A horse’s taste preference is determined by many factors, such as the taste and texture of the food, all of which help to prevent him eating toxic plants.
In addition, taste preference is affected by what we call post-ingestive feedback. The horse’s digestive tract, including the liver, sends signals to his brain about which nutrients he requires. This sensory system can determine whether these nutrients are available in the food the horse is eating.
A horse will also assess food visually, based on shape and colour and also by smell, which allows him to recognise different foods.
It would seem that horses eat when they are hungry and drink when they are thirsty, with little nutritional wisdom other than selecting high-calorie feeds. If given free choice over a range of feeds, for example, they are unlikely to choose the healthiest and balance their intake of nutrients. They are known as selective grazers, however, which means that they will select edible forages and avoid toxic plants.
So how does a horse experience taste? Tiny sensory organs in his mouth, called taste receptors (similar to our taste buds), send signals to his brain. It seems that horses prefer sweet and salty tastes.
Scientists have shown that a horse appears to react differently to sweet tastes compared to bitter ones, nodding his head, moving his ears forward and licking his lips when given a sweet feed. When given a bitter-tasting feed, however, a horse tends to curl up his lips, move his ears backwards and stick out his tongue.
These reactions to sweet and bitter tastes are the same in many other species, including humans. Sweet receptors are located on the tip of the horse’s tongue — his response to sweet tastes is licking, which moves the sweet feed into his mouth. Bitter receptors are located towards the back of the horse’s mouth and his response to a bitter taste is to push the feedstuff back out of his mouth.
These reactions to different tastes are most likely to have evolved to help horses survive by selecting sweet-tasting, high-calorie feedstuffs over toxic plants, which often tend to taste more bitter.
Variety: the spice of life?
As humans, we have large variations in individual food preferences. Some of us have a sweet tooth yet others prefer something salty or spicy, while different people have a strong like or dislike of specific vegetables.
Horses, however, do not tend to have the same diversity in food preference; their taste preferences are aimed principally towards intake of calories for survival.
Free-ranging horses will typically browse over many different forages and may consume more than 50 different plant types on a daily basis. By contrast, domesticated horses are generally provided with one forage type.
When offered either a single forage or a choice of several different forages, horses do appear to prefer access to multiple forage sources. It is thought that this may be because in the wild, the nutritional value of a food source is constantly changing due to a whole host of environmental factors.
Horses have therefore developed the ability to select feeds based on their nutritional content. Changing selection of forage throughout the year means that energy intake is maximised as they can self-select the forage with the highest energy at that particular time.
Having said that, horses do not get bored eating the same thing every day. They are not like humans, who actively seek out and enjoy new tastes; they prefer to eat what they are used to.
In fact, horses do well on a relatively consistent forage-based diet. This is essential in terms of keeping their gut healthy and minimising the risk of issues such as colic. Any changes to your horse’s diet should therefore be made very gradually to avoid digestive upset, ideally over a period of two weeks.
We all know that our horses like carrots and mints, but who would have thought that they may prefer banana and fenugreek?
This may seem surprising, yet horses in India are frequently fed bananas — and working animals in the UK were often given fenugreek to encourage them to eat their feed. The feed industry uses flavours such as mint, garlic and apple in their feeds to increase palatability. Adding flavour is a good way of ensuring that horses eat their supplements, so manufacturers have begun to include banana and fenugreek in these.
Flavour can also be used to mask the taste of medicines and to encourage horses to take certain medicines. Getting your horse used to enjoying the odd syringe of sweet apple sauce (sugar-free, if possible) can mean that future de-worming is a less traumatic experience for both of you.
Illness can have a profound effect on appetite. Loss of appetite can be incredibly difficult to manage and willingness to eat is hugely important for a horse’s recovery.
Using flavours to encourage sick horses to eat is an interesting area, but has received little attention by way of research. Some studies have been undertaken involving horses with chronic grass sickness, where a decrease in appetite is commonly seen, using different flavours to increase feed intake.
Similarly, many horses have a markedly depressed appetite following colic surgery. Some equine hospitals have seen clear improvement in the appetite of their patients when they add certain flavours, including ginger, to meals.
More research is needed, however, to establish clear evidence and guidelines for the use of flavours for different medical or post-surgical management.
Ref Horse & Hound; 19 January 2017