The search for roughage during a drought challenges many producers. Over many years, scrub and some native trees have become a ‘go to’ for producers seeking an alternative and cheap source of feed.
Many people have used scrub very successfully as part of their drought programs. However there are equally many occasions where results have been disappointing or have actually increased problems within the livestock program.
Image: ABC New England
So, just how good is scrub? I know many people will swear to the value of species such as Kurrajongs, Wilga or Native Apple. Mulga is an important species in the inland parts of the country.
However as with any feeding program, it’s never really that simple!
As can be seen in the table above, there is a fair bit of variation in the nutritional ranges of commonly fed species. Most species have an energy range of 7.5 MJ / Kg to 10.5MJ /kg. However in general the average is around 8.5MJ. In general its fair to say that the best-case scenario for scrub is that it is the equivalent of average quality hay. At these levels you really only expect scrub to provide maintenance levels of energy, provided your animals can eat enough each day!
The limitation for many scrub feeds is the level of Crude Protein (CP%). Many of the feeds that have been tested only provide enough CP to meet the maintenance requirements for dry animals. In practice this really means that if you are feeding to animals that are growing, pregnant or lactating, you will have to use a suitable protein supplement to meet these animals daily needs.
Not all stock will take to scrub. And not all scrub is as palatable as you might expect. It is important to use some local knowledge when looking at including scrub in your rations.
If you do start to use scrub, there are a few things to remember. Its important to try to use scrub that has a fair bit of leaf. Increasing twigs and small branches reduces animals overall intake of energy and protein. It also leads to risks of rumen impaction.
When working with producers who have had scrub in their programs, I’ve seen some useful tips. To educate your stock to scrub, start with small amounts close to watering points and stock camps. If needed you can spray a water molasses mix (2 parts molasses to 1 part water) onto the scrub.
When the stock recognize the sound of the saw, you should move away from these area and use trees and stands furthest from water. That way you can preserve the trees closer to water sources for when its hotter or if animals are weaker and won’t browse as far.
Impaction can be a real issue, particularly if there is not enough leaf material in the diet. Twigs can be an issue. Feeding molasses in troughs can help reduce this risk. Its also worth providing a supplement of ground limestone in the molasses mix at 1.5%. This will help maintain animals intakes of calcium.
Signs such as depressed appetite, no cud chewing or discomfort, often characterize impaction. You might notice animals groaning or even kicking their bellies.
Providing a protein supplement can also reduce the risk of impaction. A supplement will help stimulate rumen function and ensure material is digested more effectively. Suitable choices could be molasses and cottonseed meal (fortified molasses mix) or white cottonseed.
If you are cutting scrub, remember if you don’t cut enough, animals will be forced to eat more twigs and small branches. This can also increase the risk of impaction.
The final important consideration when feeding scrub is access to sufficient water. Stock must be able to access enough water each day. Reduced water intake can rapidly increase the risk of impaction, so water sources need to be clean as well as reliable.
Finally a couple of tips. Try to use only one species at a time. Otherwise stock might waste feed by choosing one species over the other. In hot weather you might have to feed more frequently than a typical 2-3 day program. Daily cutting might help avoid leaf loss as scrub dries out in the heat and becomes inaccessible to stock.
It is important to consider the way you cut and lop scrub. For regrowth its essential that you try not to cut too heavily, particularly preserving the trunk and major braches. Some foliage should be left to help the tree recover, ideally above stock browsing height. You should also really only lop a tree once a season to allow it to recover, although depending on the length of the drought, this period may be much longer.
Your own safety is vital! Climbing trees and using chainsaws are dangerous undertakings. When you are hot, tired or stressed the risk of injury is much greater. So consider ways to be safe. Can you do it early when its cool and you are not tired? Can you access a cheery picker or other method that means you don’t need to climb trees.
Keep thinking is there a SAFER way!
Finally after a few months, stock will lose their appetite for scrub. So I reckon it is important that your plan takes this into account. If you don’t know what the next phases might be, then why don’t you get in touch with me and we can work a plan out together.
