Grass and other forages

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Pasture

Pasture is the best place for horses to live because it allows them to express normal behaviour and eat a normal diet. Whole plant material is what horses have evolved to eat, and they are healthier if their diet reflects this. However! much of our UK pasture is not ideal for horses because it oversupplies nutrients during spring and summer. Consider the growth chart below, which gives a guide to grass yield from pasture. Such oversupply means that for many horses, pasture access will need to be restricted. It can also become too poached in winter, which is unhealthy for both the pasture and the horses on it.

UK spring and summer grass can cause problems for horses and ponies due to it being too high in calories (energy) and the non-structural carbohydrates fructan and sugars. These excesses cause weight gain and an increased risk of laminitis in susceptible horses and ponies. 

Typical grass growth throughout the seasons

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Nutrient content of pasture grass

The protein and energy content of grass varies considerably with the season, but in spring and early summer grass may contain up to 20% protein and 11MJ DE[1]/kg – equivalent to a competition feed! Coupled with this nutritious profile, it is very palatable and easy for horses to eat, and given ad lib access they may eat much more than they would of conserved forage, therefore being oversupplied with nutrients.

For horses, grass is a rich source of vitamins and usually, the minerals calcium, phosphorus, magnesium, potassium, iron, manganese and cobalt. Sodium is likely to be in short supply for horses, as are the microminerals zinc, selenium and copper, and sometimes iodine too. However, mineral content can vary and if in doubt, the herbage should be analysed.

The table below shows normal ranges of mineral content of pasture grass in the UK (1 kg dry matter (DM)).

Adapted from P McDonald et al (2002) Animal Nutrition. 6th ed., Pearson Prentice Hall

Pasture needs good care if it is to be a food source because horses are very selective grazers who will not eat grass in their latrine areas (where they urinate/defaecate or poo). Ideally:

• Pick up droppings regularly, although it may be worth leaving certain patches as latrine areas to encourage horses to manure in these areas. These ‘roughs' will need to be cut and rested or grazed with other species
• Watch grass growth carefully, perhaps by fencing off a small ungrazed area so that the yield of grass is not underestimated due to horses eating all the new growth
• Take advice on management including fertilisation, reseeding, harrowing, rolling
• Control poisonous weeds e.g. ragwort

If horses or ponies get too fat on pasture, or are prone to laminitis, they will need to have their pasture access restricted. There are a variety of ways to do this but the main two effective ways are:

1. strip grazing (the back may need to be closed as well as the front opened, to restrict grass intake enough)
2. grazing muzzles 

Consider a track system (e.g. Jaime Jackson's Paddock Paradise), allowing pasture to be maintained for preserved forage whilst horses live on a less grassy area where they are encouraged to move more. Grass free (or mostly grass-free) tracks work best. Warning! Do not assume that grass track systems will restrict grass intake enough in good doers. Monitor the individual horse or pony and adjust grass access accordingly. 

Conserved forages

Hay or haylage are often more suitable forages than pasture grass, especially for overweight horses and ponies, and many ponies. Both conserved forages are processed when more mature than the type of grass horses usually graze, so are more fibrous and lower in energy and protein.

Do not disregard straw as forage, providing the horse has good dental function and access at all times to water. Introduce gradually and feed a maximum of a third of the total forage ration.

Note the following:

• Ideally, all UK made hay should be soaked or steamed before feeding due to its mould spore and dust content – half an hour is the maximum necessary for hygiene and 10 minutes might be sufficient
• Soaking hay reduces its calorie and sugar content, so is useful for overweight/laminitic horses and ponies – it may need to be soaked for 10-12 hours to reduce feed value enough (but check initial WSC[2] content with analysis and ideally WSC content after soaking)
• Haylage is superior to hay from a hygienic point of view because it is ‘pickled' with moisture levels maintained so mould spores should be low or absent
• Late cut high fibre haylages may be suitable for overweight/laminitic horses and ponies and may be lower in WSC than early cut hay (but calorie content could still be too high, so monitor the individual)
• Hay and haylage lose vitamin E and A and may lose minerals during the preservation process, so must be supplemented with a multi-vitamin and mineral supplement, balancer or feed
• Hay/haylage can be analysed for NSC content to assess suitability (NSC is non-structural carbohydrates, but often ‘water soluble carbohydrate' or WSC is used because UK grass contains consistently, little starch).
• For challenging cases, always analyse forage (but be aware that analysis is only ever representative and therefore is a ‘best guess')

Quick-dried forages can be useful to upgrade poor forage – add 1-3kg quick-dried alfalfa or grass to the ration (for a 500kg horse – adjust according to bodyweight). These forages can be in chopped form (chaff) or in ground, pelleted form, which need to be soaked before feeding.

Hay replacer chaffs are useful products that can be used to replace regular hay or haylage, and/or for mixing supplements into for horses and ponies with low energy requirements. They include later cut grass chaff, pellets and cobs, and mixes of straw and either quick-dried alfalfa or grass, with molasses/vegetable oil coating. Some contain vitamin and mineral pellets and can be used as a total feed.

A huge number of different types of chaffs are available nowadays, in bags or in compressed blocks. Check their suitability for use as a hay or haylage replacer – for example molassed chaffs (usually 60% chopped straw + 40% molasses) are not suitable to replace forage.