J APPL POULT RES 2008. 17:540-544. doi:10.3382/japr.2008-00026
© 2008 Poultry Science Association
Comparison of Metabolic Energy Content of Organic Cereal Grains for Chickens and Turkeys
J. P. Jacob1,
S. L. Noll and
J. A. Brannon
University of Minnesota, Department of Animal Science, 1364 Eckles Ave., St. Paul 55108
1 Corresponding author: jacquie.jacob{at}uky.edu
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SUMMARY
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Although there is an extensive database on the nutrient content of conventionally produced feedstuffs, there is very little published research on the nutrient content of feedstuffs that are organically grown. Industrial and organic crop production differ in both crop and soil management. There are data to suggest that these differences may result in differences in the nutrient content of organic grown feedstuffs. The purpose of this study was to determine the ME content of organically grown amaranth, buckwheat, white corn, yellow corn, and wheat samples obtained from the University of Minnesota’s organic research farm. Both chickens and turkeys were used in the assays to compare the ME content for these 2 species. The TMEn content, on an as-fed basis, of amaranth, buckwheat, yellow corn, white corn, and wheat for chickens were found to be 3,146, 3,072, 3,603, 3,324, and 3,592 kcal/kg, respectively. The TMEn content of the same samples, on an as-fed basis, determined with turkeys were found to be 2,748, 2,227, 2,810, 2,757, and 2,959 kcal/kg, respectively. True ME content of the organically grown feed ingredients was found to be greater when chickens were used in the bioassay as compared with turkeys and differed significantly from published values for the same cereals grown using conventional means.
Key Words: organic grain • metabolizable energy • chicken • turkey
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DESCRIPTION OF THE PROBLEM
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Organic farming is one of the fastest growing segments of US agriculture, with a 111% increase in certified organic farmland from 2002 to 2005 [1]. Overall, organic poultry production showed a 119% increase during this same time period. As the market for organic poultry grows, the need for organic feedstuffs will also grow.
The composition of a given feedstuff may vary widely due to differences in climate, soil conditions, maturity, cultivar, management, and processing factors [2]. Industrial crop production typically includes commercial fertilizers and plant protection products. Most recently, industrial crop production has started using global positioning systems to more precisely add commercial fertilizer to the crop land. These practices minimize the differences in nutrient content of feedstuffs within and between farms. Organic crop production, on the other hand, relies on alternative management practices including crop rotation, soil management, and the use of organic fertilizers. It is generally assumed that the nutrient content and variation of organically grown feedstuffs are the same as for industrially grown crops, but with differences in crop and soil management between the 2 systems, this may not be the case.
When formulating poultry diets, it is important to know the energy content of the feed ingredients being used, especially those added with the main intention of supplying dietary energy. True ME is a common method used to assess the energy content of feed ingredients. When formulating diets for nonchicken poultry species, TME values determined using chickens are commonly used because there are limited data available particular to these alternative species. King et al. [3] showed that the TMEn values taken from chicken bioassays were not sufficient for use in formulating diets for ducks. Specifically they showed that the TMEn values for rice grains given in NRC [4] tables are less than those obtained when using ducks in the assay. Similarly, Cilliers et al. [5] showed that ostriches are capable of digesting feedstuffs, especially those high in fiber, more efficiently than chickens, indicating that energy values determined using chickens underestimate the available energy for ostriches.
Mossab et al. [6] showed that at an early age turkeys use fats, especially saturated fats, more efficiently than young chickens. In addition, fat utilization was not affected by age in turkeys, but increased greatly with the age of young chickens. This would suggest that turkeys have an earlier and greater maturation of the digestive system, especially for fat utilization, than chickens. As such, it would be best to use a separate set of energy values for fats, and perhaps other feedstuffs, when formulating turkey diets. Plavnik et al. [7] demonstrated that in both chickens and turkeys the growth and feed efficiency responses to energy supplied by fat were indistinguishable from those of carbohydrates.
Other researchers have also shown that the TMEn of feed ingredients determined using turkeys were different from TMEn determined using chickens. For example, Leeson et al. [8] showed that the TMEn of corn was 1.2% greater for poults than for 13-d-old chicks. Similarly, they demonstrated that the TMEn of oats was 8% greater for poults. Conversely, Sibbald [9] found that the TMEn for corn was 1% less in turkeys, whereas the TMEn for wheat bran was 3% greater.
There is an extensive database on the nutrient content of conventionally produced feed-stuffs; however, there is very little published research on the nutrient content of organically grown feedstuffs. The purpose of this study was to compare the available energy of organically grown amaranth (Amaranthus caudatus), buckwheat (Fagopyrum sagittatum), corn (Zea mays indenata), and wheat (Triticum durum) for chickens and turkeys.
