1. Feeding and Excreta Collection Techniques in Metabolizable
Energy Assays for Ducks1
O. ADEOLA,2 D. RAGLAND, and D. KING
Department of Animal Sciences, Purdue University, West Lafayette, Indiana 47907
Feeding and excreta collection tech- to each of three test ingredients (corn, dehulled oats, and
ABSTRACT
niques, lasting 102 h, for the determination of ME in wheat) and four ducks were assigned to be deprived of
feed ingredients for ducks are described. Eight and 32 h feed for estimation of endogenous losses of nitrogen and
after feed withdrawal, all ducks received 30 g of energy. In Experiment 2, six ducks were assigned to
dextrose in 100 g of water by orogastric administration. each of two test ingredients (corn and sorghum) and six
By orogastric administration, ducks received 30 g of test ducks were assigned to be deprived of feed. Ducks lost
ingredients or dextrose (for ducks used in estimation of an average of 537 g (Experiment 1) and 462 g
endogenous losses of energy and nitrogen) in 100 g of (Experiment 2) during the 102-h experimental period
water at 48 and 54 h after feed withdrawal. The and all the lost weight was regained within 7 d of return
collection of excreta involved suturing a threaded plastic to full feed. Losses of nitrogen (milligrams per duck per
retainer ring to the vent and screwing a Whirl-Pak™ 54 h) were 292 (Experiment 1) and 461 (Experiment 2)
plastic bag, mounted on the top portion of a Playtex™ and energy (kilocalories per duck per 54 h) were 12.12
and 22.26 in feed-deprived group. The determined
baby nurser set plastic bottle cut off 3 cm below the
AMEn and TMEn for corn were 3.245 and 3.407, and
threads, to the retainer ring. Excreta were collected by
replacing the Whirl-Pak™ bags at 54, 60, 72, 84, 96, and 3.210 and 3.517 kcal/g for Experiments 1 and 2,
102 h after feed withdrawal. In each of two experiments, respectively. For dehulled oats, wheat, and sorghum, the
ducks with an average weight of 3.7 kg were assigned to determined AMEn and TMEn were 3.464 and 3.625,
treatments. In Experiment 1, four ducks were assigned 3.150 and 3.312, and 3.363 and 3.670 kcal/g, respectively.
(Key words: duck, excreta collection, metabolizable energy assay, harness)
1997 Poultry Science 76:728–732
reported by Revington et al. (1991). We made several
INTRODUCTION
unsuccessful attempts to apply the excreta collection
Diet formulation for the duck employs ME values technique reported by Revington et al. (1991) in duck
obtained from nutritional studies of domestic chicken. ME assays. This communication reports the results of
This formulation occurs because limited information is two experiments in which techniques were developed
available on the duck and problems are normally for tube-feeding and collecting excreta in ME assays
encountered in collecting highly liquid excreta in duck with ducks.
ME assays. Assays for AME in feed ingredients for birds
commonly rely on total collection of excreta in trays
MATERIALS AND METHODS
placed under the birds housed in cages. Collection of
highly liquid excreta in trays placed under the ducks is
The excreta collection apparatus was fabricated using
subject to error due to splatter arising from contact of
materials from the Playtex™3 baby nurser set. Threaded
forcefully ejected excreta with trays and contamination
plastic retainer rings from the nurser set with a
with feed, dander, or scales.
4.3-cm diameter hole in the center were modified by
A collection device suitable for total excreta collection
drilling 12 2-mm holes around the periphery as in the 12
in chickens that appeared to be suitable for ducks was
points on a clock. Sixteen-week-old White Pekin male
ducks were surgically fitted with the modified plastic
retainer rings. During surgical fixation of the retainer
Received for publication September 27, 1996.
rings, ducks were restrained in a Plexiglas box (8-mm
Accepted for publication December 16, 1996.
wall thickness, 15 cm × 17 cm × 30 cm) and a
1Journal paper Number 15223 of the Purdue University Agricul-
tural Research Programs. 5-cm zone of feathers adjacent to the vent was removed
2To whom correspondence should be addressed.
to expose the skin. The skin was then sanitized with a
3Playtex Products, Dover, DE 19901.
dilute solution of chlorhexidine diacetate (Nolvasan4).
