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METABOLISM AND NUTRITION: Research Notes |
Department of Animal Sciences, The Ohio State University, Columbus 43210
1 Corresponding author: latshaw.1{at}osu.edu
| ABSTRACT |
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Key Words: apparent metabolizable energy true metabolizable energy rooster
| INTRODUCTION |
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A different procedure for measuring ME was developed by Sibbald (1976, 1979). Mature White Leghorn roosters were fasted for 24 h. One group of roosters was fasted for an additional 48 h, and excreta were collected during this time and contained the metabolic and endogenous losses. Another group was force-fed approximately 30 g of the test ingredient, and then excreta were collected for 48 h. To adjust for the metabolic and endogenous losses in the excreta of the fed roosters, energy losses from the fasted roosters were used as a correction factor. The resulting ME values, TMEn, were higher than those from the AMEn. This procedure made it possible to determine energy in a feed ingredient in a week or less and required fewer animals and laboratory work.
Several modifications to the second procedure have been reported. One was to train adult roosters to eat their daily feed in about an hour instead of force feeding (Farrell, 1978). The excreta collection was for 24 h. Another modification was to remove the ceca from roosters before using them for force-feeding ingredients (Parsons, 1984). Although the modification was initially used for studying amino acid digestibility, the excreta from the same assay can be used for determination of ME and amino acid digestibility. Another modification was to decrease body catabolism during the extended fast by providing an energy source, such as glucose, for the fasted roosters (McNab and Blair, 1988). The result was a ME value that was between AME and TME and was changed by the amount of glucose provided.
The objectives of our research were to determine how removal of the ceca and adjusting for nitrogen balance would affect the value assigned to the ME of a feed.
| MATERIALS AND METHODS |
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Excreta samples were dried in a room heated to 27°C, where the air was circulated by fans. Dried samples were ground with a mortar and pestle. The energy content of feed and excreta samples was determined with an adiabatic calorimeter (Parr Instrument Company, Moline, IL). Nitrogen content of feed and excreta samples was determined with a nitrogen analyzer (Perkin Elmer, Wellesley, MA).
The energy content of the samples was calculated as follows:
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where A = total feed energy; B = total excreta energy of fed roosters; C = total excreta energy of fasted roosters; and D = 8.22 x nitrogen balance (g).
Results were statistically compared using Students t-test. Probabilities of the comparisons between roosters are provided.
| RESULTS |
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| DISCUSSION |
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Results from this research show that intact roosters may be preferable to cecectomized roosters for determining ME. The undigested residue from the test diet was larger from the cecetomized roosters than from the intact roosters (Table 2
). This caused total energy and nitrogen losses to be larger from these roosters, which in turn caused lower values for all of the ME calculated in Table 3
. Similar results were reported previously when ingredient digestibility by intact and cecectomized roosters was compared (Parsons et al., 2000). Birds in commercial flocks are not cecectomized, so using cecectomized roosters for energy assays may understate the energy available to poultry in commercial flocks. If ME were determined by ileal digestibility (Payne et al., 1968; Ravindran et al., 1999), the energy content would also be understated because the residue from the small intestine was not digested by microorganisms in the hindgut.
Providing only a limited amount of feed for the assay may overstate the effect of cecectomy. In our experiment, only 28 g of feed was provided in 48 h. Assuming the roosters weighed 2.25 kg and that they needed 100 kcal of ME/kg/d (MacLeod and Jewitt, 1988), they would have needed more than 125 g of feed in 48 h to maintain energy balance. Whether the microorganisms in the ceca would be able to digest the residue from that amount of feed as completely as from the 28 g that was fed cannot be answered from our results.
Received for publication March 21, 2007. Accepted for publication September 13, 2007.
| REFERENCES |
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Farrell, D. J. 1978. Rapid determination of metabolisable energy of foods using cockerels. Br. Poult. Sci. 19:303–308.[CrossRef][Web of Science]
Hill, F. W., and D. L. Anderson. 1958. Comparison of metabolizable energy and productive energy determinations with growing chicks. J. Nutr. 64:587–603.
MacLeod, M. G., and T. R. Jewitt. 1988. Maintenance energy requirements of laying hens: A comparison of measurements made by two methods based on indirect calorimetry. Br. Poult. Sci. 29:63–71.[CrossRef][Web of Science][Medline]
McNab, J. M., and J. C. Blair. 1988. Modified assay for true and apparent metabolisable energy based on tube feeding. Br. Poult. Sci. 29:697–707.[CrossRef][Web of Science][Medline]
Parsons, C. M. 1984. Influence of caecetomy and source of dietary fibre or starch on excetion of endogenous amino acids by laying hens. Br. J. Nutr. 51:541–548.[CrossRef][Web of Science][Medline]
Parsons, C. M., Y. Zhang, and M. Araba. 2000. Nutritional evaluation of soybean meals varying in oligosaccharide content. Poult. Sci. 79:1127–1131.
Payne, W. L., G. F. Combs, R. R. Kiefer, and D. G. Snyder. 1968. Investigation of protein quality—Ileal recovery of amino acids. Fed. Proc. 27:1199–1203.[Web of Science][Medline]
Ravindran, V., L. I. Hew, G. Ravindran, and W. L. Bryden. 1999. A comparison of ileal digesta and excreta analysis for the determination of amino acid digestibility in food ingredients for poultry. Br. Poult. Sci. 40:266–274.[CrossRef][Web of Science][Medline]
Sibbald, I. R. 1976. A bioassay for true metabolizable energy in feedingstuffs. Poult. Sci. 55:303–308.[Web of Science][Medline]
Sibbald, I. R. 1979. Effects of level of feed input, dilution of test material and duration of excreta collection on true metabolizable energy values. Poult. Sci. 58:1325–1329.[Web of Science]
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