Winkler, L. R., Lyon, S. R. and Jones, S. S. Washington State University, Northwestern Washington Research & Extension Center, Mount Vernon, WA 98273
Oats (Avena sativa L.) and peas (Pisum sativum L.) both have track records as successful crops in the Puget Sound agricultural region. There is potential to use oats and peas to replace imported corn and soy in poultry diets, allowing Western Washington poultry producers to respond to consumer demand for local food at the same time as improving the environmental performance of agriculture and increasing regional self-sufficiency.
Projects at the Northwest Washington Research and Extension Center are (1) exploring the effect of hulless oats in layer rations on egg productivity and quality; and (2) evaluating the field performance and nutritional potential of a winter pea varieties and breeding lines. Both of these projects focus on the needs of organic production systems.
- Hulless oats
Studies have demonstrated that hulless oats (A. sativa subsp. nudisativa (Husnot.) Rod. et Sold.) can make a valuable nutritional contribution to poultry diets. Hulless oats have a high content of oil and therefore yield more energy than wheat (Macleod 2004). They also have a high protein content and a superior amino acid profile to corn (Maurice et al., 1984). In particular, hulless oats may offer higher levels than some other cereal grains of the sulfuric amino acids methionine and cysteine, which are low in most cereals and are a limiting amino acid for poultry (Farkhoy et al. 2012). Non-organic poultry producers supplement diets with synthetic methionine in order to protect bird health and maintain productivity, but this practice is strictly limited in organic production systems (Jacob 2013). If hulless oats can be demonstrated to improve methionine content of organic poultry diets relative to corn- and wheat-based feeds, they could be an important resource for organic producers.
A disadvantage of hulless oats for poultry is their high content of the soluble fiber beta glucan, which can impair the birds’ ability to metabolize the grain (Macleod et al. 2004). In non-organic poultry production, an enzyme can be added to break down the beta glucan molecule, but this is not permitted for organic producers.
WSU Mount Vernon trials conducted in 2014 explored the grain quality characteristics of hulless oats grown in western Washington. Oat varieties AC Gwen, Paul and Streaker were grown in replicated trials on farms in Skagit, Island and Thurston Counties to evaluate field performance and grain quality characteristics. (Field data is available from the PB website.)
A summary of grain quality data from the trials is presented in Table 1.
|Site (variety)||Yield, lb/a||Grain protein, % db||Methionine + cysteine, % db||Grain oil, % db||Grain beta glucan, % db|
Table 1. Grain quality summary from field trials of spring hulless oat varieties grown in three western Washington counties in 2014.
Data analysis by Anova showed that both trial location and variety had significant effects on grain protein, oil and beta glucan content (p<0.01). With respect to all three nutrients, the ranking of varieties were consistent across sites. These results suggest that variety choice may make a difference to feed performance of hulless oat grain.
Grain oil content of individual samples ranged between 7.6 and 10.6 percent dry basis (%db), representing higher concentrations than those reported as typical of wheat (2.4%db) and corn (4.0%db) (Welch 2011). All varieties were significantly different from each other in oil content, with AC Gwen producing the least grain oil (8.1%) and Streaker producing the most (8.6%).
Tested varieties performed well in terms of protein content, with a minimum of 12.8%db achieved across all individual plots. This was reassuring given the challenging conditions faced at some trial locations (e.g. strong weed pressure and low precipitation at Thurston County). These results compare well with typical grain protein content of wheat; under similar conditions, a soft white wheat might be expected to produce 8-10% grain protein and a hard red wheat, 13-15%.
Grain concentration of sulfuric amino acids cysteine + methionine in the trials were between 0.74% (AC Gwen) and 0.77% (Streaker). There was also a significant effect of entry on cysteine + methionine, Streaker and Paul having a higher grain content of these amino acids than AC Gwen. These results reflect the evaluation of total grain protein, which was highest for Streaker and Paul (18.32 and 17.91%, respectively), and lowest for AC Gwen (14.92%). The whole-trial mean value of 0.75% grain concentration of methionine + cysteine equates to 4.4g per 100g protein, which is in line with reported values for oat groats and exceeds values for whole grain wheat (3.7g/100g) and cornmeal (3.6g/100g) (Welch 2011).
Grain beta glucan ranged between 3.6 and 5.7%db. Both variety and location contributed to beta glucan content (p<0.01), though the effect of location was slightly stronger (MS=2.11 vs 0.65). Variety Paul had higher beta glucan content than varieties Streaker or AC Gwen. All results for grain beta glucan were high compared to those expected for wheat (0.83%db; Welch 2011).
Currently, hulless oats are rarely used in commercial poultry production. This includes in Western Washington, where commercial poultry rations are generally reliant on corn as a carbohydrate source and soy as a protein source. Before producers can consider the use of hulless oats, however, there should ideally be experimental work to establish that the inclusion of hulless oats does not result in a loss of egg productivity and quality.
