by Antony Meyer Jones


The aim of this study is to compare & contrast various types of hay, both single species & mixed crops, with regards to their suitability for performance horses. British & European grasses & legumes have been the main areas of this study, although some predominantly North American species have been included. The comparison has been made via several factors such as: Quality, Palatability, Availability, Cost, Adverse effects, Compatibility with other foodstuffs and "Home" Production.


Although concentrating on "straight hay" a brief reference must be made to the questions of silage & treated hays. Silage has not been popular with horse owners, but good quality silage is a suitable feed. Problems occur with silage of poor quality; if the pH of a made silage crop is not below 5.5 the bacterium Botulinum Clostridium, which is endemic in soils, is able to produce an endotoxin that causes Botulism. Each year several horses die in the UK due to Botulism. This can often be traced back to "Big Bale Silage" that has not been treated with a preservative and whose pH is circa 6. Interest has arisen in treating hay with a mixture of volatile fatty acids, to act as a preservative. Illinois & Cornell Universities carried out a study treating hay with a mixture of 80% propionic acid, 20% acetic acid (details as in Table 1). Horses given a choice preferred the untreated hay, however when given no alternative, they ate their full ration in treated hay & with no adverse effects.

Table 1

% Harvesting Moisture Field Losses Feed Losses Total Loss
Treated 27 10 6 16
Untreated 17 17 13 30

Thus, not only was preservation of the hay improved but also since the hay could be harvested with a higher moisture content, this may be an extremely useful technique in poor summers as an alternative to barn drying. An alternative treatment yielding similar results is Cider Apple vinegar.

Major Species involved during hay conservation.

The following groups may be considered as the major contributors towards hay production : Ryegrasses, Fescues, Timothy, Cocksfoot, Meadow Grass, Legumes, Cereals. For a typical analysis of hay made from these, please see Table 2.

The basic characteristics of the main species chosen for horse pasture are as follows :

[a] Perennial Ryegrass (Lolium Perenne) is very persistent in good rich soils but tends to decline after 2 to 3 years on poor light soils unless it is kept well fertilised. Since it is a useful base for seed mixtures, it is found worldwide.

[b] Red Fescues (Festuca Rubra) have a large variation of quality but the best are palatable & have good nutritional quality. They have poor establishment ability but are hard wearing. For this reason they are popular for sports fields & the seed is appropriately expensive.

[c] Rough Stalked Meadow Grass [Poa Trivialis] has a close growing habit. It is best grown on moist soils & in sheltered conditions. Due to its close growing habit it fills the bottom of the pasture & thereby keeps out weed species.

[d] Smooth Stalked Meadow Grass probably best known as Kentucky Blue Grass, is useful on light & sandy soils since it is stoloniferous and resistant to severe drought.

[e] Timothy (Phleum Pratense) produces possibly the most palatable hay for horses. It's seed is relatively cheap due to the abundant seed production of each plant. Moist soils are preferred, such as : heavy loams, clays & peat soils.

[f] Wild White Clover (Trifolium Repens) Deep rooted & drought resistant. Low levels of clover inclusion are often required but high inclusion rates may provide an excess of protein. This wild white clover is to be generally preferred over the more vigorous cultivated varieties.

Table 2

Calcium Phosphorous Dry Matter C. Protein
Hay Types by % DM by % DM % by % DM
Cocksfoot/Clover 0.91 0.31 82 12.3
Cocksfoot/Lucerne 1.37 0.3 79 15.2
Italian Ryegrass 0.51 0.24 80 9.7
It. Ryegrass [Barn dried] NA NA 88 8.5
Mixed Ryegrass NA NA 80 6.8
Part-cured Ryegrass 0.57 0.3 55 12.9
Fescue 0.54 0.25 84 9.4
Timothy 0.48 0.21 86 7.4
Meadow Grasses 0.68 0.22 84 8.7
Artif.-dried Clover NA NA 89 15.4
Mixed Legume 1.44 0.27 85 14.5
Cereals & Legume 1.11 0.22 83 11.8
Oats 0.41 0.29 84 8.2

Cost & Availability

Both of these factors vary widely with season & weather during that year. There are only a few specialist growers who cater specifically for equine needs; most forage must therefore be purchased from farmers & dealers whose main concern is for other agricultural animals. It is often the case that the most available & cheapest hays have a high meadow grass content. More specific ryegrass / timothy hays tend to command a significantly higher price. In order to obtain lucerne, fenugreek or other specialist crops one may be able to buy the prepacked & chopped product from the local feed merchant. If not, the crop may be obtained by fostering a relationship with a specialist producer; for example. Lucerne hay may be purchased by the bale in the Newmarket district, straight from the producer.


