Rye Grass Staggers & Associated Loss of Production Emeritus Professor Ronald A Leng AO B.Sc., Ph.D., D.Rur.Sc. FASAP
Rye grass staggers is one manifestation of the effects sheep ingesting perennial rye grass that harbors endophyte fungi. Endophyte fungi are simple filamentous fungi that have formed an association with grass that mutually benefits both the grass and the fungus. The fungus that associates with rye grass is called Neotyphodium Lolli. This fungus is present in virtually all perennial rye grass pastures throughout Australia and New Zealand. It has a very simple life cycle as it grows between the plant cells and as the plant grows and sets seed it enters the seed head and as the seed germinates it then grows into the developing leaves and the life cycle is complete. It is heavily disguised as it never leaves the plant and can only be detected by sectioning the leaf blades and staining the fungus that can then be seen under the microscope.
The fungus and plant together produce some novel chemicals called alkaloids. These are similar to many of the drugs that people use to stoke out on. Endophytes react with the plant to improve water relationships and plants containing endophyte are more drought resistant. On the other hand plants infected with this endophyte produce three major alkaloids, lolitrem B, ergovaline and peramine.
Low productivity or ill-thrift, that can vary from difficult to detect levels to major reduction in productivity, are probably occurring year round on pastures dominated by rye grass as the alkaloids are produced in the growing plant continuously and are also in high concentrations in mature senesced pasture in the dry season and are unaffected when the pasture is made into silage.
Obvious ill-thrift that resembles intestinal parasite infestation, and some times catastrophic death rates can occur in sheep and cattle when temperature humidity is high and they consume the infected pasture.
Staggers are a mere reminder that the animals are consuming poisons and it is almost certain that insidious losses are occurring in the animals on that pasture. The other symptoms of endophyte toxicosis are also important resulting in economic loss and include a high faecal dags and wool stain around the rump. Diarrhea can be so prevalent in effected lambs to cause 20-30kg of dags that have to be removed and, of course, heavy contamination of the rear of the animal leads to fly strike that can hit the hip pocket more than having to crutch the lamb.
Lamb survival is compromised when ewes are on infected rye grass, as the ingestion of alkaloids reduces milk production and, at extremes, ewes will dry off soon after lambing with subsequent death from starvation of the lamb, particularly where the season is cold or wet.
In hot periods, there are recorded cases of large numbers of sheep drowning, apparently so over-heated from the ingestion of alkaloids that they bolt for water and animals are drowned in the subsequent rush. There are also cases where mishandling in the yards or running the animals back to the paddock has resulted in overheating and death of large numbers of animals.
Staggers whilst disturbing for the grazier, are indicative that there is a potential problem and the problem can be much more serious if the weather suddenly turns warm and where reproductive efficiency and survival rates of the lamb are reduced.
So is there anything that can be done? The problem arises where rye grass is dominant in the pasture, so the first step is to manage the pasture to ensure a good mix of other grasses and clovers so that sheep and cattle can select non-infected pasture plants.
If the pasture is dominated by rye grass then feed out other feed such as hay, silage (not made from rye grass as this will still have alkaloids in it) or probably a large bale of straw with high leaf content. In the latter case if the pasture is mostly dry then there should be mineral and urea supplements to ensure efficient digestion of the forage (use the Indicator System for best results)
If the problem of staggers persists then the animals may be better off on stubble with supplements until the dangerous periods are over. With experience, sheep can be moved if a moist hot front is predicted to pass through the district. If sheep are in late pregnancy then it is good idea to ensure the ewes are supplemented with other feed.
Where animals remain on rye grass pasture, then a good bet is to feed bentonite through a block lick such as the Olsson’s Bentobite block. The use of bentonite came out of research at the University of New England by Peter Fenn a Doctoral student who showed that feeding 15g of bentonite per day increased wool growth in grazing Merinos by approximately 25% or 1kg/year in small framed animals.
Bentobite has been trialed by graziers all over the country and is one of Olsson’s top rated blocks. In places providing bentonite, it has made impressive differences to the production of grazing sheep.
Claims by graziers that it lowers the incidence of diarrhoea in sheep and cattle are consistent with bentonite‘s known qualities in binding alkaloid toxins. Aflatoxins are amongst the worst carcinogens produced by a fungus that is present on grains and vegetable protein meals. It is readily absorbed and enters milk when contaminated feed is fed to dairy cows. Adding bentonite to the feed removed 60% of the aflatoxins from milk of dairy cows. This showed that bentonite can bind alkaloids and prevent them from being absorbed by animals. Bentonite has also been shown to bind the endophyte alkaloids but no trials have been done to see if feeding bentonite can protect grazing animals from the detrimental effects of these toxins.
The use of bentonite to lessen the effects of endophyte toxicosis is tentative, so any grazier who has a problem of staggers should be careful to test whether there are benefits from feeding bentonite.
A suggested routine would be to split a mob and feed one group Bentobite blocks. Prior to putting out the blocks walk among the mob and count the sheep that exhibit staggers and or have dags; put out the blocks and repeat the measurements in both the supplemented and non-supplemented groups. Cross over the treatments and repeat the measurements. Of course measurements should be made only after the sheep have come on to the blocks.
In conclusion, rye grass staggers are a symptom of potentially major production losses that occur when ruminants graze rye grass pastures. If it occurs on your property it is a fair bet that the lowered production is costing you an appreciable proportion of your profits. It is a major cause of production losses that requires some well-targeted research and it is suggested that the grazier should try bentonite as a supplement where cases of rye grass staggers arise.
