Grazing Cereals

• Overview
• Background
• Ways to graze cereals
• When to graze cereals
• How to graze cereals
• Estimating feed on offer from crop height
• Estimating feed on offer by cutting
• Grazing budget
• What species and variety to graze
• Fertiliser regime for grazing cereals
• Feed quality of grazing cereals
• Weed and insect control
• Other considerations

Overview

• The major reason to opportunistically graze cereal crops is to allow farmers to defer grazing on volunteer pasture paddocks, leading to an increase in the overall yearly pasture production. This results in more feed being available at the end of the growing season, helping to meet feed demand both at the beginning of winter as well as in the summer/autumn period.
  
• Grazing cereals allows farmers to change stocking rate without having to buy in or sell animals. This is done by changing pasture area and results in farmers better able to match the season with the stocking rate.
  
• Grazing of cereals early in the season allows producers to make the decision to continue grazing in dry seasons or to remove stock early and take the crop through to harvest in seasons when pastures are in abundance. By doing this, stock numbers can remain constant while grazing area is altered. Money is made in the better years by increasing crop area harvested
  
• Cereals have good early vigour, especially barley, and often reach grazing levels before annual pastures.
  
• All cereals, regardless of species, are a good quality feed source. Good live weight gains are achievable when grazing cereals as they have good metabolisable energy levels and are high in digestibility and crude protein.
• Grain & Graze research has shown that grazing cereals in their vegetative state has little impact on grain yield.
  
• The removal of foliage from grazing can reduce disease and insect burdens in crops. Insects generally thrive in warm areas with canopy cover. By grazing cereals, the reduction in canopy cover can reduce insect numbers. Cereal leaf disease, such as powdery mildew and leaf rust may be lowered through reduction of the susceptible leaf area.

Background:
Grain growers for many years have played with the concept of grazing crops with sheep and then letting them mature through to harvest. Although grain growers have felt that this could be done without causing significant damage to final grain yield, there was little trial work supporting the practice. Recent research by the Grain & Graze project has shown their suspicions to be right if done correctly. By grazing cereal crops farmers with mixed farming enterprises can significantly reduce autumn feed gaps and therefore lift carrying capacity and reduce other costs such as hand feeding.

Wheat, barley, oats and triticale show good growth rates after the break and can often become available for grazing earlier than volunteer and improved pasture systems.

Why Graze Cereals?

• The major reason to opportunistically graze cereal crops is to allow farmers to defer grazing on volunteer pasture paddocks, leading to an increase in the overall yearly pasture production. This results in more feed being available at the end of the growing season, helping to meet feed demand both at the beginning of winter as well as in the summer/autumn period.
  
• Grazing cereals allows farmers to change stocking rate without having to buy in or sell animals. This is done by changing pasture area and results in farmers better able to match the season with the stocking rate.
  
• Grazing of cereals early in the season allows producers to make the decision to continue grazing in dry seasons or to remove stock early and take the crop through to harvest in seasons when pastures are in abundance. By doing this, stock numbers can remain constant while grazing area is altered. Money is made in the better years by increasing crop area harvested
  
• Cereals have good early vigour, especially barley, and often reach grazing levels before annual pastures.
  
• All cereals, regardless of species, are a good quality feed source. Good live weight gains are achievable when grazing cereals as they have good metabolisable energy levels and are high in digestibility and crude protein.
  
• Grain & Graze research has shown that grazing cereals in their vegetative state has little impact on grain yield.
• The removal of foliage from grazing can reduce disease and insect burdens in crops. Insects generally thrive in warm areas with canopy cover. By grazing cereals, the reduction in canopy cover can reduce insect numbers. Cereal leaf disease, such as powdery mildew and leaf rust may be lowered through reduction of the susceptible leaf area.

