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Five Tips for Grazing Sheep on Stubbles
Did you know crop stubbles grown in Australia could provide about three billion ewe grazing days, or enough forage to feed Australia’s 65 million sheep flock for six weeks?
Most broadacre crops are grown in mixed farming areas, where cropping and livestock enterprises are combined. In these areas, stubbles make up an important part of the seasonal feedbase.
Why should producers graze stubbles?
- Stubbles provide a substantial feedbase component, with ewes in mixed farms typically spending 20% of their time on stubbles each year.
- Stubbles provide a high quality source of feed during summer.
- Removing spilt grain from paddocks reduces risk of pests such as mice or birds.
- Breaking down the stubbles makes the following cropping season easier as seeding into high volume stubbles can be difficult.
MLA and Australian Wool Innovation have co-funded the Modern Stubbles project to help producers understand how to effectively graze sheep on stubbles. Here, project lead researcher, Dr Dean Thomas from the CSIRO, gives his five tips for grazing sheep on stubbles.
- Maintain a good source of nutrition
Grazing stubbles is often done when ewes are pregnant so it's important they’re kept in good condition. Producers should aim for a condition score of three and have them on a rising plane of nutrition.
Stubbles are a feed source that starts as high quality but depletes quickly (as the sheep clean up the spilt grain) so producers need to keep this characteristic in mind to ensure a good source of nutrition is maintained.
Grains and young green plants have a higher proportion of digestible carbohydrates and protein, so they typically have a higher nutritive value. Leaf and fine stem components are low quality but generally edible, and make up roughly half of the energy for a typical diet from dry stubbles (where the remainder is grain and green material).
However, ripe wheat stems (that make up a large component of stubbles) have a high proportion of structural carbohydrates that are poorly digestible, making them lower in nutritive value and generally little of this material is eaten. - Prioritise stubbles for grazing
It’s important for producers to prioritise stubbles for grazing by: - providing ewes or finishing lambs with the highest quality stubbles, followed by pregnant ewes (or in preparation for joining)
- allowing older ewes to graze on lower quality stubbles, such as wheat or canola stubbles, although provision of adequate nutrition is still key.
- Keep an eye out for metabolic diseases
There are a few risks associated with grazing stubbles, such as acidosis. Spread out any piles of grain left in the paddock after harvest to reduce this risk. Acclimatise ewes first by starting them on barley or lupin stubbles prior to grazing wheat stubbles.
Vitamin E deficiency can occur if sheep graze stubbles for an extended period without access to green feed. Supplement with vitamin E (drenched or injected) or provide access to adjacent areas of perennial grasses and shrubs for a source of vitamin E. - Have the right infrastructure in place
Stubbles are a drier feed so producers need to have good fences and a source of water. Sheep will require 3–5L per sheep/per day to graze stubbles (more during hot weather). - Select paddocks carefully
Graze carefully on paddocks that are susceptible to wind erosion because grazing stubbles can break down ground cover, and sheep will often camp in susceptible areas such as hill crests and sandy patches. Extended grazing may result in sheep tracks that increase erosion risks.
Grazing Stubbles Made Easy
The Modern Stubbles project will develop a stubble grazing calculator. This excel-based tool will allow stubble grazing scenarios to be entered so producers can predict the likely live weight gain based on:
- the type of livestock
- type of stubble
- supplementary feeding.
Further testing of the stubble grazing calculator is now being planned to ensure it is ready for wide scale use by industry.
Trace minerals are vital to the reproductive performance of Beef herds. So even though they are a small inclusion into the diet of cattle herds, minerals pack a big punch, with deficiencies causing a reduction in production of up to 20-30%.