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MATERIALS AND METHODS
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Organically grown amaranth, buckwheat, white corn, yellow corn, and wheat samples were obtained from the Southwest Research and Outreach Center of the University of Minnesota in Litchfield. All the samples were grown on the center’s organic farm. All but the amaranth samples were ground for TMEn determination. Amaranth seeds are extremely small and durable, so grinding them is extremely difficult in a commercial feed mill. Consequently, they were not ground in the TMEn determinations in this study.
The TMEn bioassays of these feed ingredients were determined for chickens and turkeys using the method developed by Sibbald [10]. For the chicken assays, adult Hy-Line W-36 Leghorn males were used. For the turkey assays, female turkeys (Large White, Nicholas) 6 to 8 wk of age and with a target weight of 2.5 kg were used.
Test birds were housed in individual cages with excreta collection trays underneath them. In each assay, the birds were fasted for 24 h to clear their digestive tracts. The birds were supplied water ad libitum and continuous light. The room temperature was set at 70°F. For each assay, 30 g of the test ingredient (organically grown amaranth, buckwheat, white corn, yellow corn, or wheat) was tube-fed to 8 birds, and an additional 8 birds were fasted throughout the assay to determine endogenous N and energy secretions. After 48 h, the trays were removed from the cages and the excreta collected and frozen for future analyses.
Each excreta sample was freeze-dried and ground before analysis. The feed ingredients and excreta samples were analyzed for DM, CP, crude fat, NDF, ADF, and gross energy (GE) content. Gross energy was determined using a Parr 1281 Bomb Calorimeter [11], whereas CP was determined using a Leco FP428 Nitrogen Analyzer [12].
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RESULTS AND DISCUSSION
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The results of this study are shown in Tables 1
and 2. Table 1 shows the nutrient content of the organically grown feed ingredients. All the values are on an as-fed basis. Dry matter was similar for the 5 samples. Yellow corn had the least CP content as well as the least GE. Similarly, amaranth had the greatest CP and GE content. Buckwheat had the greatest fiber, whereas wheat had the least fat content.
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Table 2. Nitrogen-corrected TMEn, on an as-fed basis, of the organically grown cereal grains as determined with chickens and turkeys
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Table 2
shows the TMEn content of the organic feedstuffs as determined with chickens and turkeys and compared with NRC values [4]. The TMEn content of the samples were greater when chickens were used in the assay. On average, the TMEn determined using chickens were 19.4% greater than those determined with turkeys. The NRC [4] did not report any TMEn values for amaranth. For the remaining samples, the TMEn values determined with chickens were greater than the published values, whereas those determined with turkeys were less. This would indicate that there is a need for further research, using a broad base of samples, to determine the variability in TMEn values for organically grown feedstuffs. Such a database of TMEn content is important when formulating poultry diets.
Although amaranth and buckwheat had the greatest GE content of the grains evaluated, they had the least TMEn for both chickens and turkeys. Amaranth is a high protein grain with a well-balanced amino acid profile. The high GE content is because of its high fat content. Feeding experiments have indicated that amaranth seeds contain factor(s) that suppress feed intake and inhibit growth [13]. One of these factors is believed to be the fiber content. Crude fiber content reported in the literature varies considerably, ranging from 3 to 6%. The color of the seeds may be an indicator of the digestible fiber content. Pale seeds are reported to contain about 8% dietary fiber, whereas the black seeds contain about twice as much [13]. The amaranth seeds used in this study were pale in color. The lesser TMEn value for amaranth may be due to poor digestion of the whole seeds. High fiber diets have resulted in increased nitrogen excretion in rats and a large variability in TMEn [14, 15], and this may account for the lesser TMEn for buckwheat, which had the greatest fiber content of the samples studied.
The inclusion of buckwheat in organic poultry diets has become popular in the Midwest of the United States because of increased availability. Buckwheat fits well into a crop rotation for organic production. The protein content of buckwheat is highly variable, ranging from 7 to 21% depending on the cultivar and environmental factors during growth, although the most commonly grown cultivars yield 11 to 15% protein on a whole-seed basis [16]. High protein cultivars of buckwheat have about twice the level of protein of yellow corn but 15 to 30% less available energy. Such cultivars are potential alternatives to yellow corn in organic poultry diets. The buckwheat sample used in this study had 15.2% CP on an as-fed basis, which was more than twice the level of protein in the yellow corn sample. Although the buckwheat and yellow corn samples used in this study had similar GE content (4,106 and 3,956 kcal/kg, respectively), the buckwheat sample had a ~15% less TMEn content than the yellow corn.
The wheat sample used in this study had a similar protein content to the buckwheat sample (16.9 vs. 15.2% CP), but its greater TMEn content (3,592 vs. 3,072 kcal/kg for chickens and 2,959 vs. 2,227 kcal/kg for turkeys) would make it a more desirable substitute for yellow corn in organic poultry diets than buckwheat. The current prices of the various ingredients would be the main factor in determining which cereal to use in an organic broiler diet.
