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  1. 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. 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. 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. 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. 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. REFERENCES Sibbald, I. R., and K. Price, 1977. True and apparent metabolizable energy values for poultry of Canadian Baidoo, S. K., A. Shires, and A. R. Robblee, 1991. Effect of wheats and oats measured by bioassay and predicted from kernel density on the apparent and true metabolizable physical and chemical data. Can. J. Anim. Sci. 57:365–374. energy value of corn for chickens. Poultry Sci. 70: Steel, R.G.D., and J. H. Torrie, 1980. Principles and Procedures 2102–2107. of Statistics. A Biometrical Approach. 2nd ed. McGraw- 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.