4Fort Dodge Laboratories, Inc., Fort Dodge, IA 50501.
728

2. 729
METABOLIZABLE ENERGY ASSAYS FOR DUCKS
TABLE 1. Feeding and collection schedule
Hours after feed
Day Time withdrawal Operation
(h) (h)
1 0700 0 Food withdrawn
1 1500 8 Ducks fed dextrose solution (30 g/100 g water)
2 1500 32 Ducks fed dextrose solution (30 g/100 g water)
3 0700 48 Ducks fed (30 g/100 g water) appropriate feedstuff
Ducks from which fasting energy loss is determined fed dextrose solution (30 g/100 g water)
Whirl-pak™ bags placed through the bore of plastic bottle, screwed to retainer rings sutured to
the vents
Excreta collected and frozen by replacing Whirl-Pak™ bags
3 1300 54
Ducks fed (30 g/100 g water) appropriate feedstuff
Ducks from which fasting energy loss is determined fed dextrose solution (30 g/100 g water)
Excreta collected and frozen by replacing Whirl-Pak™ bags
3 1900 60
Excreta collected and frozen by replacing Whirl-Pak™ bags
4 0700 72
Excreta collected and frozen by replacing Whirl-Pak™ bags
4 1900 84
Excreta collected and frozen by replacing Whirl-Pak™ bags
5 0700 96
Excreta collected and frozen by replacing Whirl-Pak™ bags
5 1300 102
The area in which the retainer ring was to be sutured withdrawal, the ducks assigned to the feed deprived
group for estimation of endogenous losses were tube-fed
was then infused in the dorsal, ventral, and lateral
30 g of dextrose in 100 g of water. All ducks were fitted
quadrants around the vent with 2% lidocaine hydrochlo-
with their respective collection vessels at the time of the
ride to desensitize the skin for suturing. The retainer
first feeding of test ingredients and excreta was collected
rings were then sutured to the vent area using a
for 54 h as shown in Table 1 (Hours 48 to 102). The
continuous suture pattern with the retainer rings
feeding, surgical, and collection protocols were ap-
anchored in place by passing the needle and suture
proved by the Purdue University Animal Care and Use
through 2-mm holes drilled in the periphery of the
Committee.
retainer rings. Ducks were used in experiments approxi-
Ducks were weighed and sorted according to weight
mately 72 h after suturing retainer rings to the vents. A
and placed in stainless-steel cages (0.66 m × 0.66 m) such
plastic bottle of the nurser set was cut to a length of 3
that the average weight in each treatment was similar.
cm below the threads on the bottle. During collection,
Whirl-Pak™5 bags were then placed through the bore of Ducks were housed in a facility in which a temperature
of approximately 25 C was maintained and 24 h light /d
the bottle and the flaps of the bag overlaid to the sides
was provided. In Experiment 1, four ducks were
of the bottle covering the threads. The bottle and Whirl-
Pak™ bag were then screwed onto the modified retainer assigned to each of three test ingredients (corn, dehulled
oats, and wheat) and four ducks were assigned to be
ring attached to the bird with the threads of the ring and
bottle securing the bag in place. The Whirl-Pak™ bags deprived of feed for estimation of endogenous losses of
nitrogen and energy. In Experiment 2, six ducks were
containing excreta were changed as indicated in Table 1.
assigned to each of two test ingredients (corn and
Tube-feeding apparatus consisted of a 60-mL
catheter-tip syringe and a 35-cm long Nalgene™6 sorghum) and six ducks were assigned to be deprived of
feed for estimation of endogenous losses of nitrogen and
tubingwith an inside diameter of 8 mm. Forty-eight
energy. The group of ducks used in Experiment 1 was
hours prior to feeding the test ingredients, feed was
different from that used in Experiment 2. An excreta
withdrawn from all ducks. All test ingredients were
sample from each duck was dried at 55 C for 48 h and
ground through a 0.5-mm screen prior to feeding.
