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J APPL POULT RES 2007. 16:642-651. doi:10.3382/japr.2007-00007
© 2007 Poultry Science Association
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Field Reports

Nutrient Content of Organically Grown Feedstuffs

J. P. Jacob1

University of Minnesota, 1364 Eckles Ave., St. Paul 55108

Correspondence: 1 Corresponding author: jacob150{at}umn.edu


   SUMMARY
TOP
 SUMMARY
DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Many smaller farms in the United States are switching to organic crop production to remain competitive with industrial agriculture. In doing so, they are cultivating crops not traditionally grown in the area. Organically grown corn, wheat, barley, oats, soybeans, field peas, buckwheat, and flaxseed samples were obtained from producers throughout the Midwest. The nutrient content of the organically grown feedstuffs was compared with published values for industrially grown counterparts. The nutrient content of a given feedstuff has been shown to vary because of differences in climate, soil conditions, maturity, cultivar, management, and processing factors. As an emerging industry, organic crop production practices vary considerably from farm to farm. As a result, there is considerable variation in the nutrient content of organically grown feedstuffs, as noted with the samples analyzed. This variation will affect the formulation of organic livestock feeds and demonstrates the need to develop a database of the nutrient content of organically grown feedstuffs.

Key Words: ingredient • nutrient • organic


   DESCRIPTION OF PROBLEM
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Although it still remains a minor component of US agriculture, organic farming has been one of the fastest growing segments, with an increase of 111% in total certified organic farmland from 2002 to 2005 [1]. During this same time period, overall organic poultry production has shown similar growth, with an increase of 119%. Organic table eggs and chicken meat represent the major increases in poultry production, with 130 and 243%, respectively [1]. As the market for organic poultry grows, the need for organic feedstuffs will also grow.

In organic production, crop rotation is a major tool used to control pests and disease [2, 3]. Crops being suggested by the organic community for inclusion in crop rotations include buckwheat, sorghum, millet, rye, hulless or naked oats, flax, and field peas, crops not routinely used in poultry feeds in the United States [4]. Organic soybeans are also available and can be included in poultry diets roasted or as an expelled meal, neither of which is routinely used in commercial poultry feeds, in which solvent-extracted meal is more common.

The composition of a given feedstuff may vary widely because of differences in climate, soil conditions, maturity, cultivar, and management and processing factors [5]. Industrial crop production typically includes commercial fertilizers and plant protection products. Most recently, industrial crop producers have started making use of global positioning systems to more precisely add commercial fertilizer to the cropland. These practices minimize the differences within and among farms. Organic crop production, on the other hand, relies on alternative management practices, including crop rotation, soil management, and the use of organic fertilizers. The nutrient content and variation of organically grown feedstuffs is generally assumed to be the same as for industrially grown crops, but because of the differences in crop and soil management between the 2 systems, this may not be the case.

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 organically grown feedstuffs. The purpose of this research was to evaluate the nutrient content of organically grown feedstuffs, looking particularly at the variability in nutrient content. Particular attention was paid to flax samples, because flax is added to poultry diets to increase the n-3 levels in the eggs or meat produced [6, 7, 8, 9]. There are field reports in both Canada [10] and the United States [4] of failures to achieve a consistent year-round level of n-3 in poultry products. It is possible that variations in the level of n-3 fatty acids in the flaxseed could account for this failure.


   MATERIALS AND METHODS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Organically grown corn, wheat, barley, oats, soybeans, field peas, buckwheat, and flaxseed samples were obtained from producers throughout the Midwest. All the samples were organically grown, but were not necessarily certified organic. Some were classified as transitional, because crops have to be grown on a particular field for 3 yr before they can be certified as organic. Very little additional information regarding the farm was provided. Six corn, 9 wheat, 5 barley, 5 oat, 7 whole soybean, 3 soybean meal, 8 field pea, 7 buckwheat, and 4 flax samples were contributed from various farms in the region. In addition, 57 flax samples were obtained from random sections of a large organic crop research plot at the Southern Research and Outreach Center at Waseca, Minnesota.

