Common New Zealand Grasses & Broadleaf Plants


DUWELL is passionate about bringing you the information that will make a profound difference to your horse's health and behaviour. 

Here you can learn about the types of grasses that are suitable for horses, the issues related to the various grasses, signs of mineral deficiencies and imbalances. 
Essential information for all horse owners.
First let's start with Horse Friendly Grasses - 
Brown Top

Regarded by some as a weed grass, because of its low quality, but for horse owners it is a very useful addition to pasture. It is non-endophyte, high roughage, low sugar and horse-friendly. It persists well in low-fertility soil, dominating unimproved hill and upland pastures, or poorly managed lowland pastures. Its quality can be improved with fertilizer. Its fine, dull leaves densely cover the ground and tend to smother clover growth which is a good thing! Seed can be purchased from most pasture seed suppliers.
Kentucky Bluegrass - Poa pratensis

Is a perennial species of grass native to practically all of Europe, northern Asia and the mountains of Algeria and Morocco. . The Spanish brought the seeds of Kentucky bluegrass to the New World in mixtures with other grasses. This grass does very well in NZ. It is high roughage, low sugar, non-endophyte and horse-friendly. Its is a valuable pasture plant, and prefers well-drained, fertile soil. It is also used for making lawns in parks and gardens.  
Prairie Grass - One from the "Brome" family of grasses

Studies conducted in New Zealand by AgResearch in the mid 90’s concluded that this grass is the horse’s favourite. In many ways this is a good thing as it is non-endophyte but it is reasonably high in sugar and does lack persistence when sown in pasture. Grazing brome and Smooth brome have better persistence in pasture and so would be a better addition to a mix for resowing.

The grass pictured is non-endophyte Cocksfoot. This is a horse-friendly grass that comes in a number of different varieties which are usually classed as "clumping" or "non-clumping" The first picture shows somewhat how it grows in clumps. This growing habit tends to be the older varieties whereas the newer varieties grow more evenly throughout pasture. This is a generally persistent grass but can take a few years to become properly established. Seed is available from grass seed merchants and they can recommend the best variety for your pasture situation. 
Timothy grass – or meadow cat's-tail

Timothy is a perennial non-endophyte, horse-friendly grass that grows in late spring and early summer and has low drought tolerance. It generally grows well in the South Island but can be planted in cooler inland area of the North Island. It provides high quality pasture and hay and is also grown as a chaff crop. In the USA it is grown for use in hay cubes.
Yorkshire Fog - or Fog Grass
Yorkshire Fog is a common perennial non-endophyte, horse-friendly grass that thrives in wet, infertile, acid soils. It is a very dense, hairy grass that can become dominant and unpalatable if not kept under control.  Horses do not really like to eat it but it is ideal for planting as part of a mix for horses that tend to be overweight. When cut as hay it needs plenty of drying so it does not become musty. Seed can be purchased for resowing and is a good option where less nutritious pasture is needed.  
The following grasses are ok in your pasture but do not look to sew them - 
Sweet Vernal
This is quite a common grass in North Island pasture. Has a sweet smell which comes from the coumarin, a naturally occurring chemical found in many plants, but in excess has a bitter taste which most likely is to deter animals from grazing on it. It also is an appetite suppressant. It is very common in pasture and generally horses consume it without problems. There is a "But” though…if the plant becomes mouldy, certain fungi will convert the coumarin into dicoumarol, a substance that inhibits normal blood clotting. Dicoumarol substance was responsible for the bleeding disease known historically as "sweet clover disease" in cattle eating mouldy sweet clover silage.
Check if your hay has sweet vernal and do not feed if it has any sign of being mouldy.  
The broadleaf weed or plant is considered safe for horses but they do not really like it. It survives in over-grazed situations and sometimes is the only plant in hard grazed areas of pastures. It can be high in problem sugars so is unsuitable for metabolic or laminitic horses.  

Endophyte ryegrass and annual ryegrass 

There are a multitude of reasons not to have rye grass in your pasture!! Sometimes we just can’t do anything about it but we need to be aware of what to look out for and what can go wrong. 
The stems and seeds of rye grass contain a fungus known as an Endophyte. This fungus lives off the sugars and nutrients produced by the rye grass. This fungus does not affect the growth of the grass neither does it perform a service to the plant. Farmers find endophyte grasses to have the advantage of being protected from grass grubs as they do not find endophyte palatable.   
The endophyte does however effect livestock and horses.  Symptoms can range from low grade symptoms that seem unrelated such as spooking and shying, excessive sweating, itchiness, skin allergies, photosensitivity issues such as sunburn and mud fever, muscle trembling, stressy herd-bound behaviour to full-blown serious health problems such as grass staggers that will cause the horse to lose of ability to walk properly, not be able to get up after falling or laying down, fall into fences, colic and laminitis. 
Rye grass can become very minerally imbalanced. It has an ability to uptake considerable amounts of potassium and protein, far in excess of the horse’s requirements. Symptoms of this are tightness and tenseness of muscles, flinchyness and sensitivity to being brushed or touch, erratic "crazy” behaviour, spooking, sweating easily and so on.  
Horses affected by ryegrass can benefit from being fed DUWELL Broad Spectrum Toxin Binder but pasture contamination may be too great and removing the horse from the pasture wold be the safest solution. Horses with these symptoms need to be removed from this pasture immediately. Serious health problems are just around the corner. Good quality non-rye/clover hay is less costly than extensive vet visits for fence injuries or colic.  
Endophytes in hay can remain in hay for long periods - months - so look for non-rye grass hay or a mix that has very little rye or clover.
Although annual ryegrass does not contain endophyte, the potassium content, photosensitivity related problems, high protein and sugar all go together make it unsuitable to feed to our horses.   