The next stage of the locally-grown rations project is a poultry feeding trial. To learn more about the potential for replacing a proportion of poultry diets with hulless oat, a controlled feeding experiment will be carried out in conditions similar to those of a commercial laying operation. The main aim of this experiment is to determine the impact on (i) layer productivity and (ii) egg nutritional value of substituting wheat and maize in organic layer diets with hulless oats. To determine whether the above-described variety differences in laboratory grain quality results translate into biologically important differences in poultry diets, there different varieties will be tested separately. Oats are being grown organically at the Northwest Washington Research & Extension Center in order to supply grain to the trial.
- Winter peas
Peas are a legume crop, with high protein concentration in the seed, typically around 23% (Blair 2008). Whereas soy cannot be grown in Western Washington due to insufficient heat units, peas perform well in the region’s cool oceanic climate. Peas may be able to replace part of the soy component of poultry rations, providing a locally-grown protein source. A review of pea nutritional value in poultry diets found that inclusion of peas in poultry diets yielded satisfactory results in various trials at levels between 100g and 430g per kilogram of feed, depending on pea variety characteristics and other feed components, and that inclusion of peas in layer diets could improve yolk color (Blair 2008). Peas are higher in lysine than cereal grains (Igbasan et al. 1997), and may therefore complement low-lysine hulless oats to form a balanced ration.
Trials are in progress to test the field and nutritional characteristics of winter peas grown in western Washington. Five entries were tested in Whatcom County in 2013-14, including four commercial varieties (Granger, Melrose, Specter and Windham) and one breeding line. Winter temperatures as low as -10.1C (13.8F) were observed, but all pea varieties showed over 38% survival. The same entries were re-planted at the WSU Mount Vernon Research Center in fall 2014 with one further commercial variety (Koyote) and two breeding lines. Since the winter peas may be of interest as organic poultry feed, the trial is not herbicide-treated, and weed suppression capabilities of varieties has been evaluated. Large differences between varieties can be observed on the basis of this year’s trial data (Table 2). The trial will be harvested in summer 2015 and grain samples submitted for nutritional analysis. Based on nutritional evaluations of western Washington-grown hulless oat grain, the potential to formulate a locally-grown balanced ration using pea and hulless oat as the main components will be explored.
|Date of assessment:||1/31/2015||4/17/2015||4/17/2015||6/5/2015||4/17/2015||6/5/2015||5/7/2015|
|Entry||Breeding line / variety||Midwinter crop cover, %||Early spring crop cover, %||Early spring weed cover, %||Early summer weed cover, %||Early spring plant height, in||Early summer plant height, in||Downy mildew, % leaves infected|
|Pro 072-6034||Breeding line||5||31||56||65||50||41||18|
|Pro 132-7116||Breeding line||3||29||57||85||47||36||38|
Table 2. Field data from winter peas being grown at Northwest Washington Research & Extension Center, 2014-2015.
This work is undertaken in collaboration with professor of animal science James Hermes, Oregon State University. It is funded by the Clif Bar Family Foundation’s Seed Matters initiative and Wilcox Family Farms.
Farkhoy, M., Modirsanei, M., Ghavidel, O., Sadegh, M. and Jafarnejad, S. 2012. Evaluation of Protein Concentration and Limiting Amino Acids Including Lysine and Met + Cys in Prestarter Diet on Performance of Broilers. Veterinary Medicine International, vol. 2012.
Jacob, J. 2013. Synthetic methionine and organic poultry diets. eXtension online publication, eOrganic 7902. Accessed 9 June 2015 at http://www.extension.org/pages/69042/synthetic-methionine-and-organic-poultry-diets#.VXdPic9VhHz.
Macloed, M., Nute, G. and Wade, T. 2004. Avian feed efficiency from naked oats. Project Report LS3623, Department for Environment, Food and Rural Affairs. London, UK.
Macleod, M. 2004. Performance and egg quality in laying hens fed on naked oats. Project Report CSG15, Department for Environment, Food and Rural Affairs. London, UK.
Maurice, D. V., Jones, J. E., Hall, M. A., Castaldo, D. J., Whisenhunt, J. E. and CmConnell, J. C. 1985. Chemical Composition and Nutritive Value of Naked Oats (Avena nuda L.) in Broiler Diets. Poultry Science 64 (3): 529-535
Welch, R.W. 2011. Nutrient composition and nutritional quality of oats and comparisons with other cereals. In Webster, F.H. and Wood, P. J. (eds). Oats: Chemistry and Technology, 2nd ed. American Association of Cereal Chemists International, Inc., St Paul, MN.