ground through a 0.5-mm screen prior to analysis. Dry
Feeding was done by mixing 30 g of test ingredient with
matter of the test ingredients and all excreta samples
80 g of deionized water in a 125-mL beaker. Ducks were
(previously dried at 55 C for 48 h) was determined by
intubated and the gruel was poured into the
drying the samples at 110 C for 24 h. Nitrogen content
60-mL syringe and pumped into the crop with a
of test ingredients and excreta was determined by the
plunger. The beaker was rinsed with 20 g of deionized
combustion method using the Model FP2000 nitrogen
water, poured into the syringe and pumped into the
analyzer.7 Energy content of test ingredients and excreta
crop. The feeding and excreta collection schedule is
was determined by bomb calorimetry using an adiabatic
presented in Table 1. At 48 and 54 h after feed
calorimeter.8
The AME, AMEn, TME, and TMEn of the test
ingredients were calculated as follows: AME = (EI – EO)
÷ FI; AMEn = AME – (8.22 × ANR ÷ FI); TME = AME +
5Nasco, Fort Atkinson, WI 53583.
6Fishers Scientific, Itasca, IL 60143.
(FEL ÷ FI); TMEn = AMEn + (FEL ÷ FI) – (8.22 × FNL ÷
7LECO Corp., St. Joseph, MI 49085.
FI), where EI is gross energy intake (kilocalories); EO is
8Parr Instrument Co., Moline, IL 61265.

3. 730 ADEOLA ET AL.
TABLE 2. Initial and final weights of ducks, Experiments 1 and 2
Item Initial weight Final weight Weight gain n
(g)
Experiment 1
–558b
Feed-deprived 3,726 3,168 4
–653a
Corn 3,746 3,093 4
–431c
Dehulled oats 3,742 3,311 4
–507b
Wheat 3,729 3,223 4
SEM 154 142 75
Experiment 2
Feed-deprived 3,767 3,281 –476 6
Corn 3,771 3,344 –427 6
Sorghum 3,747 3,265 –483 6
SEM 160 137 45
with no common superscript differ significantly (P ≤ 0.05).
a–cMeans
and dextrose was fed in two equal portions 6 h apart (at
gross energy output in the excreta (kilocalories); FI is
Hours 48 and 54, Table 1) and excreta collection was
feed intake (grams); ANR is apparent nitrogen retention
extended from a total of 48 to 54 h; thus, the
(grams) calculated as the difference between nitrogen
experimental period was increased from 96 to 102 h.
intake and nitrogen output; FEL is the fasting energy
This modification became necessary because in prelimi-
loss from the group of the feed-deprived ducks
nary experiments, ducks regurgitated generous portions
(kilocalories); and FNL is fasting nitrogen loss from the
of the test ingredients when 50 g was tube-fed at one
group of feed-deprived ducks (grams). Data from the
time. In an earlier report, Mohamed et al. (1986)
two experiments were subjected to the General Linear
suggested the necessity to feed the test materials in two
Models (GLM) procedures of SAS® (SAS Institute, 1990)
portions to avoid regurgitation. The collection technique
appropriate for a completely randomized design. Means
we developed was inspired in part by the technical note
were separated using the least significant difference test
published by Revington et al. (1991), in which specimen
(Steel and Torrie, 1980).
container caps with 3.5-cm center holes were secured to
the vents of chickens using cotton tapes tied up over the
RESULTS AND DISCUSSION back just posterior to the wings and around the base of
the tail; and rigid specimen containers were attached to
Surgical attachment of the modified retainer rings to serve as a collection vessel. This approach was unsuita-
the ducks was critical for collection of contaminant-free ble due to displacement of the specimen container cap
excreta and the accurate estimation of nitrogen and and container when the ducks assumed a squatting
energy output. The use of physical restraint and local position. With watery excreta, samples spilled from the
anesthetic during attachment of the retainer rings collection cups. For collection apparatus, we later
devised the use of materials from the Playtex™ baby
minimized stress and discomfort. The procedure was
done under the most hygienic condition possible and no nurser set. Surgical attachment of a collection apparatus
to the vent of the duck was considered a more suitable
infections or cellulitis were observed after surgical
method because it provided better security against
attachment. During the experiments, ducks adjusted
excreta loss. Cutting the plastic bottles to a length of 3
very well to the collection apparatus and there was no
cm below the threads on the bottle prevented undue
appearance of any discomfort or impaired mobility. The
tension on the sutures and displacement of the collection
ME assay used in the current experiments followed the
apparatus when the ducks assumed a squatting position
standard techniques devised by Sibbald (1976) and the
because the bottle did not make contact with the cage
modifications suggested by McNab and Blair (1988). The
floor. Excreta samples were stored in the same plastic
initial 48-h period of feed deprivation used in the
bags in which they were collected, thus preventing
current studies followed a report by McNab and Blair
losses that might occur during transfer to other
(1988) that the residue remaining in the digestive tract of
containers.
