Why Livestock Grazing Australian Stubble Crops Require Extra Protein
1. Introduction
Grazing stubbles is a long-standing and valuable practice across Australian mixed-farming regions. Once harvest is complete, sheep and cattle are commonly turned onto wheat, barley, oat, and canola stubbles to utilise residual grain, leaf material, pods, and volunteer pasture. While stubbles provide cost-effective feed, they are nutritionally incomplete, with protein being the most limiting nutrient.
To maintain performance, protect animal health, and maximise paddock utilisation, animals grazing Australian stubbles almost always require additional protein supplementation
2.0 Nutritional Characteristics of Australian Stubbles
2.1 Low Crude Protein Levels
Across Australian cereal-growing regions, stubble typically contains:
- 2–5% crude protein in the straw fraction
- 6–10% CP when leaf, chaff, or grain residue is still present
- Much lower than livestock requirements (10–14% CP for maintenance; higher for growth and reproduction)
Modern harvesters, shorter crop varieties, and drier finishes have reduced leaf material and grain spillage, meaning today’s stubbles contain far less legume material and nitrogen than in past decades.
2.2 Declining Feed Quality Over Time
Australian stubbles lose nutritional value quickly:
- Grain and green pick are selectively eaten in the first 3–5 days.
- By 2–3 weeks, the paddock can be largely straw, which is low in digestibility and protein.
- Hot, dry weather accelerates bleaching and lignification.
2.3 Vulnerability to Mineral & Vitamin Deficiencies
Australian soils are often marginal or deficient in:
- Copper (particularly in sandy or coastal soils)
- Selenium
- Calcium (cereal stubble is naturally low)
- Vitamin E, especially after long dry periods with no green feed
These deficiencies become more obvious when protein is also inadequate.
3.0 Why Extra Protein Is Essential in Australian Systems
3.1 Rumen Microbial Activity in Dry, Low-Quality Feed
Australian stubbles are dominated by:
- Dry, fibrous stems
- High NDF (neutral detergent fibre)
- Low nitrogen
Rumen microbes cannot ferment this material efficiently without a nitrogen (protein) source. Supplementing with degradable protein or non-protein nitrogen (NPN) such as urea:
- Improves microbial activity
- Increases dry-matter digestibility
- Boosts voluntary intake
- Allows livestock to access energy locked in low-quality straw
This is particularly important in Australian systems where livestock often graze stubbles for 4–10 weeks over summer.
3.2 Supporting Australian Livestock Classes
Different classes of livestock typical in Australia have specific protein needs:
- Merino and crossbred lambs: Require high CP for growth and frame development.
- Autumn-lambing ewes: Need protein to maintain body condition ahead of joining and early pregnancy.
- Cattle on broadacre stubbles (common in QLD/NSW): Require added protein to maintain appetite and prevent weight loss during hot, dry summers.
- Weaners: Are the most vulnerable stock class and deteriorate fastest on low-protein feed.
3.3 Health and Production Issues in Australian Conditions
Protein supplementation prevents key issues commonly seen on Australian stubble diets:
- Swayback (copper deficiency) in lambs
- Reduced fertility in ewes and cows due to poor body condition
- Weaner ill-thrift
- Loss of appetite, leading to rapid body condition decline
- Reduced wool growth in Merinos
Supplementation ensures animals maintain condition when pasture is unavailable.
4.0 Managing Risks in Australian Stubble Grazing
4.1 Acidosis From Grain Residue
Many Australian stubble paddocks contain:
- Header trails
- Patchy grain spillage
- “Hot spots” in wheel tracks
This uneven distribution increases the risk of grain gorging and acidosis, particularly in sheep or cattle not adapted to grain.
Protein blocks or loose mixes containing buffers help reduce this risk.
4.2 Mycotoxin Risk in Wet or Late Seasons
In high-rainfall zones or wet harvests:
- Stubbles can contain moulds, fusarium, or head blight residues
- Mycotoxins can cause scours, appetite loss, and ill-thrift
Supplementing with toxin binders may be necessary in these seasons.
4.3 Toxicity Risk With Supplements
- Urea/NPN must be fed safely and consistently.
- Copper-containing supplements must only be used when deficiency is confirmed.
Australian sheep, in particular, are highly susceptible to copper toxicity.
5.0 Economic Benefits for Australian Farmers
5.1 Extending Stubble Utilisation
Protein supplementation allows livestock to:
- Digest more straw
- Stay on stubbles for longer
- Reduce pressure on conserved fodder (hay, silage)
In dry years, this can save thousands in feeding costs.
The Dickson Ag Stubble Grazing Salt Block has been formulated specifically for these Australian conditions, supplying the protein and minerals livestock need to effectively utilise stubble while supporting intake, health, and condition. Incorporating this block into a stubble grazing program helps producers maximise the value of their crop residues and maintain livestock performance across the toughest dry-feed periods.