All samples were analyzed for DM, CP, ash, minerals, NDF, and ADF at the University of Minnesota by using routine procedures. Crude protein was determined with a Leco FP428 Nitrogen Analyzer [11]. Neutral detergent fiber and ADF were determined by the methods developed by Van Soest et al. [12]. Crude fat as well as amino acid and fatty acid profiles were determined by the University of Missouri-Columbia Experiment Station Chemical Laboratories [13] by using standard methods.


   RESULTS AND DISCUSSION
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 
Flax
Flax has received increased attention in the last few years, especially for poultry producers supplying niche markets. As previously indicated, addition of flaxseed to the diet of laying hens, typically at the level of 8 to 10%, has been shown to increase the n-3 content of the eggs produced [6, 7, 8, 9]. Flax oil contains approximately 50% linolenic acid (18:3n-3) [14]. Linolenic acid, and its desaturation products docosahexaenoic acid and eicosapentaenoic acid, have been shown to be important in human health [15, 16, 17, 18]. As a result, there is a niche market for n-3-enriched eggs and chicken.

The DM, CP, and amino acid profiles of the flax samples are shown in Table 1Go. The samples are separated into the 57 random samples obtained from a single field of flax and the 4 samples obtained from individual producers. The samples were compared with the data presented in the latest Feedstuffs 2007 Reference Issue and Buyers Guide [19]. The average CP contents for both groups of samples (20.8 and 21.8%, respectively) were similar but slightly lower than that reported for industrially produced flax (22.0%). The levels of Cys, His, Leu, Phe, and Thr were similar for all groups. However, the levels of Arg, Ile, Lys, and Val were lower, and the Trp and Met levels were greater for the organically grown flax samples.


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  		Table 1. Nutrient content of flaxseed samples—DM, CP, and amino acid profile
 
The crude fat and fatty acid profiles of the flax samples are shown in Table 2Go. Very few studies have been published in which the fatty acid content of flaxseed was determined. The results from our study were compared with those obtained from samples collected from commercial feed mills in Canada, and were assumed not to have been organically grown [10]. Because flaxseed is added to poultry diets to increase the n-3 levels of the eggs or meat produced, particular attention was paid to these fatty acids. As previously indicated, the main n-3 fatty acid in flax is linolenic acid. The level of linolenic acid in the flax from the 2 sources of organically grown flax were similar to those reported for conventionally produced flax, approximately 50% of the fat present [14].


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  		Table 2. Fatty acid content of flaxseed samples
 
Because the crude fat content of the organically grown flax samples varied considerably (23.5 to 45.0%), the data are also reported on an as-is basis (Table 3Go). The total level of n-3 fatty acids varied considerably, from 10.4 to 24.2%. This large variation may be the reason producers are unable to maintain n-3 levels in flax-supplemented organic eggs. By comparison, however, Bean and Leeson [14] analyzed 23 samples of flaxseed collected from commercial feed mills throughout Ontario, Canada. They concluded that it is unlikely that the source of flaxseed is a major factor associated with the failure to maintain adequate n-3 levels in enriched eggs. However, the samples collected were not organically grown. Because the inability to maintain enriched levels occurs with hens fed either organically or industrially produced eggs, additional research is required to understand the cause.


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  		Table 3. Fatty acid content of flaxseed samples, on an as-is basis
 
The great variation in n-3 fatty acid levels in the organically grown samples may be due to a variety of management factors, which vary considerably among organic producers. The nutrient content of crops is known to be affected by genetics, weather (especially rainfall), fertilizer management, crop rotation, background soil characteristics, and other agronomic practices [20, 21]. These agronomic practices can differ considerably between industrial and organic crop production.

