| ||What is chaff? | Background | Feed testing | Feeding chaff | Crop acre requirements | Economic assessment
Over the years, many cost-conscious cow/calf producers across western Canada have recognized the potential for chaff residues to help reduce the winter feeding costs in mixed farm operations.
Chaff that has often been considered a nuisance on the grain side of a mixed farm can prove to be a valuable low cost feed alternative on the cattle side. In fact, chaff may prove to work as a win-win solution for both operations, if some basic steps are followed. And nothing is more important than to first recognize that chaff is a low quality feed, suitable only for mature beef cows.
What is Chaff?
Chaff is made up of glumes, hulls, unthreshed heads, short straw, leaf material, weed seeds and whole or cracked kernels from the harvested crop. As a result, chaff has a higher nutritive value than straw.
Collection, handling and feeding
Chaff can be handled and collected in either of two ways. It can be collected and dropped on top of the straw swath, where it can then be baled using a cyclone type of attachment, or it can be collected and blown into a chaff wagon using a chaff collector. The wagon then dumps piles of chaff in the field for later collection or field feeding.
The first method of collection and handling is easy and requires a minimum of equipment purchases or modifications. Once baled, the chaff can be fed in round bale feeders, rolled out in the field, or tub ground and mixed with other feeds.
Chaff piles left in the field may be grazed or moved to a central feed pile and fed. Field grazing of chaff is relatively inexpensive, efficient and effective. Electric fencing may be used to limit access to chaff piles.
Field feeding is preferable to corral feeding because little if any yardage is taken up with the field-feeding scenario. Corral feeding may also prove more expensive simply because there is a transportation cost associated with removing the chaff from the field. One issue with field feeding is the potential for the development of small thick mats of straw around field feeding sites. These areas may suffer from poor germination and weed infestations in the following year.
If yard feeding is preferred, most chaff piles can be collected using a forage harvester or a hay sweep on a front end loader. (This feeding method also removes weed seeds from the field.) Once in the feed yard, the chaff can be mixed with other feeds, or it can be piled and fed free-choice. An electric wire may be used to limit access to the chaff pile.
The advantages of mixing chaff with silage are that producers are better able to stretch their feed resources and better match the feed to animal requirements. Transportation is the biggest issue concerning the economics of chaff. Chaff is very light but very bulky, which makes it costly to move long distances.
Why feed test?
As shown in Table 1, chaff quality can vary. The major factors that influence quality are crop type, stage of maturity, weed content, method of harvest, combine settings and crop and field variability. Chaff from oats and barley generally has a higher nutritive value than wheat, pea or canola chaff. As a result, it is important to use feed testing to determine feed value.
Feed sampling procedures
Use a core sampler to get samples from baled straw with chaff. For round bales, take about 20 samples from different bales. Sample from the round surfaces of the bales at a variety of locations. For rectangular bales, take 1 sample per bale from at least 20 bales. Take the samples from the middle of each bale end. Place the samples directly into a plastic sample bag.
Chaff piles can most easily be sampled by hand (Figure 1). Take at least 20 samples from a variety of different piles at different locations and depths to obtain a representative sample. Place these samples on a smooth surface and mix. Divide the sample to obtain a sub-sample sufficient to fill a standard forage sample bag (about 2 liters).
Figure 1. Chaff pile
Special care should be taken to ensure the sample is representative; heavier and lighter chaff components must be adequately represented. Ask that the feed testing laboratory grind the entire sample to ensure that the sample is representative of the original chaff.
What to test for
Feed laboratories offer many different analysis packages. The test or tests you choose will depend on your own needs and budget. Most packages of analyses include levels of crude protein, acid detergent fibre (ADF), neutral detergent fibre (NDF), calcium and phosphorus. The laboratory will use this information to estimate energy levels for you. You may also wish to test for trace minerals levels at least once every two or three years to assess the adequacy of your trace mineral supplement program.