Ways to Graze Cereals
Cereals can be utilised for grazing in numerous ways. Currently they are most commonly used for stubbles or cutting for hay and silage. Other ways that they can be used include:

• Standing fodder after maturity where both grain and remaining stem and leaf matter is consumed. Commonly oats is used in this way as there are less grain toxicity issue than with wheat or barley
  
• Grazing re-growth after hay and silage cutting
  
• Grazing throughout the season with no intention of harvesting. This can be an expensive form of feed but can be justified on a whole farm basis as it allows growers to better match the season to stocking rate
  
• Grazing early in the season then removing stock and harvesting (dual purpose)

When to Graze:

• Grazing can take place as soon as the root system of the cereal crop is strong enough that the plant won’t be pulled from the ground. This can be tested by the simple “pinch and twist” test. Hold the cereal plant between the thumb and forefinger and pull and twist at the same time. If the plant stays in the ground then it is safe to be grazed. This occurs somewhere around 4-6 weeks after emergence when the crop is beginning to tiller (Z14). This will vary depending on soil type and rainfall zone. Sandy soils will have to be left longer before commencement of grazing as plants will be pulled out of the ground easier compared to loams.
  
• Grazing after the crop has advanced past the stem elongation phase (Z30) can result is yield reductions. This is due to the animal removing the developing head of the wheat plant and/or the flag leaf which is responsible for the approximately 25% of grain fill of that head. In the NAR Z30 may occur 7-10 weeks after emergence depending on the sowing date, variety and rainfall. To best assess when the crop has reachedZ30. Exclosures should be placed in the crop to monitor the crop stage. When the crop in the exclosure reaches Z30 then the paddock should be de-stocked. If you anticipate grazing past this point then the grazing heigh should be increased or you should expect yield penalties.
  
• In the NAR the grazing window may be relatively short (2-4 weeks) due to the speed of development of crops especially if sown in May. To maximize the length of the grazing window growers should use long season varieties especially if sowing early May. In southern areas growers have more time (4-7 weeks) to graze crops.

How to Graze Cereals:

• Ideally the crop should be rotationally grazed with high stocking number to achieve an even grazing over the entire paddock this will results in a more even maturity and harvest time.
  
• Stocking rates of 20-40 DSE are commonly used
  
• Grazing to the “White Line”. This refers to the location on the plant where the stems of the tillers change colour from white to green. Allowing stock to eat down into the white part of the stem was considered detrimental to plant recovery. This may not be the case in higher rainfall zones.
  
• Large numbers of stock can be combined and used to graze large paddocks. This reduces the need for electric fencing and reduces labour costs during what is a busy period for growers. Growers in the NAR of Western Australia are grazing cereal crops with mobs of 1000 ewes or more.
  
• Work by Grain & Graze suggests that in the NAR 1 graze early in the season had no effect on yield.

Estimating feed on offer from crop height:
Measure the average height of the crop then refer to the following relationships

Table: The relationship between crop height and available DM (kg/ha) for crops shorter than 25cm.

These relationships are based on a 20cm (8“) row spacing sown at 100 kg/ha. Subtract or add 10% to the estimate for every 2.5cm (1”) increase or decrease in row spacing.

Estimating Feed on Offer by cutting
This method relies on access to scales with measurement in grams.

• Measure the length of 2m along a crop row.
  
• Cut the selected row to 25mm above ground level and collect the plant sample. Repeat another 4 times at random locations across the paddock. Combine all cut samples and weigh.

Compare the weight of the sample collected with the table.

Table: Relationship between collected sample. Row spacing and available dry matter (kg/ha)

These relationships are based on dry matter of 13.5%

Grazing Budget:
Matching stocking rate to the feed available is critical to achieve even grazing of a crop. A grazing budget involves estimating the amount of DM present, the amount to leave behind, a crop growth rate and the amount animals will eat.

• The amount of DM present can be estimated using the “crop height” method or the “cutting method”
  
• The DM left after grazing can be as low as 300 kg/ha but crop recovery will be slower.
  
• The crop growth rate will vary between regions but in the range of 30-40 kg/ha/day in June and 40-70 kg/ha/day in July. Your local agronomist will have more accurate figures.
  
• Animal consumption can be estimated by allowing 1 kg DM/DSE/day

Example Feed Budget – How many stock are required?

