The most natural food

[Grassman]

The grasses available to most horses and ponies in todays modern, improved pastures are very different from the forage available to their not so distant 'wild' ancestors. As free roaming grazers they would have had access to a wide range of herbage and been free to move on to new grazing once an area was exhausted. Their grass would have been high in fibre and had relatively low nutritional content. Yet we continue to question whether todays rich, fertilised pasture grass can possibly be the cause of digestive problems.

Horses are selective grazers who pick out what they like to eat. The aim is to meet the needs for grazing requirements without the production of over-rich grass which could result in obesity and/or laminitis. So what is the feeding value of grass?

From a nutritional point of view, grass consists of two main parts, cell wall and cell contents.

1. Cell wall: This consists of lignin - a woody indigestible component - which gives rigidity to the plant and increases with maturity, plus the fibrous components of complex carbohydrates - including digestable cellulose and hemicellulose.

2. Cell contents: Proteins, fats, soluble carbohydrates such as sugar, starch, and fructans, and vitamins and minerals - all highly digestible and nutritious but which reduce with maturity.

The actual feed value of grass depends on its type, its stage of growth and to a certain extent the type of soil on which it is growing.

Types Of Grass

Grass species vary in their nutritional content and palatability. Ryegrass and meadowgrass are highly productive, palatable and digestible, whereas cocksfoot has a lower digestibility and is less palatable (but becomes clumpy in a sward).
An ideal horse pasture would contain over perennial ryegrass, meadowgrass and smaller proportions of timothy, bent grass, fescue and herbs. The older and less improved the varieties the better. Species which resist wear, such as creeping red fescue, help the land resist poaching.

The Growth Factor

Young, leafy grass is higher in cell contents and therefore has a higher feed value per kilo than mature, stemmy grass which is higher in cell wall (fibre).
Young, succulent grass is also easier to ingest and takes less time to chew due to its lower structural (fibre) content.

However, young grass can cause problems as it is higher in soluble carbohydrates and lower in fibre than more mature grass, which means,

1. Less fibre for the beneficial micro-organisms within the horse’s hindgut to feed on.

2. A higher risk of an overflow of soluble carbohydrate into the hindgut which leads to a proliferation of less beneficial acid-producing bacteria and hindgut disturbance - which may result in discomfort, colic, and/or laminitis.

Modern varieties of grass now common in UK pastures accumulate fructans as their storage carbohydrate with much greater efficiency.
Fructans are the complex sugar-like compounds which are thought to be involved in the onset of laminitis if ingested in large amounts by susceptible horses and ponies.
Unfortunately it is very difficult to predict the exact level of fructans present in grass at any point in time because this is dependant on environmental conditions, although levels are generally thought to be lower in older grass varieties, particularly diploids.

Measuring Munches

So how much does a grazing horse eat? One study found that horses ate 12.00kg of dry matter whilst grazing short grass and 10.50kg of dry matter whilst grazing grass at hay making stage, during a 24 hour period. This illustrates how intake goes down with increased grass maturity (hence fibre content).

In another study, horses turned out to pasture for seven hours ate 5.5kg of dry matter. Horses generally eat around 1kg dry matter grass per hour, which equates to 4.5kg fresh weight of grass (this includes the water content, which is about 80%)

With the correct grasses, herbs and good management a pasture can supply quality forage more akin to the grazing of ancestral roaming horses, so why not fully utiilise the most natural feed of all for your horse?