Cereals
The DM, CP, and amino acid profiles of the corn and wheat samples are shown in Table 4Go. The values obtained in this study were compared with those reported in the Feedstuffs 2007 Reference Issue and Buyers Guide for hard, winter wheat [19]. The CP contents of the organically grown samples was slightly lower than those for the industrially grown samples (7.3 vs. 7.5% for corn and 13.1 vs. 13.5% for wheat). For the organically grown corn samples, the amino acid levels were comparable to the industrially grown samples, with the exception of Lys levels, which were greater. The organically grown wheat samples had greater Arg, Cys, His, and Thr levels. The difference was greatest for the levels of His. Levels of Ile, Leu, Phe, and Val were lower in the organically grown wheat samples. Again, it is important to note the considerable variation in the nutrient content of the organically grown feedstuffs. The CP content of the wheat samples, for example, varied from 9.5 to 15.4%. This is similar to reports in the literature indicating that the composition of wheat, especially the protein content, is usually more variable than that of other cereals and is believed to be due to variation in varieties and growing conditions [20, 21]. The growing conditions of the samples analyzed were not known but were expected to be different among farms.


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  		Table 4. Nutrient content of organically grown corn and wheat samples—DM, CP, and amino acid profile
 
The DM, CP, and amino acid profiles of the barley and oat samples are shown in Table 5Go. The values obtained in this study were compared with those reported in the Feedstuffs 2007 Reference Issue and Buyers Guide [19]. The average CP of the organically grown barley samples was similar to that reported in the literature (11.7 vs. 11.5%). The levels of amino acids were similar, except for Arg, which was greater in the organically grown samples (0.66 vs. 0.50%). The average CP of the organically grown oat samples was slightly greater than that reported in the literature (12.3 vs. 11.0%). The levels of Cys, His, Lys, and Thr were greater and the levels of Ile and Trp were lower for the organically grown oat samples.


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  		Table 5. Nutrient content of organically grown barley and oat samples—DM, CP, and amino acid profile
 
There was considerable variation in the protein content of the organic barley samples, ranging from 9.9 to 15.7%. In contrast, the variation in the organic oat samples was not as large (10.1 to 13.7%). The Lys levels in the organic barley samples showed the most variation, ranging from 0.39 to 0.74%, nearly a 2-fold difference.

Protein Sources
The DM, CP, and amino acid profiles of the raw soybean and expeller-extracted soybean meal samples are shown in Table 6Go. The values obtained in this study were compared with those reported in the Feedstuffs 2007 Reference Issue and Buyers Guide [19].


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  		Table 6. Nutrient content of organically grown raw soybean and expeller-extracted soybean meal samples—DM, CP and amino acid profile
 
Soybeans are an excellent source of protein in poultry diets. Although the average CP content of the organic soybeans was similar to the content of conventionally grown soybeans, there was considerable variation in the protein content of the organic soybeans (30.4 to 49.4%). Although the average Lys levels were similar for the organic and conventional samples, there was considerable variation in the levels in the organic samples (1.95 to 2.74%). The variation in protein and amino acid levels was not as great in the organic soybean meal (41.9 to 44.2% CP, 0.54 to 0.61% Met, and 2.5 to 2.8% Lys).

The DM, CP, and amino acid profiles of the field pea and buckwheat samples are shown in Table 7Go. The field pea values obtained in this study were compared with the 1994 values reported by the NRC [22], whereas the buckwheat values were compared with those reported in the Feedstuffs 2007 Reference Issue and Buyers Guide [19]. Although the Feedstuffs reference guide provides the most up-to-date information regarding the nutrient content of feed ingredients, it does not include field peas, so the NRC reference was used.


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  		Table 7. Nutrient content of organically grown field peas and buckwheat samples—DM, CP, and amino acid profile
 
Field peas are an alternative protein source for poultry diets. One of the major limitations to using field peas, however, is the low levels of sulfur amino acids. The average CP and Met levels for the organic field peas were similar to industrially grown field peas, but protein levels varied from 19.1 to 26.4%, with Met levels varying from 0.18 to 0.26% in the organic samples.

The inclusion of buckwheat in organic poultry diets has become popular in the Midwest. 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 [23]. The same variation in CP was observed with the organic buckwheat samples (10.8 to 13.5%). The Arg, Cys, His, Ile, Leu, Lys, Met, Phe, Thr, and Val levels were greater in the organic buckwheat samples, whereas the Trp levels were lower.