Two methods of feed testing are available to beef producers. The wet chemistry test consists of simple chemical analysis. Near Infrared Spectrometry or NIRA method uses light wave analysis. Unfortunately, the NIRA test uses localized databases (different growing conditions than your own). In addition, most of the feeds tested are of high quality, so feed quality estimations of low quality feeds are often inaccurate. Although the wet chemistry analysis is more costly, it is considered to be the more accurate method of testing chaff.
Using feed test results
To meet livestock nutrient requirements, chaff/straw rations will generally require some supplementation for protein, energy, minerals and vitamins. Software such as Cowbytes provides a quick method to properly balance nutrients in chaff/straw feeding systems. Further information on Cowbytes can be located on Alberta Agriculture’s website Ropin’ the Web.
Quality variability in chaff
Several variables can affect chaff feed quality:
Table 1 provides a summary of the nutrient values for chaff and straw residues. Data represents more than 200 field samples taken during 1996 to 1998 in northeastern Alberta.
- Combine settings: The more grain in the chaff, the better its feeding quality. If there are a large number of small kernels in the sample, the combine can be set to throw the light kernels over to the chaff, thereby improving the quality of the chaff. If the sample contains more broken straw than bits of grain and leaf material, it will have a lower feed value.
- Combine efficiency: The poorer the efficiency, the more cracked grain and unthreshed heads that will pass over the sieves and into the chaff.
- Underseeding: Underseeded crops such as alfalfa add green leaf material to the chaff, increasing crude protein levels.
- Stubble height: Higher cutting heights such as with direct combining can produce straw with higher nutritive values than when cut at ground level. Although this approach will reduce total straw yield, it will help in improving the overall quality of the chaff sample.
Table 1. Average feed values for all chaff and chaff/straw combinations
Source: Alberta Agriculture, Northeast Conservation Connection and Agricultural Service Boards, 1996-1998 Northeast Alberta Chaff and Chaff/Straw survey
|Wheat chaff and straw|
|Barley chaff and straw|
|Oat chaff and straw|
|Pea chaff and straw|
* ADF – acid detergent fibre
** TDN – total digestible nutrients
General recommendations for chaff or chaff/straw feeding
As indicated in Table 1, the nutrient values for chaff or chaff/straw combinations are generally too low for growing livestock. As a result, chaff or chaff/straw roughages are best suited for mature animals in good body condition (Body Condition Score (BSC) 3.5 Canadian scale). Animals in poorer condition or still growing should be segregated and fed a separate ration that will meet their nutritional requirements.
To identify the appropriate supplement and mineral mix for your operation, contact your local ruminant nutritionist.
- Use protein supplements in chaff/straw combinations when chaff crude contains less than 6 per cent crude protein. Protein supplementation will enhance the digestion of low quality roughage.
- Adjust ration supplementation during winter feeding. For mature pregnant animals both protein and energy requirements increase during the second and third trimester.
- Protein sources such as lick tanks that contain high quantities of non-protein nitrogen are not as effective as natural protein sources when supplementing low quality forages.
- Plant-based supplements such as canola meal or alfalfa hay are a more effective form of protein supplementation. However, supplements such as canola meal require mixing with other feeds to achieve adequate feed intake.
- Concentrate supplements can be used to supply protein (15% crude protein or greater) and energy (75% TDN or greater). Mixing with other feeds may be required to achieve required feed intake.
- Supplemental minerals, salt and vitamins need to be provided when chaff/straw rations are fed.
Table 2. Example rations: Winter feeding 1,300 pound mature cow in mid-gestation, BSC* of 3.5
* Body condition score
|Barley chaff (In field)|
|20% protein pellet **|
** Pellets are plant protein source with mineral mix
Crop Acre Requirements
As shown in Table 3, chaff and straw yield will vary by crop type and soil zone. Harvesting systems will also affect the quantity of chaff or straw produced. As result, the number of crop acres required for a feeding program will vary with chaff yield, feed waste and animal intake.
