a windowless, environmentally controlled confinement
building. Ducks were fed ad libitum a complete diet for breeder
ducks. The diet contained 18.5 % CP and 11.1 MJ metabolizable energy per
kilogramme. Birds were allowed 24 h access to water. The study was approved
by the Local Ethics Committee in Bydgoszcz (decision no. 8 of 2010).
At the age of 110 weeks, when the birds completed their second reproductive
season, 20 birds (10 drakes and 10 ducks) were randomly selected from each of
the liquidated P9, K2, and KhO1 flocks, and each bird was individually
weighed to the nearest 5 g using an electronic balance (Axis BD 15S, Axis,
Gdańsk, Poland). After weighing, the body length of the ducks was
determined by tape-measuring with an accuracy of 1 mm the distance between
the first cervical vertebra (atlas) and the posterior superior tuberosity of
the ischium.
Following the live measurements, the birds were subjected to on-farm
slaughter, defeathering, and evisceration. During the evisceration, the
digestive tract and other internal organs of the ducks were separated. The
lengths of the duodenum, jejunum, ileum, both caeca, and the colon were
tape-measured with an accuracy of 1 mm. The data concerning total intestinal
length (sum of intestinal segments) and body length were used to calculate
the intestinal length to body length ratio.
After removing the viscera from the body cavity, proventriculus (without
digesta), gizzard (without digesta), liver (without gallbladder), heart, and
spleen were separated from each duck and weighed with an accuracy of 0.001 g
on a Medicat M160 electronic balance, and their percentages in pre-slaughter
body weight were determined.
For histological analysis, samples of superficial pectoral muscle (m. pectoralis superficialis) were taken from 10 females and 10 males of each
genetic group. From each bird aged 110 weeks, three sections (0.5×0.5×1 cm each) were taken from the middle part of m. pectoralis superficialis, parallel to muscle fibre orientation. The samples were fixed
with Sannomiya solution, dehydrated in alcohol and benzene, and embedded in
paraffin blocks. The blocks were sectioned with microtome, and sections of
10 µm were placed on glass slides and counterstained with
hematoxylin and eosin (Burck, 1975) and embedded in Canada balm. The size of
muscle tissue microstructural elements was measured using the MultiScanBase
v. 13 image analysis system (Computer Scanning System Ltd, Warsaw, Poland).
Fibre cross-section area, fibre perimeter and its horizontal (H) and vertical
(V) diameter, and thickness of perimysium and endomysium were measured. The
determinations were made on three m. pectoralis superficialis
preparations per bird. Around 200 muscle fibres were measured in each
preparation and 150–200 measurements of the connective tissue thickness
(perimysium and endomysium) were made. A magnification of 100× was
applied. Based on the data for horizontal and vertical diameters of the
muscle fibre, the H : V diameter ratio was calculated.
The numerical data were statistically analysed using SAS ver. 9.4 software
(SAS Institute Inc., 2014). Arithmetic means and standard error (SE for all
groups) were calculated for all the analysed traits. Significant differences
between the arithmetic means for body weight and length, morphometric
characteristics of the intestine, and breast muscle (m. pectoralis superficialis) microstructure were
verified with Tukey's test at P≤0.05.
Results and discussion
The average body weight of 110-week old P9 ducks was significantly higher (P≤0.05) than that of K2 and KhO1 birds (Table 1). Such great differences
in the ducks' body weight were due to their different origins. K2 ducks were
created from mallards and Pekin ducks with low body weight, which caused a
significant reduction in their body weight. KhO1 ducks were developed by
crossing a Khaki Campbell male (layer duck) with an Orpington female (general
purpose duck), the breeds that have not been improved for meat traits,
including high body weight. The body weight of 110-week old ducks from the
analysed genetic groups was higher compared to the body weight of the ducks
of the same genotype evaluated at 7 weeks of age by Kisiel (2003), which may
be indicative of the continued growth of the ducks from these genetic groups
after 7 weeks of age. Gornowicz and Szukalski (2015), who analysed the body
weight of K2 (Mini Duck), P8 (Danish Pekin), P9 (French Pekin), P33 (Polish
Pekin), and LsA ducks (English Pekin) under the conservation programme in
Poland, also observed that the above genetic groups differed in body weight
at the age of 8 weeks. The studied birds, in particular K2 and KhO1 ducks,
may be useful for production of lighter carcasses, which are increasingly
sought by duck meat consumers.
Body weight, body, and intestine length and their ratio in spent
ducks.
GenotypeBody weightLength of (cm) Intestine:(g)BodyIntestinebodyratioP92981a45.6a244.8a5.4aK21744b38.9c201.7c5.2aKhO11875b41.0b181.1b4.4bPooled SE77.50.44.30.1
a,b,cIndicate significant differences among groups (P≤0.05).