It is well known that the quality of the soil affects the crops grown on it [24]. Important soil quality factors are soil tilth, aeration, water, and the quantity and availability of minerals and other soil nutrients. Many organic farmers use a variety of fertilizers, such as composted manures and plant wastes, which break down slowly, providing nutrients over a longer period of time. Organic farmers also use crop rotation, seasonal cover cropping, and conservation tillage to maintain soil quality. In contrast, industrial crop producers primarily use synthetic fertilizers containing a few key nutrients necessary for plant growth and synthetic chemical pesticides to eliminate or control insects, weeds, and other pests. In a literature review, Worthington [25] concluded that there is a trend for greater nutrient content in organically grown crops, although in her comparison she looked primarily at vegetables. Organic fertilization was reported to produce crops with greater levels of ascorbic acid, lower levels of nitrates, and improved protein quality compared with conventionally grown crops.

In a later study, Worthington compared organically and conventionally grown cereals [26]. She reported less protein in organic cereal grains and speculated that this is a result of lower amounts of nitrogen in organically managed soils. The report by Bourn and Prescott [27] disagrees with the conclusions of Worthington [25, 26]. They concluded that, with the possible exception of nitrate content, there is no strong evidence that organic and conventional foods differ in concentrations of various nutrients. They also stated that very few well-controlled studies are capable of making a valid comparison between organic and conventional production.

The results of this study demonstrate the need for further research in the area of the nutrient content of organically grown feedstuffs for inclusion in animal feeds, especially for monogastrics such as poultry. Organic livestock producers need a database for use in on-farm feed production, as well as commercial feed mills that produce organic animal feeds.


   CONCLUSIONS AND APPLICATIONS
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
REFERENCES AND NOTES
 

  1. Overall, there are similarities in the average nutrient content of organic and industrial feedstuffs, but some major differences were noted, indicating a need for further research, with a larger sample base, to verify the differences observed.
  2. Organically grown feedstuffs can have wide variations in nutrient content that will affect the consistent formulation of organic livestock feeds. Although near-infrared spectroscopy would be a useful technology in helping organic feed mills deal with this variation, such technology is not available nationwide.


   ACKNOWLEDGMENTS
 
This project was funded by a grant from the USDA-Cooperative State Research, Education, and Extension Service (CSREES). The author would like to thank Jeanine Brannon, a technician at the University of Minnesota, Department of Animal Science, who assisted with the analyses in this project.


   REFERENCES AND NOTES
TOP
 SUMMARY
 DESCRIPTION OF PROBLEM
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSIONS AND APPLICATIONS
 REFERENCES AND NOTES
 