Sorghum/Sudax Grazing Cattle and sheep grazing sorghum should be supplemented with salt and sulphur. This is the recommendation of the CSIRO after trials conducted at Armidale. Sorghum contains chemicals that are converted into prussic acid in the rumen. This is potentially lethal, but the ruminant can detoxify prussic acid by using sulphur. Sorghum is naturally deficient in sulphur and sodium (salt). Rumen microbes are inefficient when deprived of sulphur, digestibility is reduced and productivity falls. During the trials, salt blocks with 8.5% and 18% sulphur were used. With both blocks, feed efficiency and weight gains were increased dramatically. This research showed that sorghum could be safely and efficiently grazed while plant growth was optimum if a salt lick with sulphur was provided.
Stubble Feeding As summer approaches and feed in the paddock drops in nutritive value the annual dilemma of how to carry stock through the season is one that should be addressed. Given that the crude protein of pasture and stubble can drop to around 6% and stock require a feed ration of about 10% CP for maintenance it is obvious that stock will go backwards and production will suffer if the deficit is no addressed.
The problem then is to supply stock with sufficient protein, which is the major limiting factor, from an alternate source to fill the gap. Traditionally supplement feeding with grain has generally been the solution adopted by many graziers. This option leads to a situation, when the grain portion of the ration exceeds 30%, where the animal’s rumen pH level is lowered and becomes more acidic. The flow on of this is that the microbes that work on starch based feeds, such as grain, increase in number and those that help digest cellulose feeds, such as stubble and dry pasture decrease. This means that the animal is not able to efficiently digest the dry feed available.
The aim then is to have the animal’s rumen functioning efficiently to be able to digest the valuable and relatively inexpensive source of feed available in the form of stubble and dry feed. One method to achieve this is to supply the deficient nutrients to the microbes in the rumen in the form of a molasses and urea multi nutrient block. By supplying small amounts of supplement in this form the microbial population in the rumen is increased and more dry feed is able to be consumed and digested which in turn supplies more nutrients to the animal. It is the bacteria from the rumen that supplies the bulk of the protein for the animal as they die and are washed down the digestive tract to be digested in the true stomach of the animal.
Once the protein deficit is addressed then there is a need to consider the next limiting nutrient factor. Normally this is Phosphorous and Sulphur followed by other elements.
Once the rumen is functioning effectively, with the correct supplementation, stock will be in a far better position to hold condition and utilize feed generally considered to be of poor quality. Research that has been carried out by Professor Ron Leng and others at the University of New England; Armidale, established that stock can achieve higher body weight and wool growth when on a straw diet with the supplementation of urea and molasses in a multi nutrient block. Professor Leng’s work also established that by additionally supplementing a by-pass protein source, such as cotton seed meal, wool and body weight increase was even higher. This is because the by-pass protein source is digested in the true stomach and is not broken down in the rumen.
This theory has been put into practice in many countries where feed sources such as straw and stubble are readily available. The results have meant increased productivity and greatly assisted the viability of farmers. The flow on effects are also seen in increased fertility and survivability. Stubble is a valuable feed source when supplemented with multi nutrient blocks.
Here are many good reasons for not burning stubble and retaining it as feed for ruminants. Some of the most practical reasons are: Olsson’s have always promoted and encouraged “green” alternatives. The rationale of supplementing with multi-nutrient blocks is one that has been around for literally thousands of years. This rationale has its basis in the fact that ruminants were (and still are to some extent) nomadic animals, moving and grazing over large areas, thereby enabling them to attain a balanced selection of grasses, grains, minerals and vitamins according to their needs at particular times of the year. By supplementing ruminants with multi-nutrient blocks, you are in effect re-producing this nomadic nutritional environment by providing access to a balance of trace elements and minerals.
For Stubble feeding, Olsson’s recommend: Sulfos: for non-pregnant sheep, wethers and dry cows. Sulfos is an excellent mineral supplement to aid the digestion of dry pastures.
Dry Season with 10% Urea or 20% Urea: for non-pregnant cows, steers and dry cows. When the consumption of Dry Season 10% becomes high due to the increased needs for protein in animal, Dry Season 20% can then be substituted. This wills nearly half the consumption.
Peak 50: for pregnant animals in the last month of pregnancy and the first six weeks of lactation as well as weaners. If the blocks are with the mothers then the weaners will take to the blocks much more quickly.
Drought Feeding Tips There will come a time when dry feed is so sparse and the protein and energy levels so low, that no amount of supplementation will provide the animals with sufficient amounts of carbohydrates and hand feeding will become necessary.
Sheep Trials have shown that survival rates and average weights are better when grain is fed out once or twice a week. Bullies, after getting their rumen full will walk away and there will still be enough left for the timid sheep. Trailing causes less stress as more of the mob can get a feed without waiting. For a day or so after eating grain, animals will not feel like eating roughage, but will then be able to go back to it after their rumen recovers from acidosis (see Trouble Shooting Guide).
Cattle Leave grain in “dumps”, as cattle are unable to clean up scattered grain efficiently. Again, feeding once or twice a week leads to better survival rates. More animals maintain similar weights, rather than the bullies being fat while the timid animals waste away. Grain is digested more efficiently if processed but it may, in come cases, be uneconomical to process grains.
Pinched Grain Devalued pinched grain can be used effectively to feedlot cattle and sheep. The protein content of the grain is the determining factor for the addition of supplements to improve weight gains in animals and to improve the feed efficiency conversion ratio. Grains with crude protein levels below 13% should be fortified with a protein source and the calcium/phosphorus ratio balanced.