The cool winter temperatures of southern Australia are unfavourable for pasture growth and pastures cannot meet the demands for animal production. This results in what is referred to as a winter feed gap. In mixed farming systems there is a growing interest in the use of dual purpose cereals to fill the winter feed gap. Dual purpose cereals are grain crops that are grazed during the vegetative stage, then allowed to regrow and produce grain for harvest (Bell, Harrrison & Kirkegard, 2015). Some commonly grown dual purpose cereals are oats, wheat, barley, triticale and cereal rye. Advantages of dual purpose crops include a high quality winter feed source, the ability to spell pastures and grain production. Grazing management of these crops is key to ensure the risk of significant grain yield losses is minimised.
Varieties of dual purpose cereals
Varieties well suited to dual purpose use include:
Feed quality of oats, wheat, barley, and triticale is comparable when grown under similar conditions. The decision as to which cereal type and variety to grow, should be an agronomic one, with sowing date and rest periods key for crop recovery and grain fill. Long season or true winter types provide more flexibility than short season varieties.
Grazing management is key
Ideally plants should be well anchored in the ground before grazing, which generally occurs at the 3 leaf stage. However, a pinch and twist test to see if the plant pulls out of the ground is also a good test. From an animal management perspective there should be between 500-800kg of drymatter (DM)/ha for sheep and 1000 kg DM/ha for cattle to maintain good animal performance (Nicholson et. al, 2016). The grazing withholding period of any chemical applied to the crop needs to be considered. Failure to do so may mean the crop cannot be grazed at the ideal time.
Care needs to be taken not to graze the crop too hard, which is influenced by stocking density and length of grazing period. It is recommended not to graze plants below where the tiller stems change from white to green, as this can result in serve reductions in grain production. However it is now being suggested that in low rainfall areas only the top few centimetres of the plant should be grazed to minimise grain yield losses.
It is important that the grazing of a crop stops before the crop goes from vegetative to reproductive, marked by stem elongation (Z31 ). The plants require sufficient time to recover from grazing to allow good grain fill. If crops are grazed after stem elongation occurs, then grain loss can be massive, up to 3000kg/ha (Nicholson et. al, 2016). The best way to assess the growth stages of a crop is visually. It is also important to ensure the crop is grazed at the right stocking density to allow for even grazing. If the crop is not grazed evenly then it will not mature evenly, causing problems at harvest.
Dual purpose cereals are a source of high quality feed in winter that can fill the feed gap. If managed well, the same land area can produce both meat/wool and grain in the same season. However, poor management can result in grain yield losses.
Grazing Cropped Land: A summary of the latest information on grazing winter crops from the Grain & Graze Program http://www.grainandgraze3.com.au/resources/Grazing_Cropped_Land_June_2016_.pdf
GRDC: Dual-Purpose Crops Fact Sheet https://grdc.com.au/uploads/documents/GRDC_Dual-PurposeCrops.pdf
Bell, L.W., Harrison, M.T., & Kirkegaard, J.A. (2015) Dual-purpose cropping – capitalising on potential grain crop grazing to enhance mixed-farming profitability. Crop and Pasture Science 66, i-iv. Retrieved from http://dx.doi.org/10.1071/CPv66n4_FO
Bell, L., & Dove, H. (2012). Mineral supplements needed when grazing cereals. GRDC Ground Cover, 98. Retrieved from https://grdc.com.au/Media-Centre/Ground-Cover/Ground-Cover-Issue-98-May-June-2012/Mineral-supplements-needed-when-grazing-cereals
Nicholson, C., Frischke, A., & Barrett-Lennard, P. (2016). Grazing Cropped Land: A summary of the latest information on grazing winter crops from the Grain & Graze Program. GDRC. Retrieved from http://www.grainandgraze3.com.au/resources/Grazing_Cropped_Land_June_2016_.pdf
(AgVivo). Meat and Livestock Australia (MLA) (2013). More Beef from Pastures: Pasture growth. Retrieved from http://mbfp.mla.com.au/Pasture-growth
Advantages of dual purpose cereals
High quality winter feed
Feed quality and quantity influences the energy intake of stock which determines the level of meat/wool production (MLA, 2013). Therefore it is important that animals receive sufficient feed throughout the year and feed gaps are minimised. Dual purpose crops can potentially produce significantly more drymatter than pastures during winter, if well managed. The quality of these crops is equal to or better than winter pastures (Nicholson, Frischke & Barrett-Lennard, 2016). This can potentially result in high animal growth rates and/or reduced need for supplementary feeding during winter.
Wheat and triticale have a high potassium to sodium ratio which can induce magnesium deficiency (grass tetany) in livestock. Supplementation with magnesium and/or sodium can increase liveweight gains in sheep and cattle grazing wheat or triticale by 20% to 60% (Bell & Dove, 2012).
When a plant is grazed its nutrient stores are massively reduced. Therefore after grazing it is important that pastures have sufficient time to recover before the next grazing. If the time between grazing is too short, plants do not recover and are at risk of being lost out of the system. Slower growth rates of pastures during winter increases the time between grazings. The use of dual purpose crops means animals still have a winter feed source while pastures are spelled, allowing for plant recovery and persistence.
Good grain yields
Dual purpose cereals not only fill winter feed gaps, but can also have good grain yield if managed well. This means the same paddock can be used to produce meat and grain. Across 53 trials comparing grazed and ungrazed wheat, barley, triticale and oats the most common yield loss due to grazing was less than 250 kg/ha (25% of cases) (Nicholson et. al, 2016). In some cases grazing crops increased grain yield, possibly due to reduced lodging and less leaf disease as a result of early grazing. However at times losses of over 1000 kg/ha were observed, mainly due to poor grazing management (Nicholson et. al, 2016). Some of the dual purpose wheat varieties such as Kittyhawk, Wedgetail and Sunlamb can produce milling quality grain if managed well.