Clover – white, red and Lucerne
Like ryegrass there are many reasons not to feed clover or lucerne to your horses. 
Common problems caused by clovers and lucerne - 
Skin photosensitivity conditions such as sunburn and mud fever which in fact is not caused by mud rather the photodynamic pigments in clover and lucerne that once in the bloodstream react with the sun on white skin causing painful scabs. This condition can be completely eliminated simply by removing clover and lucerne from the diet. 
Clover is also very high in protein, starch, potassium and hormones none of which help our horses. All of the symptoms above for rye grass you can include for clover along with these next nasties. 
Cyanide - White clover also contains low levels of cyanide and over time is toxic– another reason to avoid it as much as possible. 
Hormones - clover can make mares ridiculously marish and geldings act like stallions due to the high levels of oestrogen throwing the horses system totally out of whack. Not exactly what you want. Starch levels are dangerously high and unsuitable for cresty metabolic and laminitic horses, increasing their risk of a laminitic attack. 
Even those horses not suffering with EMS or laminitis can have serious health problems develop from grazing clover. Ulcers can be caused by high sugar grasses lacking in fibre.    
Cats Ear

Here’s an excerpt from Massey University website: 
Horses affected by stringhalt have a peculiar action during which one or both hind legs are abruptly snatched up and held abnormally high. In New Zealand, the condition often affects both hind legs and is associated with nerve damage.
The condition begins suddenly, usually in late summer or autumn, and may affect the horse so badly that it is unable to move.
Stringhalt has been associated with horses grazing pasture containing large amounts of flatweed, Hypochaeris radicata (pictured) but experimental studies have not shown conclusive evidence for a link between ingestion of this plant and stringhalt (anecdotal client feedback does). Horses seem to be particularly vulnerable to flatweed that has been stressed either by drought or insect damage.
Kikuyu Grass
Kikuyu grass is what is known as an Oxalate grass. There are a number grasses containing oxalates in varying levels. Kikuyu is considered a high oxalate level grass.
The importance of calcium in the diet of horses and ponies is crucial. When coupled with phosphorus, the two minerals compose up to 70% of the total mineral content in the body. Calcium is necessary for skeletal, cardiac, and smooth muscle function, nerve conduction, and a host of other metabolic reactions. Ensuring adequate calcium intake is imperative and horse owners should be aware of substances that can impede proper absorption of calcium. Oxalates (strong acid compounds found in some plants) are such villains.
Oxalates bind to calcium in the gastrointestinal tract of the horse, prohibiting its uptake into the bloodstream and its subsequent use throughout the body. As calcium levels in the blood drop, hormones initiate reabsorption of calcium from the skeleton. This reallocation of calcium allows the muscular and nervous systems to function unhampered but only at the considerable expense of the skeletal system.
People sometimes mistakenly feed low bioavailable forms of calcium such as Dolomite (an insoluble natural mineral combination of calcium and magnesium carbonate) is not effectively absorbed from the small intestine of horses and provides no worthwhile protection against the effects of horses grazing oxalate grasses. Organic or chelated (bioavailable) forms of calcium offer the best protection. 
Oxalates are most detrimental to weanlings, yearlings, and lactating mares because of the substantial calcium requirements of these horses. Furthermore, these horses usually need considerably more feed than their adult sedentary counterparts, so the quantity of oxalates ingested will likely be greater. Proper skeletal growth of young horses is impossible in the face of calcium deficiency. Similarly, lactating mares fed oxalate-rich forages will produce calcium-deficient milk for their foals, which may contribute to developmental orthopaedic problems.
The concentration of oxalates in plants often rests on the climatic conditions and soil chemistry.
Oxalates become more toxic as plants mature. In summer pastures, oxalate concentration may rise as calcium levels subside. Oxalate content increases when pastures are fertilised with nitrogen and phosphates, such as poultry manure or N-P-K fertilisers. However, kikuyu grass which is short and dormant is generally not dangerous, even if large quantities are grazed, as the oxalate content is low.
Under some conditions oxalate poisoning can occur acutely, such as with the rapid introduction to and ingestion of oxalate-ridden plants, or slowly, such as with the continual grazing of oxalate-accumulating roughages.
Depending on whether ingestion is acute or cumulative, clinical signs may appear immediately or two to eight months following the onset of grazing pasture grasses high in oxalates. Degree of poisoning also depends on other variables such as the nutritional status of the horse and the amount of calcium in the diet. Typical signs of oxalate poisoning are laboured breathing, staggering, recumbency, depression, gastroenteritis, and diarrhea. Severe colic may occur in cases of halogeton toxicity.
Postmortem examination usually reveals calcium oxalate crystals in the kidneys and numerous other tissues and organs. 
The safety of a diet known to contain oxalates depends on the calcium to oxalate ratio. A diet that has a ratio of 0.5:1 or greater is generally regarded as safe. Kikuyu, buffel, pangola, and green panic grasses, for example, have been reported to have calcium to oxalate ratios of 0.23:1, 0.22:1. 0.37:1, and 0.32:1, respectively, indicating all are potentially dangerous. 
Therefore, it is recommended that every attempt should be made to reduce oxalate-containing
plants in pastureland and supplementation with a balanced bio-available supplement of calcium, magnesium, phosphorus and vitamin D is essential. 
Further work to identify pasture grasses, and have a ration evaluation by a qualified equine veterinarian or nutritionist should be conducted if consumption of plants containing oxalates cannot be avoided.
Kikuyu is also very susceptible to spikes in potassium content  when short lush growth appears following rain after a period of drought. Horse owners should be extremely careful in these situations in regard to the health and behaviour of their horses.