• A wheat paddock is measured at 700 kg/ha DM at the start of June and we want to graze it down to 400 kg/ha DM over 21 day period. The crop is growing at 30kg/ha/day.
  
• The total feed available is 300 kg/ha + 21days@30kg/ha/day = 930 kg/ha DM
  
• We have pregnant merino ewes available, rated at 1.5 DSE/ha. They will eat 1.5 kg DM/day or 31.5kg of DM over 30 days.
  
• The stocking rate required is: 930 kg/ha DM available/ 31.5 kg eaten per animal = approx 30 ewes/ha

What species and variety to graze:

• The best variety to use is the one that has been proven to achieve the best grain yields for your particular soil type rainfall zone and time of sowing.
  
• Longer season varieties will result in a longer grazing window and therefore better use of the grazing value of the cereal.
  
• The wheat varieties show that they are slower to the first graze than the barley, oat and triticale varieties.
• If you anticipate harvesting the cereal then the species to grow will depend on both commodity price and yield. In the northern agricultural region where it is difficult to grow barley suitable for malting it is normally best to use wheat as the grazing crop.
  
• Weed control and disease issues can also influence the species and variety decision. For example if brome grass is present then wheat or barley may be the best option as metribuzin can be used on some varieties of wheat and barley (eg most barley varieties except Hamelin as well as Eagle Rock.

Table 1. Mingenew Irwin Group (MIG) grazing cereal trial results (2007) showing yield and dry matter cuts for various varieties species and varieties.

Cut 1 Growth Stage – GS32 (2nd node detectible on the main stem)
Cut 2 Growth Stage – GS32

Fertiliser regime for grazing cereals:

• Crops should be treated as per a normal grain crop.
  
• Nitrogen applications should be applied after the first or second grazing depending on the pre emergent nitrogen rates used.
  
• Potassium may need to be applied at higher rates to account for potassium removed from the system by grazing

Feed Quality of grazing cereals:

Table 2. Mingenew Irwin Group (MIG) grazing cereal trial results (2007). Standard analysis results from each variety. Analysis done on samples cut at 1st grazing (mid tillering).

* DDM – Digestible dry matter, ME – Metabolisable Energy (calculated from DDM), CP – Crude protein (N content x 6.25)

Weed and insect control:

• Witholding periods need to be considered when deciding on what chemicals you should use to control weeds and insects. Read the product label before applying herbicides.
  
• Some weeds are likely to be better controlled when grazing is used. Commonly broadleaf weeds fall into this category where the spray-graze method can be used on weeds such as radish and capeweed.
  
• Some weeds are likely to benefit from the removal of the crop canopy early in the growing season. This is because the smothering effect of the crop is reduced from grazing. Examples of weeds that are likely to benefit from grazing cereals are ryegrass, wild oats, brome and barley grass.

Other considerations:

• Removal of foliage of the crop by grazing may result in less transpiration of moisture leading to more stored water at the finish of the season during grain fill
  
• Grazing will delay flowering by between 3 and 8 days. The earlier that grazing is completed the shorter the delay to flowering. This may lead to less frost exposure in some areas compared to ungrazed crops.
  
• Grazing cereals may occur around lambing time for some growers. This makes it difficult to move animals on and off cropping paddocks. Delaying lambing may be a way around this issue.
  
• Grazing cereal crops often results in lower protein levels and lower screenings.
  
• Growers have commented on better stubble handling with seeding machines at seeding in the year following the grazing cereal. This is due to the removal of the under-story of the stubble during the grazing process.
  
• The transition from dry feed to lush green feed at the beginning of the growing season can cause scouring in ruminants as they adapt to the change in food. It can take up to 2 weeks for stock to adjust to this change. Stock should not be put onto cereals when hungry to prevent gorging. Feeding hay to stock for 1-2 days before placing them on the cereal paddock and during the 2 week transition period is recommended. Stock will also need to be supplemented with magnesium (Mg) and Sodium (Na). Most cereals do not meet the Mg and Na requirements of stock and a simple equal parts mix of salt: causmag: lime is cheap and effective.

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