cockerels after 48 h was much less than after 24 h of feed
In Experiment 1, the analyzed nitrogen of corn,
deprivation (0.17 ± 0.08 vs 1.59 ± 0.56 g). In using the dehulled oats, and wheat were 1.12, 1.74, and 2.08%,
assay for ducks, it became necessary to modify the respectively, and gross energy of corn, dehulled oats,
techniques. We increased the amount of test ingredient and wheat were 3.991, 4.092, and 3.890 kcal/g, respec-
or dextrose tube-fed from 50 to 60 g, thus maintaining tively. In Experiment 2, analyzed nitrogen and gross
the feeding level at approximately 1.5 % body weight. energy of corn and sorghum were 1.12% and 3.984 kcal/
Feeding dextrose to birds from which endogenous losses g, and 1.76% and 4.181 kcal/g, respectively. The way
are collected decreases excessive weight loss and ducks were assigned to the fasting treatment and test
reduces the variability in endogenous losses (McNab ingredients ensured that initial weight was similar
across treatments in each experiment (Table 2). In
and Blair, 1988). During collection, the test ingredient

4. 731
METABOLIZABLE ENERGY ASSAYS FOR DUCKS
TABLE 3. Fasting losses of nitrogen1 and energy2 for feed- kcal/54 h observed in Experiments 1 and 2, respectively.
deprived ducks, Experiments 1 and 23
Nitrogen retention was higher (P < 0.05) in ducks that
were fed wheat than in those fed dehulled oats, which in
Item Mean SD Range
turn was higher (P < 0.05) than in those fed corn in
Experiment 1
Experiment 1 (Table 4). In the second experiment,
Fasting losses of
Nitrogen 292 112 142 to 444 nitrogen retention was lower (P < 0.05) in ducks fed
Energy 12.12 3.63 9.36 to 18.74
corn than in those fed sorghum. The differences in
Experiment 2
nitrogen retention presumably are reflective of the
Fasting losses of
nitrogen intake. Energy voided in the excreta was not
Nitrogen 461 326 258 to 1,139
Energy 22.26 2.84 17.59 to 28.05 different across treatments in either experiment.
In Experiment 1, the AME, AMEn, TME, and TMEn
1Milligramsper duck per 54 h.
for corn and wheat were similar to (P > 0.05) but lower
2Kiloocalories
per duck per 54 h.
than (P < 0.05) those of dehulled oats (Table 5). Corn
3Mean weights (initial, final, and loss) are indicated for feed-
deprived ducks in Table 2. and sorghum had similar energy values as determined
in Experiment 2. The NRC (1994) TMEn value for corn in
cockerel assays is 3.470 kcal/g, which lies in the range of
3.407 and 3.517 kcal/g obtained for corn in Experiments
Experiment 1, ducks that were fed 60 g of corn lost more 1 and 2, respectively. The TMEn values from ducks
(P < 0.05) weight than either the feed-deprived or determined in the current experiments vs NRC (1994)
wheat-fed ducks. Ducks that received dehulled oats lost values from cockerel assays for dehulled oats, wheat,
the least (P < 0.05) weight. In the second experiment, and sorghum experiments were 3.625 vs 2.625 (hulled
there was no difference in weight loss across treatments, oats), 3.312 vs 3.167, and 3.670 vs 3.376 kcal/g,
with ducks losing an average of 462 g over the respectively. Thus, the use of these values in formulating
102-h experimental period (Table 2). When returned to duck diets would make dehulled oats, wheat, and
full feed after the 102-h experiment, ducks regained all sorghum competitive in replacing corn, and values from
the weight lost within 7 d in both experiments. chicken AME assays may not be appropriate for use in
Although different groups of ducks were used in both of formulating duck diets.