The 2 types of corn used in this study were white and yellow corn. Both are similar in carbohydrate content, but yellow corn is more commonly used in poultry feeds because it is a source of xanthophylls for broiler skin and egg yolk color. The DM and GE content of the 2 corn samples in this study were similar. The TMEn contents of the 2 samples were similar in turkeys, but the TMEn of yellow corn was considerably greater than that of white corn when chickens were used in the bioassay. The TMEn of the yellow corn was only 1.8% greater when turkeys were used in the bioassay but 7.7% greater when roosters were used. Although white corn was found to have greater protein content, the lesser TMEn for chickens discourages its use in poultry diets.
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CONCLUSIONS AND APPLICATIONS
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- Based on determined TMEn values, chickens are better able to utilize the energy in organically grown buckwheat and amaranth than turkeys. Chickens were able to use 75% of the GE in buckwheat and amaranth, whereas turkeys were only able to use 65% of the GE in amaranth and 54% of the GE of buckwheat.
- The TMEn values obtained for the organically grown grains in this study differed significantly from values reported in NRC. There was no value for amaranth to use as a comparison, but the TMEn for buckwheat was greater than NRC values when chickens were used but less when turkeys were used. Similar results were obtained for corn and wheat.
- The results of this study demonstrate the need for further research on the available energy content of organic versus conventional feedstuffs.
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ACKNOWLEDGMENTS
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This research was partially funded by a grant from USDA/Cooperative State Research, Education, and Extension Service.
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REFERENCES AND NOTES
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- United States Department of Agriculture’s Economic Research Service. 2006. Data sets: Organic production. http://www.ers.usda.gov/Data/Organic/index.htm Last accessed July 2008.
- van Keulen, H., and W. Stol. 1991. Quantitative aspects of nitrogen nutrition in crops. Fert. Res. 27:151–160.[CrossRef]
- King, D., D. Ragland, and O. Adeola. 1997. Apparent and true metabolizable energy values of feedstuffs for ducks. Poult. Sci. 76:1418–1423.[Abstract/Free Full Text]
- National Research Council. 1994. Nutrient Requirements of Poultry. 9th ed. Natl. Acad. Press, Washington, DC.
- Cilliers, S. C., J. Sales, J. P. Hayes, A. Chwalibog, and J. J. Du Preez. 1999. Comparison of metabolizable energy values of different foodstuffs determined in ostriches and poultry. Br. Poult. Sci. 40:491–494.[CrossRef][Web of Science][Medline]
- Mossab, A., J. M. Hallouis, and M. Lessire. 2000. Utilization of soybean oil and tallow in young turkeys compared with young chickens. Poult. Sci. 79:1326–1331.[Abstract/Free Full Text]
- Plavnik, I., E. Wax, D. Sklan, I. Bartov, and S. Hurwitz. 1997. The response of broiler chickens and turkey poults to dietary energy supplied either by fat or carbohydrates. Poult. Sci. 76:1000–1005.[Abstract/Free Full Text]
- Leeson, S., K. N. Boorman, D. Lewis, and D. H. Shrimpton. 1974. Metabolizable energy studies with turkeys: Metabolizable energy of dietary ingredients. Br. Poult. Sci. 15:185–189.
- Sibbald, I. R. 1976. The true metabolizable energy values of several feedingstuffs measured with roosters, laying hens, turkeys and broiler hens. Poult. Sci. 55:1459–1463.[Web of Science]
- Sibbald, I. R. 1976. A bioassay for true metabolizable energy in feedingstuffs. Poult. Sci. 55:303–308.[Web of Science][Medline]
- Parr 1281 Bomb Calorimeter. Parr Instrument Company, Moline, IL (http://www.parrinst.com/).
- Leco, F. P. 428 Nitrogen Analyzer. Leco Corporation, St. Joseph, MI (http://www.leco.com/).
- Pedersen, B., K. E. Back Knudsen, and B. O. Eggum. 1990. The nutritive value of amaranth grain (Amaranthus caudatus) 3. Energy and fiber content of raw and processed grain. Plant Foods Hum. Nutr. 40:61–71.[CrossRef][Web of Science][Medline]
- Beames, R. M., and B. O. Eggum. 1981. The effect of type and level of protein, fibre, and starch on nitrogen excretion patterns in rats. Br. J. Nutr. 46:301–313.[CrossRef][Web of Science][Medline]
- Sibbald, I. R. 1979. The effect and duration of the excreta collection period on the true metabolizable energy values of feedingstuffs with slow rate of passage. Poult. Sci. 58:896–899.[Web of Science]
- Campbell, C. G. 1997. Buckwheat. International Plant Genetic Resources Institute (IPGRI), Manitoba, Canada.
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SUMMARY
DESCRIPTION OF THE PROBLEM