Unfortunately cost isn’t actually an indicator of the feed value!
Feed value is actually determined by levels of energy; crude protein; digestibility, fibre and the amount of moisture contained in the feed. All these components contribute to the usefulness a particular feed has in meeting animals nutritional needs as well as impacting on the amount the animal can physically consume each day.
It’s actually pretty difficult to tell any of these things from a visual inspection. And while looking at a hay, or silage you might be able to have a guess it the digestibility of the plant when it was cut and the general moisture content, its only ever going to be a guess.
Over the past few months, many people have been full feeding their animals as the drought restricts paddock feed. A lot of these rations have been well planned and meet the various needs of the stock. However there are still plenty of rations put together on the basis of guess work! And by guessing some classes of stock are being underfed.
Obtaining a feed test is the most reliable way to determine the value of a feed. Its also is essential if you want to develop a ration that actually meets the needs of your stock.
Feed tests kits can be obtained through private companies or state departments of agriculture. Pretty much any feed can be tested. The kits will provide instructions regarding the amount you nee to collect to send away.
There are various levels of testing that you can request. For most situations, a standard evaluation is enough to give you the information that will help you know how useful your feed really is.
The things I look for include the following key components:
DRY MATTER (DM): All feeds contain some amount of moisture. This moisture has no nutritional value. When you prepare a ration, you need to allow for the water in the feed, and in many cases you will actually have to increase the physical or ‘as fed’ amount per animal to account for the moisture. If you don’t, your rations may end up being lower than what your stock need each day. Over a period of time, this can lead to significant underfeeding!
DRY MATTER DIGESTIBILITY: This explains as a percentage, how much of a feed your animals will be able to digest. Digestibility and energy are positively related, so having high levels of digestibility not only means your animals can use more of a feed, it also means that the energy levels of the feed are at a level that will meet their needs.
DRY ORGANIC MATTER DIGESTIBILITY: A further measure of digestibility is made on the organic matter of the feed. It is expressed as a percentage and again the higher the percentage, the higher value of the feed for animal production.
CRUDE PROTEIN: Crude Protein is expressed as a % of the Dry Matter. Crude Protein is essential for rumen function. Low levels will reduce the ability of a rumen population to effectively use a feed. For maintenance cattle require Crude Protein to be a minimum of 8%. Lower values may mean that you will need to add a protein source to your ration.
FIBRE: Fibre is an important part of a diet. Low levels of fibre can lead to digestive upsets. More commonly, in rations I’ve seen recently, fibre is often very high. High fibre not only lowers digestibility (and energy) but it will also reduce the amount of feed an animal will actually eat.
Fibre is measured by either; Acid Detergent Fibre (ADF) or Neutral Detergent Fibre (NDF). Acid Detergent Fibre (ADF) is a measurement of cellulose and lignin while
Neutral Detergent Fibre (NDF)is a measurement of hemicellulose, cellulose and lignin. Its possible to calculate how much of a feedstuff will be consumed by an animal by dividing 120 by the NDF.
Lower NDF figures will see your animals eat more, and so potentially achieve their needs more easily each day.
METABOLISABLE ENERGY (ME): The energy that an animal can actually use in its daily needs is refereed to as Metabolisable Energy (ME). It is expressed as Megajoules (MJ ME / kg of Dry matter). To maintain cattle the ME of a feed must be at least 8MJ. If a feed is below this level, you will need to add an energy source in order to achieve your stock requirements.
Knowing the levels of nutrient in your feed places you in a pretty powerful position! This knowledge will determine if the feed is suitable for the stock you are planning on feeding.
It will also help you determine the amount you need to feed. This information not only allows you to manage your animals more effectively.
It also means you will be using your feed more efficiently and getting the best return on the money you’ve spent to purchase it and feed it out!
Don't forget, you don't have to work these things out on your own. I'm always available to assist you with your feed tests, developing your rations or helping plan your strategies. If you want a hand, please don't hesitate to get in touch with me!
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