With harvest finished, those fresh stubble paddocks look like perfect clean fodder for sheep. As has always been the case, stubble paddocks can provide a good food source for livestock over summer. But can you push it too far, and when do you know you’ve reached the end of a paddock’s potential? Here’s how to get the most out of your stubble for sheep feed.
Are stubbles a decent food source – yay or nay?
In a nutshell, yes and no. Stubbles alone (as in the plant matter and stems) have poor digestibility and low nutritional value. However, the spilt grain, some plant matter, and weeds or volunteer plants can provide good quality feed over the drier months.
The problem is, as we get better at utilising harvest technologies and weed control, there is much less quality edible substances left in stubble paddocks than there was years ago.
Sheep need decent levels of food digestibility to maintain weight. Food substances with a digestibility of 55% or less will cause stock to start losing condition. It’s simple; the lower the digestibility, the lower the overall feed intake. It’s kind of like eating bowls and bowls of celery. The mass of fibre in the celery would eventually fill you up, but it wouldn’t include the calories you need to maintain or gain weight.
But that doesn’t mean we shouldn’t utilise stubbles. There is decent feed available, we just need to be smart about it.
So how much good feed vs indigestible feed is in a stubble paddock?
As you might have guessed, the answer clearly depends on the paddock and how it was managed. Everything from crop variety, to cultivation, harvest conditions, harvest methods, chaff management, moisture conditions, summer rains and weeds, etc. all come into play when factoring in a paddocks feed potential.
Roughly though, in fresh wheat stubbles approximately 1/4 of the paddock will have food substances with digestibility of 55% or more available, a 1/3 will be 50-55% digestible, and the remaining will be mostly indigestible. A survey of wheat stubbles found an average of ~100kg/ha was left available on the ground, and grain in barley chaff generally made up 2–3% of the material but was also measured as high as 8%.
To show it another way, the digestibility of grain (split on the ground) is around 80-87% digestible, any remaining plant leaves or trash will be around 40-50% digestible, and the actual stubble stem itself will be only 30% or less.
The take-home message is that the quality of a stubble paddock as a food source for livestock really depends on what is left on the ground other than just the plant stems.
So, how do I determine how much decent feed is in my stubble?
You can calculate roughly how much grain is available in the paddock by looking at 30cm x 30cm patch (an Akubra hat is a good substitute for a ruler) and count the number of grains on the ground. Using those numbers against the 100kg/ha guide below can give you an indicator.
The number of grains in a 0.1 m2 (32 cm x 32 cm quadrat) when there is 100 kg/ha of spilt grain:
Grain Type = # of grains
Wheat and Oats = 28
Barley = 25
Lupins = 8
Field Peas = 5
Faba beans = 2
How long can I keep sheep in stubbles?
Obviously, the answer depends on your stocking rates and the quality of your stubbles. As a guide, research from the GRDC Grain and Graze 2 program found livestock will lose weight when the stubble offers anything below 40kg of dry matter per hectare of spilt grain or 40 kg dry matter/ha of green weeds. To maintain their weight livestock need about 0.6kg of grain per dry sheep equivalent (DSE), per day. Using the table above to calculate grain kg/ha – you can roughly work out that if you had 100 kg/ha of grain in the paddock, you would get 100 DSE grazing days per hectare – assuming that last 40 kg/ha of grain is not utilised.
As a general consensus, after more than six weeks in stubble and reduction in dry matter of 45% of more, it is highly unlikely your sheep will be gaining weight. You can expect that most will be losing weight.
This is why additional supplementary feeding is essential for young animals or pregnant ewes, especially with foods high in protein such as lupins or peas. This is also why we recommend including loose lick or lick block supplements for other sheep.
Another way to check is by watching sheep activity. In fresh stubble paddocks, spilt grain is the main thing sheep are looking for and will naturally get eaten first. As a result, a Mallee study found that initially, sheep will spend about 30% of their time grazing looking for grain. Once grain levels fall, grazing time will decrease, and sheep will start to lose condition. So, once you notice them camping more and there’s a visible decrease in ground cover, it’s time to move them on.
In summary, timing depends on the quality of your stubbles. Grazing stubbles isn’t a set and forget program. Continually check both animal and paddock condition to make sure there is sufficient feed available, and ensure animals don’t decrease paddock ground cover past 50%.
Can it be as simple as not grazing past 50% ground cover?
On top of losing animal condition, you don’t want to graze paddocks after stubble or ground cover has declines past 50%. Not only will the animals be losing condition at this point, but you’ll also risk soil loss to wind erosion and moisture loss. If you’re a mixed cropping farmer, you’ll understand how vital soil moisture and soil health is to next seasons crop. So, it’s imperative not to overgraze. The 50% mark is a good rough guide for maintaining both animal and soil health.
So, what does this all mean in practice?
Cereal stubbles are a beneficial supplementary feed source, but they can be detrimental to both livestock and soil health if they are grazed for too long.
Stubble alone isn’t a good enough protein source for young growing lambs or pregnant ewes.
But even for dry ewes or wethers, you’ll still want to make the most of stubble feeds. Remember, after the spilt grain has been eaten, the remainder of the plant matter offers low digestibility and protein, and will eventually cause loss of condition. To make the most of the remaining plant matter and to uphold animal health and weight, we recommend using lick blocks or loose licks that are made for dry feed situations. Products you’ll see in our stores are blocks like Rods Dry Feed Urea.
Why you should use supplement licks or blocks.
Dry feed supplements help better utilise the poorer quality feed. Blocks and licks such as these use urea and other proteins to stimulate microflora in the rumen, which increases appetite and feed conversion.
Going back to our celery bowl comparison, say for instance eating one bowl made you full and couldn’t eat more. However, we could increase your appetite by adding a supplement, so you’d eat more, plus increase the utilisation of the nutrients in the celery. This is how these supplements increase total calorie consumption and add extra nutrients needed for maintaining health.
Our recommended top blocks for this summer:
Rods Dry Feed > great for all stubbles.
Rods Dry Feed 50 (higher protein) > great for stubbles and where more protein is needed.
Rods Dry Feed High Cal > great for summer grazing and if supplementing with grain or lactating ewes.
- As a guide, don’t graze past 50% decline in stubble matter/ground cover.
- Manage rotations in order of priority. Legumes and high-protein paddocks are best for ewes. Give ewe lambs access to the highest quality stubbles, followed by pregnant ewes (or in preparation for joining), and then older or dry ewes can be grazed on lower quality stubble.
- Add in supplement blocks such as Rods Dry Feed Urea or loose licks to help utilise the feed available.
- Be wary of grain poisoning – lactic acidosis. Try to climatise animals to grain before putting them straight into grain paddocks. For example, you start by grazing barley or lupin stubbles (these grains contain more fibre and less starch) before moving on to wheat. Or supplement feed with small doses of cereals before introducing stock onto fresh stubbles. Blocks such as Calcium Molasses can also be helpful.
- Make sure there is always access to fresh water.
- Cereal stubble does not contain sufficient protein for growing lambs or pregnant ewes, even with blocks. Try to supplement with feed such as lupins or pellets.
- If using supplements with urea make sure to keep them away from rain and moisture. Urea toxicity can occur in animals, so be mindful of what practice you’re undertaking. If unsure, talk to us.
Information and tables also sourced from:
Grain & Graze, (2004-2007, 2016)
Mallee Sustainable Farming – Top tips for stubble grazing