Nutritional management of forage intake to maintain health and performance in horses and ponies
By Lizzie Drury MSc Registered Nutritionist of Saracen Horse Feeds
It is well established that forage remains one of the most important components in the diets of all horses and ponies irrespective of their life stage or level of exercise.
Forage not only contributes to the overall supply of energy and nutrient content of a horse’s ration but a supply of forage is essential to the healthy function of the equine digestive tract, through the physical movement of food through the gut, retention of fluid within the digestive tract and the protective effect of the microbial balance within the hindgut.
Forage should ideally be fed on an ad-lib basis, which means that it should be available at all times. Where this is not possible, long forage should be fed at least NO less than 1.0 % of bodyweight e.g. 4.5kg of long forage daily for a 450kg pony. For haylage, where the dry matter may range from 60-75%, a higher intake of 1.5% ‘as fed’ is recommended as being the absolute minimum.
Many causes of weight loss and behavioural issues can be related to below optimum forage intake. It is a good idea to find out how much forage an individual horse is eating to ensure optimum intakes.
For a few days, weigh the daily forage allocation and any that is left over. If there is none left over, then you may not be feeding enough, especially if the horse is losing weight. If there is still plenty left over and your horse is losing weight, then you need to find alternative methods of increasing fibre intake. Do not simply make up the deficit by feeding more concentrate feed!
Recent work has sought to dispel the view that forage is just gut fill and something to keep the horse occupied. Research has shown that good quality forage is able to maintain the bodyweight and meet the energy demands of Standardbred horses in heavy training with the energy demands of two times maintenance, over a 2.5-year period (Ringmark et al. 2012).
The protein content of many UK forages is low in low biological value and much of the protein present is locked up within lignified cell walls, rendering it unavailable to small intestine digestion and thus unavailable for anabolic purposes.
However, gut partitioning studies have revealed that some forages e.g. red clover silage and alfalfa are 50% digested within the small intestine making them good sources of protein (Moore-Colyer et al. 2005). When preparing rations for horses it is recommended that the amino acid profile is established rather than protein content per se.
The physiological age of a forage will also influence its mineral profiles, so it is best to analyse forage for mineral content to determine if and what supplementation is required.
One of the major challenges when feeding stabled horses forage is the level of airborne respirable dust (ARD) that it produces. Both hay and haylage can present respiratory challenges.
The traditional method for reducing ARD is soaking for between ten and 30 minutes but this leaches valuable nutrients and increases the bacterial concentration by two to five times that are found in dry hay. These figures further increase over time.
A better way to reduce ARD and improve the hygienic quality of the forage is to high temperature steam. Research studies have shown that specifically designed steamers consistently improve the hygienic quality of a forage while maintaining the nutrient value (Moore-Colyer and Fillery 2012).
The practice of soaking hay to leach out water soluble carbohydrates (WSC) and produce a forage of less than 100g WSC/Kg DM [dry matter], as recommended by Harris and Geor 2010, for obese and laminitic horses is widespread.
Soaking hay, aside from the increased bacterial burden, also gives very variable results. Thus it is recommended that testing of the forage is done post soaking, which presents practical issues for the average horse owner.
A recent study by Moore-Colyer et al. 2014 has shown that maximum WSC loss can be achieved by soaking for nine hours, then steaming the post soaked hay in a high temperature steamer.
The traditional fibre sources - grass, hay and haylage - have been joined in recent years by alternative products that offer fibre in a chopped, cubed or shredded form.
These alternative fibre sources are considered ‘super fibres’ because they have energy levels much higher than typical forages. The energy levels in super fibres are slightly less than those found in cereals, such as oats and barley, but they are safer to feed to horses than lots of cereals because their fibrous nature reduces the likelihood of starch overload.
Two popular super fibre sources include sugar beet and soya hulls. These feeds are more digestible than traditional fibre sources. For instance, hay is 40 to 60% digestible, depending on its quality, and beet pulp and soya hulls are 80% and 75% digestible respectively.
Some performance horses also benefit from super fibres, especially those asked to perform at moderate speeds for long distances such as endurance horses.
In addition to being a steady energy source for horses, super fibres maintain intestinal health. Consumption of fibre can increase water intake, creating a holding tank of water and electrolytes in the hindgut (Meyer and Coenen 1989). This reservoir may prevent dehydration and electrolyte depletion during an exercise bout.
Forage and super fibres significantly help with the nutritional management of gastric ulcers.
Ulcers and colic
Allowing horses free access to pasture and feeding alfalfa or other high calcium or high protein forages may help to reduce the risk of gastric ulceration. When adding alfalfa chaff to the ration to increase its buffering potential prior to exercise, 100 to 200 grams per 100kg bodyweight is suitable. This also helps to increase saliva production and does not add to significant ‘gut fill’.
Optimum levels of forage and fibre in the ration help to reduce the incidence of colic by maintaining optimum digestive tract contractions and general digestive health.
Increasing the proportion of long stem forage and super fibres within a ration helps to reduce the reliance on cereals and starch and can significantly reduce the incidence of colic.
Supplementing the ration with live yeasts such as Saccharomyces-containing probiotics and ScFOS prebiotics helps to optimize forage digestion and utilization by the microorganisms in the hindgut.
Evidence to date shows that high forage diets support a more stable hindgut microbiome and thus promote digestive health in horses.