The compared genetic groups of the ducks, which from the 1980s have been
selected for conformation and health but not for productive traits, also
exhibited significant differences in body length, total intestinal length,
and the intestine length to body length ratio, which shows their distinctness
and uniqueness in terms of these traits. P9 ducks had significantly (P≤0.05) longer body and intestine compared to K2 and KhO1 birds. K2 ducks
had significantly shorter body length than KhO1 ducks, and KhO1 ducks
significantly shorter intestine than K2 ducks. The intestine length to body
length ratios were lower than those reported by Wasilewski et al. (2015) for
young Pekin ducks. Kokoszyński (2011) observed that four commercial Pekin
duck hybrids (Star 53 H.Y., AP54, PP54, and PP45) differed significantly in
body weight and length at 7 weeks of age. PP45 and PP54 ducks, which were
created by crossing conserved P44 and P55 ducks, had lower body weight and
greater body length compared to Star 53 H.Y. and AP54 birds. In the study by
Wasilewski et al. (2015), Pekin SM3 Heavy and AF51 hybrids had longer
intestine than the evaluated P9, K2, and KhO1 ducks, which have not been
selected for productive traits since the 1980s. In the study by Schmidt et
al. (2009) with Ross 708 chickens (modern line) and UIUC (heritage line),
jejunum and ileum length was around 20 % longer in Ross 708 chickens than
in UIUC chickens, which have not been selected since the 1950s. In another
experiment (Watkins et al., 2004), better small intestine development was
noted in young mallard ducks than in domesticated Pekin ducks.
The length of intestine segments is presented in Table 2. P9 ducks with the
highest body weight at 110 weeks had significantly (P≤0.05) longer
duodenum, jejunum, ileum, and caecum compared to K2 and KhO1 birds. KhO1
ducks had significantly shorter jejunum and ileum compared to K2 birds. In
addition, P9 ducks had longer colon than K2 and KhO1 birds. However, this
difference was not significant. To date, the morphological traits of the
intestine have not been determined in ducks after two reproductive seasons.
Watkins et al. (2004) report, however, that in Pekin ducks, morphological and
functional development of the digestive tract is terminated after 7 weeks of
age. An earlier study with young Pekin ducks (6–8 weeks of age) found
greater (Jamroz et al., 2001; Wasilewski et al., 2015) lengths of individual
intestine segments compared to the analysed ducks after two reproductive
seasons.
Length of intestine segments in spent ducks.
GenotypeLength of (cm) DuodenumJejunumIleumCaecumColonP932.2a80.3a83.0a37.1a12.2K227.4b65.5b68.1b30.8b9.9KhO127.6b56.0c59.6c29.1b8.8Pooled SE0.51.51.60.72.9
a,b,cIndicate significant differences among groups (P≤0.05).
Relative length of intestine segments in spent ducks.
GenotypeLength of (cm) 100-1 g BW DuodenumJejunumIleumCaecumColonTotalP91.08b2.69b2.78c1.24c0.41c8.21cK21.57a3.76a3.90a1.77a0.57a11.56aKhO11.47a2.99c3.17b1.55b0.47b9.65bPooled SE0.030.080.080.040.040.16
a,b,cIndicate significant diffgerences among groups (P≤0.05).
Weight and proportion (%) in the body weight of main internal
organs in spent ducks.
GenotypeLiverHeartProventri-GizzardSpleenculusWeight of (g) P962.6a17.9a8.268.5a1.1K229.0b11.2b6.045.3b1.0KhO134.0b12.0b7.057.8c1.0Pooled SE2.80.50.30.30.1Proportion (%) in body weight P92.10.600.28b2.30.04bK21.70.640.34b2.60.06aKhO11.80.640.37a3.10.05aPooled SE0.070.010.010.070.01
a,b,cIndicate significant differences among groups (P≤0.05).
The present results demonstrate considerable differences between the compared
genetic groups of the ducks aged 110 weeks in relative length of the
intestine and its segments (Table 3). Lighter K2 and KhO1 duck had relatively
greater total intestine length and length of its segments compared to P9
ducks. Furthermore, K2 ducks with the lowest body weight had greater relative
length (cm 100-1 g BW) of jejunum, ileum, caecum, colon, and total
intestine compared to KhO1 birds. The highest relative length of the
intestine and its segments was calculated for K2 ducks, and the lowest for
the heaviest P9 ducks. The results obtained for the relative length of the
intestine and its segments in the studied ducks were higher than the values
reported for 7-week old Pekin ducks (SM3 Heavy hybrid) by Stęczny et
al. (2017).
The different genetic origin of the analysed ducks had a significant (P≤0.05) effect on the heart, gizzard, and liver weight. P9 ducks had
significantly heavier hearts, gizzards, and livers compared to K2 and KhO1
ducks. In addition, KhO1 ducks had significantly higher gizzard weight than
K2 birds (Table 4). The compared duck groups did not differ in proventriculus
and spleen weight.
