By Mary Crawford, Natural Resources Eyre Peninsula.
Stubbles are an important component of our mixed farming systems and are an essential source of feed for our livestock over the summer months; however some farmers rely too much on stubbles and overestimate the quality and quantity of feed on offer (FOO).
After harvesting your crop, a planned approach is required to ensure you get the best feed quality and quantity from your stubbles at that time and that this is efficiently converted to protein (meat and wool) through grazing. Stubbles differ in their quality and can deteriorate quite rapidly once the grain has been harvested; therefore to get the most out of the feed base, it is crucial that livestock are strategically grazed according to livestock class and growth stage.
In stubble systems it is also important to consider maintenance of groundcover, as sheep can very easily and quickly deteriorate the condition of the paddock, especially if they are walking around chasing feed.
The FOO in a stubble paddock consists of four components; standing straw, loose trash, residual grain and green material. The grazing value of the stubble is generally determined by the amount of residual grain (in the head or on the ground) and green material (volunteer weeds or shot grain) present, whereas the standing straw and trash have minimal value in terms of quality. The quantity of each of these components will vary between paddocks due to the type of crop, harvesting efficiency, weed control and canopy management.
A stubble feed base typically has large quantities of low quality feed (standing straw and trash) and smaller quantities of high quality feed (green material and grain). Cereal straw has low digestibility and poor nutritional value therefore sheep and lambs cannot eat enough to maintain weight.
As a basic guide, if the amount of grain or green material exceeds 40 kg/ha (Grain & Graze, Southern Farming Systems), livestock will gain weight.
The combination of feed quantity and quality will influence livestock intake and subsequently performance. Large quantities of low quality feed and limited amounts of quality stubble will reduce intake by livestock and they will lose weight.
To make an accurate assessment of the potential grazing value of a stubble, it is necessary to measure the FOO in the paddock, which will help to inform you if the grazing value outweighs the potential disadvantages (such as groundcover loss). This information will assist you to make an informed decision about when to start feeding supplements, and the stage at which the livestock should be removed from the paddock. It is important to consider the number and class of livestock you are grazing and whether you are targeting production or maintenance feeding, and how long the stubbles need to last to carry your livestock over the summer and autumn period.
For example, weaner lambs should be given the first pick of the best stubbles whilst they are growing, and later on in the summer months, ewes may have to become priority and graze the best feed if they are in their last trimester of pregnancy when they have higher energy and protein requirements. Pregnancy scanning will help you gain some insight as to how many lambs will need feed before winter pastures are available and ewe requirements at the critical time of lambing.
These things must be considered, and calculated, before grazing, to ensure that enough supplementary feed is on hand. Good quality hay and feed grain are generally the main options for Eyre Peninsula farmers, with some farmer’s also using perennial pastures, summer crops, chaff dumps, silage, perennial shrubs and pellets. Ensure any supplementary feed and watering points are located strategically around the paddock to prevent some of this behaviour occurring
Rotational grazing is critical to efficiently ration out dry feed / stubbles and to prevent overgrazing especially on sand hills and in paddocks where animals tend to graze into the wind; moving stock every week is most effective.
Stubbles can provide significant feed for livestock enterprises; however the challenge is estimating the amount of grazing value (FOO) in the stubble so an informed and measured decision, not an estimate, can be made about grazing the feed base.
Grain and Graze 3 project is currently developing a ‘Grazing Stubble Assessment Tool’ directly applicable to EP farmers (due for release 2016).