Despite the importance of this characteristic [if a horse will not eat the hay, then the hay is of no use] very little research has been carried out to study this. In fact, to my knowledge, no grasses have yet been bred with this specific characteristic in mind. However, in 1980, Mrs M. Archer published a paper on her preliminary findings carried out at the Equine Research Centre, Newmarket, England. The work was carried out with grazing horses, the results being summarised as follows :

Table 3

Much favoured Less Favoured Not Favoured
Hybrid Ryegrass
Augusta, Sabrina
Perennial Ryegrass
S23, Melle, Condor, Sillian
Meadow Foxtail
Timothy, S48, S50
Tall Fescue
Alta, Dovey
Brown Top Cocksfoot
Prairial, Cambria
Creeping Red Fescue
S59, Reptans
Meadow Grasses
Kentucky Blue Grass
Meadow Fescue
Crested Dogstail nn nn

However, 3 points should be noted when considering the results :

[i] all grasses were grazed at a fixed height and thus at different growing stages, yet palatability is known to vary with growing stage.

[ii] Palatability and therefore the horses preference will probably vary between the growing crop & hay. Could this explain why Timothy is not favoured here but is considered favourably as hay.

[iii] A further variation may be caused by exogenous factors such as soil type or climatic variation.

Adverse Effects

Providing that the hay to be fed is free from toxic plants such as Ragwort (Senecio Jacobeae) then few adverse effects are normally noted when feeding good quality hay. However, a few points should be made :

[A] If contamination with fungal spores is suspected then hay may be soaked in water or a water/molasses mix, in order to reduce any respiratory risk. The reasoning is as follows; soaking will swell any spores to a greater diameter than that of the bronchioles within the horse's respiratory tract. The cilia {fine hairs} within this region can then remove the spores before they can causes blockages within the lungs. To swell the spores sufficiently, soaking should be carried out for at least 12 hours. It appears that leafy hays made from meadow grass are more susceptible to this problem than are the coarser ryegrass hays.

[B] Photosensitisation of predominantly chestnut horses has been noted as below : A susceptible horse {perhaps carrying a gene predisposing him to the condition} is fed upon hay containing high levels of trifoliates [esp. clover, alfalfa & fenugreek]. The horse is then wormed with a thiobenzadole wormer. Shortly afterwards the horse may break out in sores that secrete pus, particularly on the lower leg & face. Even treatment with cortisone creams will not cure the sores yet 2-3 days after removal of the trifoliate forage, the sores dry up & heal. While not common this condition may be severe and is therefore worth noting.

[C] The inclusion of herbs that broaden a horse's diet [e.g.. wild garlic] is considered beneficial; thus a hay lacking in herbs may not provide the best possible forage for the horse. However it may in certain cases be helpful to have a straight monoculture hay. For example, when tracking down possible allergies.

[D] Fescues are commonly used to give "bottom" to a sward & to increase its drought resistance, however, high levels of Fescue encourage an increase in its associated parasitic fungus, Epichloe Typina. This is toxic to horses, if eaten. Its mode of action is two fold; firstly it depresses the release of prolactin, thereby inhibiting mares in their production of milk. Furthermore, it also produces a chemical, Chonoclarine I, this depresses levels of cortisol and inhibits mammary gland development. Thus foals can suffer or even die due to lack of nourishment from their mothers.

[E] Photosensitisation has also been noted due to Aslike clover being fed, particularly in areas with high copper or selenium levels. Aslike contains a toxin which damages the liver so that it does not drain correctly into the intestinal tract. The obstruction causes the metabolic by-products of chlorophyll to build up in the bloodstream. When exposed to light in the less pigmented areas of a horse e.g.. a white sock , the activated residues cause skin cells to die in large numbers.