With the perfect storm of events this winter, the pimelea growth has skyrocketed. Like the conditions seen in 2021 and 2022, late winter rainfall, followed by cold weather and limited tropical pasture growth has resulted in increased pimelea growth. Pimelea is a native plant to Australia and New Zealand, with 150 identified species, of 110 are endemic to Australia. Of the species found around Australia, a small number (4) are associated with poisoning in cattle. P. elongata P. simplex subsp. continua P. simplex subsp. simplex P. trichostachya
Widespread summer rainfall has created a great pasture base for many producers going into winter. While this pasture base allows our producers to reduce the need to purchase hay or substitute feed, the quality of the pasture in winter will decline and will become a limiting factor to production. Understanding that diet quality effects passage rate in the rumen and therefore pasture intake is key to creating an effective supplement program, particularly during winter. Pasture quantity and quality are key drivers of production. As the winter months creep forward, nutrient density in pastures change, primarily associated with plant maturity. As grasses reach maturity, phase 4 or when seed head has lost all seeds, these plants are both low in protein and energy. During this time, it is important to assess grasses and provide stock with adequate protein and energy to prevent weight loss and maintain production. As plants mature and become more lignified, they become harder to digest. Due to this reduction in digestibility of plants, the movement in the rumen in slower and ‘gut fill’ increases. As a result, the animal is unable to consume the required pasture intake to meet daily requirements. Typically, tropical grasses, during winter have a Crude protein and metabolisable energy level of 6% and 5 MJ respectively. At this level, cattle cannot consume enough pasture to meet requirements, with particular emphasis on breeding stock with higher maintenance requirements due to pregnancy or lactation. Using supplements with high protein and mineral can allow cattle to digest dry pastures and provide supplementary protein for production.
Summer forage crops are a great source of feed and increases animal performance with excellent returns. As with other forage crops, the young green leaf and shoots of sorghum are the most digestible and initially have the highest feed value however sorghum has a toxic component in the plant when young, immature, and fast growing. Prussic acid poisoning has been recognised for many years in cattle grazing forage sorghum crops. There are many factors that influence the incidence of Prussic Acid poisoning, and the great news is, it’s preventable through management and nutritional supplements.
Winter supplements in Northern Australia are focused towards supplying increased protein where grasses are lacking. This is by far one of the most important parts of supplements in winter and a key component of maintaining breeder weights or improving growing animal weight gains. One of the biggest myths is; “Cattle cannot absorb phosphorus during the dry season”, this simply is not true. The factor of the most limiting nutrient is the biggest determination of how well a nutrient is absorbed. Dry season supplements address protein and energy deficiencies, due to these nutrients being the most limiting in dry mature pastures. Once these issues have been addressed, other nutrients become limiting, and the need of these nutrients presents itself. Phosphorus in the dry season is the third most limiting nutrient so the need for phosphorus becomes apparent when protein and energy deficiencies are met through supplementation providing urea.
Mulga provides a valuable feed source for stock, particularly through dry periods or drought. Mulga land types extend over areas of New South Wales and Queensland rangelands covering an impressive 20% of Australia’s landmass. Mulga provides supplementary feed to low quality pasture due to the mulga leaf retaining its nutritive value where grasses energy and protein level decline as they mature and die off. It is always important to consider the nutritional requirements for your stock and how to best meet these requirements. Important considerations when feeding mulga are the common deficiencies found in the plant and how supplements can counteract these problems and improve production. Stock can do very well on mulga; however, mulga has a low digestibility and much of the protein is bound by tannins.
Understanding that diet quality effects passage rate in the rumen and therefore pasture intake is key to creating an effective supplement program, particularly during winter. With the current season being drier than usual and many parts of Queensland and Northern New South Wales recording lower than average summer rain falls, it is time to start thinking about supplementation during Autumn and Winter. Pasture quantity and quality are key drivers of production. As the winter months creep forward, nutrient density in pastures change, primarily associated with plant maturity. As grasses reach maturity, phase 4 or when seed head has lost all seeds, these plants are both low in protein and energy. During this time, it is important to assess grasses and provide stock with adequate protein and energy to prevent weight loss and maintain production. As plants mature and become more lignified, they become harder to digest. Due to this reduction in digestibility of plants, the movement in the rumen in slower and ‘gut fill’ increases. As a result, the animal is unable to consume the required pasture intake to meet daily requirements. Typically, tropical grasses, during winter have a Crude protein and metabolisable energy level of 6% and 5 MJ respectively. At this level, cattle can not consume enough pasture to meet requirements, with particular emphasis on breeding stock with higher maintenance requirements due to pregnancy or lactation.