the experiments reported here, based on our experience Correction of TME for nitrogen resulted in a 2 to 5%
in subsequent studies, the ducks could be used repeat- reduction in TME values of ingredients examined in
edly after recovery from lost weight without any both experiments, an observation similar to the 2 to 4%
apparent problems or loss of retainer rings sutured to reduction reported by McNab and Blair (1988) in TME of
the vents. The fasting losses of energy and nitrogen used ingredients for cockerels. Furthermore, the TMEn values
in calculating TME and TMEn were much higher in obtained were higher than the AMEn values, which
Experiment 2 than in Experiment 1 (Table 3). Fasting agrees with previous reports of 9 to 18% higher TME
losses of nitrogen and energy are only reasonably than AME in a variety of feed ingredients (Sibbald and
approximate and will vary from time to time and from Price, 1977; Baidoo et al., 1991).
bird to bird (McNab and Blair, 1988). In experiments The tube-feeding and excreta collection methods
with adult cockerels, fasting energy losses of between 14 described in this communication offer means of pre-
and 21 kcal/48 h were reported (McNab and Blair, 1988; cisely feeding known amounts of ingredients and
Yalcin and Onol, 1994), which are similar to 12 and 22 accurately collecting contaminant-free voided excreta
TABLE 4. Nitrogen and energy balances of ducks, Experiments 1 and 21
Nitrogen Nitrogen Nitrogen Energy Energy
Item intake output retention intake output n
(mg) (kcal)
Experiment 1
216c
Corn 675 460 239.18 42.69 4
573b
Dehulled oats 1,051 477 245.63 33.10 4
884a
Wheat 1,316 431 233.21 36.96 4
SEM 62 62 4.83
Experiment 2
Corn 671 524 148 239.13 44.86 6
Sorghum 1,048 546 503 250.78 45.34 6
SEM 74 74* 5.60
a,b,cMeans
in the same column and experiment with no common superscript differ significantly (P < 0.05).
1Mean weights (initial, final, and loss) are indicated for ducks fed test ingredients in Table 2.
*Treatment effect significant at P < 0.05.

5. 732 ADEOLA ET AL.
TABLE 5. The AME, AMEn, TME, and TMEn of ingredients, Experiments 1 and 2
Item AME AMEn TME TMEn n
(kcal/kg)
Experiment 1
3.275b 3.245b 3.477b 3.407b
Corn 4
3.542a 3.464a 3.744a 3.625a
Dehulled oats 4
3.271b 3.150b 3.473b 3.312b
Wheat 4
SEM 0.080 0.073 0.080 0.073
Experiment 2
Corn 3.230 3.210 3.600 3.517 6
Sorghum 3.432 3.363 3.802 3.670 6
SEM 0.093 0.084 0.093 0.084
a,bMeans in the same column and experiment with no common superscript differ significantly (P < 0.05.
that are extremely vital for obtaining reliable values Mohamed, K., M. Larbier, and B. Leclercq, 1986. A compara-
tive study of the digestibility of soybean and cottonseed
from ME assays. The technique provides a viable
amino acids in domestic chicks and Muscovy ducklings.
alternative to pan collection.
Ann Zootech. 35:79–86.
National Research Council, 1994. Nutrient Requirements of
Poultry. 9th rev. ed. National Academy Press, Washing-
ACKNOWLEDGMENTS
ton, DC.
Revington, W. H., N. Acar, and E. T. Moran, Jr., 1991. Research
The valuable technical assistance provided by Charles
note: Cup versus tray excreta collections in metabolizable
Thomas and Brian Ford, and the donation of ducks by
energy assays. Poultry Sci. 70:1265–1268.
Maple Leaf Farms, Milford, IN 46542 are thankfully SAS Institute, 1990. SAS® User’s Guide: Version 6. 4th ed. SAS
acknowledged. Institute Inc., Cary, NC.
Sibbald, I. R., 1976. A bioassay for true metabolizable energy in
feedstuffs. Poultry Sci. 55:303–308.
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McNab, J. M., and J. C. Blair, 1988. Modified assay for true and Hill Book Co., New York, NY.
apparent metabolizable energy based on tube feeding. Br. Yalcin, S., and A. G. Onol, 1994. True metabolizable energy
Poult. Sci. 29:697–707. values of some feedings. Br. Poult. Sci. 29:119–122.