[F] Alfalfa & certain clovers have oestrogenic activity, there is no specific evidence that this causes problems, however it is possible that high levels may be associated with abnormal oestrus in mare's breeding cycles.

[G] Where home production of a conservation crop is to be practised, it should be noticed that care must be taken with artificial fertilisers. High levels [partic. of Nitrogen fertilisers] have been noted to cause metabolic disorders in grazing horses. It is also suspected that high nitrogen levels in forage may adversely effect the development of bone in young horses. Having decided upon which fields to conserve pH should be considered.


The pH of ones soil will effect which grasses are most successful at growing on your land, see table 4 below.

Forage Variety pH *
Cocksfoot 5.30
Fescue 4.70
Ryegrass 4.70
Timothy 5.30
Lucerne 6.20
Sainfoin 6.20
Trefoil 6.10
Vetches 5.90
Clover, Aslike 5.70
Clover, red 5.90
Clover, wild white 4.70

* Below this pH growth is restricted.

Control of species within the sward may be assisted by pH control, such as the addition of lime to the land.

Feeding Characteristics

A brief comment about hay & equine nutrition. As the general level of physical performance required from a horse increases then so should the energy density of the horses feed ration. This normally means a move away from hay, towards concentrate. The following table demonstrates typical energy & protein requirements of a 500kg Thoroughbred mare, daily.

Table %
Activity MJ of DE Kg of DP
Maintenance 62 0.3
Pregnant [B-90days] 72 0.37
Lactating 130 0.87
Eventing 112 NA
Racing 150 NA

DE = Digestible Energy - DP = Digestible Protein

An adult horse requires between 7 & 8.5% Crude Protein per day and can thus receive his entire quota from hay. However due to the high energy levels required by a performance horse, much protein is actually supplied by the concentrate and hay @ 7% CP is quite sufficient.

Contrastingly the lactating broodmare & the growing foal will need higher levels of protein, as above and in general :

Foals: 18% CP dropping to 16% CP @ 6 months

Weaned foals : 16% CP dropping to 13.5%CP @ 1 year

Yearlings : 13.5% CP dropping to 10% CP @ 2 years

Initially the CP is provided by concentrate since the foal cannot consume large quantities of hay, but by 2 years of age most can be supplied by a suitable high protein hay. Thus referring back to Table 2 one can select the correct sward type according to the requirements of the stock to be fed.

If looked at in slightly more detail then; on a Dry Matter basis yearlings require 0.4% Phosphorous at a Ca to P ratio of 1.7 : 1. This is similar to the requirements of lactating broodmares. Now compare back to table 2 again; it should become clear how Legume/grass mix hays may provide a good balanced basis for the diet of many stud horses. Also note how partly conserved ryegrass hay could be used as a substitute {its DM content of circa 55% is slightly drier than that of haylage hence the term "part conserved"}.


Horses performing via physical endeavour will perform quite acceptably when fed on top quality meadow hay though I would in preference choose an Italian ryegrass / Timothy mix. In selecting a meadow hay particular attention should be paid to the actual grass varieties within the crop a mixture of ryegrasses and meadow grasses with some clover being typical of a good example. However, Broodmares & youngstock could benefit from receiving a different type of hay from the competition horses above. Grass / Legume mixes are traditionally the most suited however the use of partly conserved forages must also be seriously considered. Below are two typical seed mixes {by weight} to provide a good quality multipurpose sward for both equine grazing & conservation.

Mix A 50% late perennial ryegrass - multiple varieties 25% standard perennial ryegrass 10% Creeping Red Fescue 5% each - Crested Dogstail, Rough Stalked Meadow Grass, and herb mix incl. white clover

Mix B 20% Italian Ryegrass 20% Hybrid Ryegrass 20% Tetraploid Perennial Ryegrass 10% Late Variety Ryegrass 15% Creeping Red Fescue 10% Timothy 3% General Herb mix 2% Wild White Clover


Pasture Management - Gillian Mcarthy
Equine Nutrition - AC Leighton Hardman
Horse/Stable Management - J Houghton-Brown & V Powell-Smith
Equine Injury & Therapy - Mary Bromley
Nutrient Requirements of Farm Livestock - various
The Thoroughbred Breeders Association
M Archer - Equine Research Centre
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Updated: October 2005.