  1. USDA, Economic Research Service. 2006. Data sets: Organic production. Available: http://www.ers.usda.gov/Data/Organic/index.htm Accessed April 2, 2007.
  2. Foster, K. 1996. Organic crop production: Weed management. Saskatchewan Agriculture and Food Publication. Available: http://www.agr.gov.sk.ca/docs/organics/organicweed.asp Accessed April 2, 2007.
  3. Dyck, E., P. M. Porter, N. S. Eash, D. L. Allan, C. Fernholz, E. Saeger, and L. Nickel. 1999. Weed management for organic production systems in the northern corn belt. Page 263 in Agronomy Abstracts, Ann. Mtg. of the Am. Soc. Agron., Crop Sci. Soc. Am., and Soil Sci. Soc. Am., Salt Lake City, UT.
  4. Jacob, J. P. 2006. University of Minnesota, St. Paul. Personal communication.
  5. van Keulen, H., and W. Stol. 1991. Quantitative aspects of nitrogen nutrition in crops. Fertilizer Res. 27:151–160.[CrossRef]
  6. Caston, L., and S. Leeson. 1990. Research note: Dietary flax and egg composition. Poult. Sci. 69:1617–1620.[ISI]
  7. Scheideler, S. E., D. Jaroni, and G. Froning. 1998. Strain and age effects on egg composition from hens fed diets rich in n-3 fatty acids. Poult. Sci. 77:192–196.[Abstract/Free Full Text]
  8. Bean, L. D., and S. Leeson. 2003. Long-term effects of feeding flaxseed on performance and egg fatty acid composition of brown and white hens. Poult. Sci. 82:388–394.[Abstract/Free Full Text]
  9. Mazalli, M. R., D. E. Faria, D. Salvador, and D. T. Ito. 2004. A comparison of the feeding value of different sources of fat for laying hens: 2. Lipid, cholesterol, and vitamin E profiles of egg yolk. J. Appl. Poult. Res. 13:280–290.[Abstract/Free Full Text]
  10. Bean, L. D., and S. Leeson. 2002. Fatty acid profiles of 23 samples of flaxseed collected from commercial feed mills in Ontario in 2001. J. Appl. Poult. Res. 11:209–211.[Abstract/Free Full Text]
  11. Leco, F. P. 428 Nitrogen Analyzer. Leco Corporation, St. Joseph, MI (http://www.leco.com/).
  12. Van Soest, P. J., J. B. Robertson, and B. A. Lewis. 1991. Symposium: Carbohydrate methodology, metabolism and nutrition implications in dairy cattle. J. Dairy Sci. 74:3583–3597.[Abstract]
  13. Experiment Station Chemical Laboratories. University of Missouri-Columbia, Agriculture Building, Columbia, MO.
  14. Leeson, S., and J. D. Summers. 2005. Commercial Poultry Nutrition. 3rd ed. University Books, Guelph, Ontario, Canada.
  15. Temple, N. J. 1996. Dietary fats and coronary heart disease. Biomed. Pharmacother. 50:261–268.[CrossRef][Medline]
  16. Pandalai, P. K., M. J. Pilat, K. Yamazaki, H. Naik, and K. J. Pienta. 1996. The effects of omega-3 and omega-6 fatty acids on in vitro prostrate cancer growth. Anticancer Res. 16:815–820.[ISI][Medline]
  17. Rose, D. P. 1997. Dietary fatty acids and prevention of hormone-responsive cancer. Proc. Soc. Exp. Biol. Med. 216:224–233.[Abstract]
  18. Neuringer, M., G. J. Anderson, and W. E. Conner. 1998. The essentiality of {omega}-3 fatty acids for the development and function of the retina and brain. Annu. Rev. Nutr. 8:517–541.[CrossRef]
  19. Dale, N., and A. Batal. 2006. Ingredient analysis. In 2007 Reference Issue and Buyers Guide. Feedstuffs 78(38):16–23.
  20. Harris, H. C., J. R. McWilliam, and W. K. Mason. 1978. Influence of temperature on oil content and composition of sunflower seed. Aust. J. Ag. Res. 29:1203–1212.[CrossRef][ISI]
  21. Grant, C. A., R. B. Irvine, D. A. Derkson, D. L. McLaren, K. Buckley, M. Monreal, A. Moulin, R. Mohr, J. House, B. Marchylo, and N. Ames. 2001. Impact of organic production and reduced chemical inputs on soil nutrient depletion and the functional and nutritional quality of crops. Report of the Organic Agricultural Centre of Canada (OACC). Available: http://www.organicagcentre.ca/ResearchData-base/res_impact_org_prod.html Accessed Jan. 2007.
  22. NRC. 1994. Nutrient Requirements of Poultry. 9th ed. Natl. Acad. Press, Washington, DC.
  23. Campbell, C. G. 1997. Buckwheat. Int. Plant Genetic Res. Inst., Manitoba, Canada.
  24. Beeson, K. C., and G. Matrone. 1976. The soil factor in animal and human nutrition. Nutr. Clin. Nutr. 2:11–28.
  25. Worthington, V. 1998. Effect of agricultural methods on nutritional quality: A comparison of organic with conventional crops. Alt. Ther. 4:58–69.
  26. Worthington, V. 2001. Nutritional quality of organic versus conventional fruits, vegetables and grains. J. Alt. Compl. Med. 7:161–173.[CrossRef][ISI][Medline]
  27. Bourn, D., and J. Prescott. 2002. A comparison of the nutritional value, sensory qualities, and food safety of organically and conventionally produced foods. Crit. Rev. Food Sci. Nutr. 42:1–34.[CrossRef][ISI][Medline]




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