Katie Grimwood BSc Hons, nutrition advisor at Baileys Horse Feeds, talks us through how to help our horses transition to the spring grass
Most people would not dispute that grass is the most natural feedstuff for horses. However, for many horse owners, their paddocks are more a means of giving their animals a leg stretch than for supplying a nutritious meal, especially over the winter months when grass availability and quality may be more limited. Come the spring however, grass pasture will usually become a much more prominent part of our horses’ diets.
Throughout the year, grass growth is regulated by the weather and the nutritive status of the soil in the paddock. In the UK we generally have a flush of grass in the spring, which can be as early as February, if the conditions are right. Maximum growth is between May and early June, followed by a slump in summer and then a further autumn flush usually, between August and September, although in the right conditions, growth can re-occur right into October. This seasonality of grass growth also affects how digestible or nutritious the grass is at certain times throughout the year; while many of us eagerly anticipate the appearance of the spring grass, and the benefits it brings, for some horses, it can be too much of a good thing!
During rapid growth in the spring, the fibre content in the grass is lower and is more easily digested by the horse. Although this is beneficial in that the horse can extract the nutrients from the grass more easily, it can also disrupt the microorganisms in the horse’s hindgut. Fibre is important in maintaining gut microbial health and, a lack of fibre could cause a disruption. Combining this with the higher moisture content at this time of year, it is unsurprising that some horses become loose in their droppings, when turned out on spring pasture. A sudden change onto fresh grass can also increase the risk of colic.
For this reason, it is important to introduce access to spring grass gradually, especially when the horse has been predominantly stabled or on very limited grass through the winter. Transitioning from a “winter field” onto a “summer field”, which may have been rested for several months, should also be done slowly. Ideally, this change should be made gradually over two to three weeks, starting off with one hour and increasing turnout time on the fresh grass a little more each day. Supplementary hay and/or haylage should also be continued during periods away from the new grass.
Using a prebiotic before, during and after this transition phase can also be worthwhile, especially for horses that are particularly sensitive. Prebiotics help to support the efficient functioning of the horse’s hind gut by helping to maintain the balance between beneficial and harmful species of hind gut bacteria so, can help to reduce the incidence of digestive disturbance and loose droppings.
Changes in nutrients
Spring grass is rich in energy and protein – hence why horses tend to hold weight and condition much better at this time of year. This means that it is usually ideal for poor-doers or those that have lost too much weight over the winter. Grass will typically provide more quality protein than hay or haylage, which is why we can tend to struggle more with muscle development and maintenance of muscle condition over the winter months or for those horses that are stabled more. For good-doers however or, those that are overweight, access to grass turnout in the spring and summer may need to be more restricted, whether that be through reduced turnout times, strip grazing or the use of a grazing muzzle. Body condition should be monitored by regular body condition scoring, weightaping and taking photos of your horse, to help identify fat loss or fat gain and determine if any forage and management changes are required.
While the energy and protein content in grass will typically be consistently elevated, in the spring, the vitamin and mineral status of grass can vary greatly and rarely supports the requirements of the horse. For this reason additional supplementation in the form of a pelleted forage balancer, is usually recommended for good-doers to help ensure their nutrient requirements are being met, without extra calories.
Higher levels of digestible energy in spring grass can not only contribute towards weight gain but, may also result in more excitability or fizziness. Spring grass will also typically have a higher sugar and fructan content and, when an overload of sugar is consumed, which is easily done on an abundance of spring grass, this may also result in changes in behaviour. In simple terms, feedstuffs that are high in sugars or starch, such as spring grass or cereal grains, can sometimes be associated with causing over-exuberant behaviour, as starch and sugar are the main sources of “quick-release” energy in the diet. For horses that can be very fizzy or excitable on spring grass, it may be necessary to restrict turnout while the sugar levels are at their highest, and supply less nutritious hay or haylage to provide adequate fibre for correct gut health.
What about laminitics?
For those with a history of laminitis, the appearance of spring grass presents even more of a challenge – trying to balance limiting their sugar intake, while allowing them a chance to get outside and move around. When managing a horse prone to or, with a history of laminitis, there are a couple of additional considerations to think about once the spring grass starts to come through.
The component in grass that is thought to be responsible for laminitis is fructan. Typically, cool temperatures (5-10°C) will produce much higher fructan levels in grass than warm conditions (11-25°C), which is why laminitis is classically a spring and autumn problem. If the temperature is below 5°C, grass does not grow, however, if light is available, it can still produce sugars, therefore cold, bright conditions can result in increased levels of fructans.
Levels tend to rise during the day, peaking in the afternoon to early evening but, decline in the early hours of the morning. Therefore turning out very late at night or very early in the morning and, bringing in by mid-morning is thought to be the safest time for turnout. An exception would be if the grass was frosty in the morning; then the grass will not be able to use the sugars for growth so they will be retained and accumulate – turning out in such circumstances should therefore be avoided. Grass sugar and fructan levels can vary significantly, depending on factors such as sunlight, temperature, grass species and fertiliser application so, it is important to be cautious when introducing turnout for the laminitis-prone horse.
During periods of grass growth or increased availability, grazing may need to be restricted. It is important to monitor grass intake carefully and restrict grazing with strip grazing or even turn out on a bare paddock with hay provided. It should be noted that horses should not be turned out on large, overgrazed paddocks without supplementary forage, because stressed grass may contain relatively high levels of fructans and sugars. With regard to restricting grazing, more recent research has shown that limiting the amount of grazing time by only allowing a few hours of grazing per day and stabling the rest of the time is not as effective as once thought - horses seem to get used to the shorter grazing time and therefore consume more within this time to compensate for the limited availability! As such, it may be more successful to offer strip grazing to limit grass intake while also promoting movement and exercise.
So, while the benefits of spring grass are many, care should be taken to ensure its safe introduction or adapting your horse’s diet and ongoing control may be required for some, to ensure they remain happy and healthy, throughout the summer.