Microstructural characteristics of m. pectoralis superficialis in spent ducks.
a,bIndicate significant differences among groups (P≤0.05).
The percentage of heart, gizzard, and liver in the body of the ducks of
different genetic origin was similar, with no significant differences
(Table 4). KhO1 ducks had a significantly higher percentage of
proventriculus, and P9 ducks a significantly lower percentage of spleen
compared to the other duck groups under study. Makram et al. (2017) observed
significant differences in gizzard and liver percentage (P≤0.01) and in
heart percentage (P≤0.05) in Sudani, Muscovy, and Pekin ducks from
parent flocks at marketing age. The heart and liver percentage of Muscovy and
Pekin ducks investigated by Makram et al. (2017) was higher than in P9, K2,
and KhO1 ducks from this experiment. In another study (Wasilewski et al.,
2015), liver and heart percentage was lower and gizzard percentage higher in
7-week old Pekin ducks compared to the ducks aged 110 weeks. Bartyzel et
al. (2005) noted higher heart percentage (males – 0.76 %, females –
0.69 %) in wild mallards weighing 1320 g (males) and 1250 g (females)
compared to Pekin males (BW = 3128 g, heart = 0.62 %) and
females (BW = 3143 g, heart = 0.60 %). Oh et al. (2015) reported
similar spleen percentage in the bodies of 6-week old Pekin ducks compared to
the studied ducks at 110 weeks of age.
The compared genetic groups of the ducks at the age of 110 weeks did not
differ significantly in the microstructural characteristics of m. pectoralis superficialis, except for
thickness of perimysium (connective tissue surrounding a muscle fibre
bundle) and endomysium (connective tissue surrounding a single muscle fibre)
(Table 5).
The muscle fibres of the lighter K2 and KhO1 ducks were characterized by
smaller area and diameter (P>0.05) but significantly greater
perimysium (K2 ducks) and endomysium (K2 and Kh01 ducks) thickness compared
to P9 birds. The studied microstructural characteristics largely determine
meat tenderness, which is considered the most important characteristic
influencing its consumption. Hašcik et al. (2006) reported smaller muscle
fibre diameter of m. pectoralis major in the wild duck
(21.8 µm) weighing 1026.4 g compared to the domestic duck
(28.2 µm) weighing 2107.0 g, which supports the present results.
In the study by Kokoszyński (2011), Star 53 HY ducks, characterized by
faster growth rate and higher body weight at 8 weeks of age, had greater
diameter of white and red muscle fibres compared to the slow-growing and
lighter PP45 and PP54 ducks. However, Bernacki et al. (2008) did not observe
significant differences between 7-week old Star 63, PP54 (Pekin hybrids), and
CaA15 (Dworka – crosses of Cayuga drake and Pekin female) ducks of different
body weight in terms of the muscle fibre diameter of the pectoralis
superficialis muscle. In turn, Witkiewicz et al. (2004) noted that selection
for increased muscling in A44 and P66 breeding ducks negatively affected the
microstructure of their breast muscles, because P33 and K2 genetic resources
ducks unimproved for meat traits had more red muscle fibres and lower
diameter of white and red fibres, which is more favourable for the consumers
of duck meat. Earlier findings (Muhlisin et al., 2013; Wasilewski, 2018) show
that native duck
carcasses and meat are highly suitable for producing quality and regional
food products that are safe and wholesome due to their nutritive and dietetic
attributes.
Conclusions
It is concluded that the compared genetic groups of the ducks of different
origin at the age of 110 weeks differed significantly in body weight, body
length, and length of the intestine and its segments. Duck genotype had a
significant effect on heart, gizzard, and liver weight, and on proventriculus
and spleen percentage in the body.
The different origin of the birds had no influence on the microstructural
characteristics of the superficial pectoral muscle except for perimysium and
endomysium thickness. The breast muscles of K2 and KhO1 ducks had smaller
area and muscle fibre diameter as well as greater endomysium and perimysium
thickness compared to P9 birds.
The data are available from the corresponding author upon
request.
DK wrote the manuscript and developed the methodology, made the
description of the methods used to determine the studied traits for
methodology and laboratory analyses, performed the calculations, and assumed
primary responsibility for the final content, MS made the description of the
methods used to determine the studied traits for methodology, performed the
research, and analysed the data, and ZB read and made the corrections, wrote
the manuscript and developed the methodology, and made the description of the
methods used to determine the studied traits for methodology and laboratory
analyses. MS performed the research, made laboratory analyses, and analysed
the data, and MK, MS, JZK, and KS made the description of the methods used to
determine the studied traits for methodology and laboratory analyses, and
performed the research. Finally, all the authors commented on the early and
final responses to the manuscript.
The authors declare that there is no conflict of
interest.
Acknowledgements
This study was realized from statutory research fund BS-13/2009
assigned by the Polish Ministry of Science and Higher
Education. Edited by: Steffen
Maak Reviewed by: Emilia Mróz and one anonymous referee
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