For example, a chaff yield of 600 lbs/acre with 20 per cent waste and estimated daily intake of 30 lbs of chaff for a 30-day feeding period will require approximately 2.0 acres per cow.
|30 lbs chaff/day x 30 days |
|600lbs chaff x 80% (20% waste)|
Table 3: Typical amounts of harvestable straw and chaff per bushel of grain
* Amount of harvestable straw, assuming about 80 per cent recovery in cereals, and 50 per cent in peas and canola, with 2 to 4 inch stubble left
Pounds of straw
per bushel of grain*
Pounds of chaff
per bushel of grain**
20 - 25
20 - 25
5 - 10
5 - 10
15 - 20
20 - 25
** Amount of harvestable chaff, assuming no weed chaff
Source: Estimating the Value of Crop Residues, Agdex 519-25. March 1999.
Chaff can be a dependable and economical feed source for winter feeding programs. However, it is important to know the costs associated with feeding chaff such as the costs for chaff collection, supplementation and feeding management. As shown in Table 4, the operational costs to collect chaff on per ton basis are relatively low. Because chaff is a low density product, moving it to a central feeding area can result in a significant increase in feeding costs (Table 5).
Table 4. Examples of in-field chaff collection costs per ton
Assumptions: Chaff yield of 600 lbs/acre; inputs for fuel, labor and repairs based on 2% increase in combining time, depreciation and maintenance costs for chaff collector.
Table 5. Estimated delivery costs for 100 tons of chaff
|Equipment requirements||Cost per ton|
|Tractor with loader|
25 hrs x $40/hr = $1,000/100 tons
Hauling 5 miles at $90/hour at 4 tons/hour
25 hrs x $90 = $2,250/100 tons
|Chaff delivery cost||$32.00/ton|
Assumptions: 2006 custom rates for tractor and truck.
As shown in Table 6, chaff feeding provides an opportunity for livestock producers to reduce their winter feeding costs in comparison to drylot feeding. A market value for chaff is hard to define, so in this assessment, chaff has been valued at cost while other feeds are at market value. The economic advantage of chaff feeding depends on low production costs and in-field feeding systems that help reduce yardage costs. Cost’s associated with feed supplementation, water provision or electric fencing may affect the net economic advantage of chaff feeding.
Table 6. Example in-field chaff grazing expenses versus drylot
* D. Kaliel, Yardage – The Cost Beyond Feed.
|Grass/legume hay ($60/ton)|
|20 % protein pellet ($170/ton)|
|Feed delivery/yardage *|
|Feeding management (electric fence/labor)|
Assumptions: 1,300 lb cow mid pregnancy, 30 lbs/day chaff or hay, 5 lbs protein supplement provided daily for chaff, feed delivery includes labor and equipment.
Chaff or chaff/straw blends can serve as a source of feed for winter rations; however, it is important that the rations be well balanced to ensure the cow’s nutritional needs are being met. The economic advantages of in-field feeding would suggest that livestock producers should consider utilizing chaff in winter feeding programs. Consult your local ruminant nutritionist for assistance with ration formulation and costing chaff-based rations.
For more information, contact
Alberta Agriculture and Forestry
Ag-Info Centre toll-free: 310-FARM (3276)
Northeast Conservation Connection and Agricultural Service Boards
Alberta Agriculture and Food, Direct Seeding: Estimating the Value of Crop Residues, Agdex 519-25. 2007.
Block, H.C. Dubeski, P.L. McCartney, D.H. Ohama, A.J. 2006. “Review: The composition and availability of straw and chaff from small grain cereals for beef cattle in western Canada.” Can.J. Anim. Sci 86: 443-455.
Kaliel. D. Yardage – The Cost Beyond Feed. Alberta Agriculture and Food. 2005.
Source: Agdex 420/50-2. Revised January 2008.