Dry autumn forecast . The Bureau of Meteorology suggests that the coming months will be drier and hotter than usual across most of Australia from the recent long-term autumn 2023 forecast. Warmer than usual daytime temperatures and drier areas emerging in some parts of Southern Queensland and Northern New South Wales, weaning and early weaning supplement strategies may prove an advantage before winter descends. Early weaning is often defined by weaning calves at a younger age than ‘normal’ practice. In Queensland, the ‘normal’ range of weaning is between 7-8 months, the range does extend either way dependent on environment. In extreme cases, early weaning (without milk replacer) can be performed safely and effectively down to 4-6 weeks of age, although calves that have reached 3-4 months are considerably easier to feed and manage. The main reason behind early weaning is the proactive management of breeding herds for improved productivity or due to feed scarcity. Pregnancy and lactation are a period in a cow’s reproductive cycle that causes extreme metabolic strain and can have drastic consequences on body condition, pregnancy rates, long term calf performance and possible deaths. The feed requirement for a cow with calf at foot are 50-65% higher than a dry cow, considerable damage to pastures can occur as a result of high forage demand. All calves are born with an underdeveloped rumen, and this continues to stay premature until calves come of an age where they start to forage. During the first few months, the rumen gradually develops, and rate of development depends on the nutrition, condition, and supply of milk from the cow and available feed in the paddock. Typically, calves can be functioning as normal ruminants between 3-6 months of age. Early weaned calves may not have a completely functioning rumen and most of their digestive tract functions largely like a monogastric animal (e.g., pigs), depending mainly on the abomasum and fourth stomach acting as the main digestive chambers. If a calf is old enough to be weaned from milk, a grain-based diet which can be readily digested should be provided as the main source of nutrition, as should hay/roughage to ensure the rumen continues to develop normally.
It is well documented that much of northern Australia is phosphorus (P) deficient and that P is required for almost every vital bodily function in cattle. However, supplement sales figures and industry feedback indicates that the majority of northern properties in P deficient areas are not supplementing their cattle with P over the wet season. Current thinking is that producers must not believe that they will get a good enough return feeding a P supplement to justify the expense and hassle of feeding supplement over the wet season. Past studies have shown that P supplementation increases growth, however, there have been few studies that have found a significant improvement in reproductive performance from P supplementation in northern Australia and quantified the benefit. This may be a reason why adoption has been so low. A trial commenced in 2014 at the Victoria River Research Station, Kidman Springs, to quantify the benefits of P supplementation. This trial will provide producers in P deficient areas with definitive data on the effects of supplementing females with P so that they are able to make better informed supplementation decisions. Brahman heifers born in 2014 were randomly allocated to either a +P (where phosphorus was supplied in the supplement) or –P (where phosphorus was not included in the supplement) treatment and grazed in neighbouring paddocks that were tested as acutely P deficient. Treatments swap paddocks in May each year to minimise paddock effects. Treatments are managed exactly the same year round, with the exception that their loose lick supplements either contain P (+P) or do not (-P). Composition of lick fed to each treatment can be seen in Table 1. Note: Soil test Colwell P levels: Acutely deficient: ≤4mg P/kg | Deficient: 5mg P/kg | Marginal: 6-8mg P/kg
Future Beef- Case study on the effectiveness of the right supplement on mulga country.
Nutramix is an Australian stockfeed and agri-processing businesses in Queensland and New South Wales. Operating since 2001, our head office and premix plant is based at Warwick, Qld
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