Feeding the picky eater
Professor Jo-Anne Murray
PhD, MSc, PgDip, BSc (Hons), BHSII, RNutr, PFHEA University of Glasgow Veterinary School
Do horses prefer certain foods?
A horse’s preference for certain foods is determined by many factors such as smell, taste and texture of the food, all of which help to prevent them from eating toxic plants. Taste preference is also affected by what we call post-ingestive feedback where the horse’s digestive tract, including the liver, sends signals to the brain about what nutrients the horse requires and can then determine whether these are available in the food that the horse is eating. Horses can also assess food visually based on shape and colour and as well as by smell, which enables them to recognise different foods. From what we know, it seems that horses eat when they are hungry and drink when they are thirsty, with little nutritional wisdom other than selecting high-calorie feeds. For example, if given free choice over a range of feeds they are unlikely to choose the healthiest feeds and balance their intake of nutrients. However, horses are known as selective grazers, which means they will select edible forages and avoid toxic plants.
Horses seem to prefer sweet and salty tastes. Scientists have shown that horses react differently to sweet tastes compared to bitter. Horses nod their heads, move their ears forward and lick their lips when given a sweet feed, and when given a bitter tasting feed they tend to curl up their lips, move their ears backwards and stick out their tongues. These reactions to sweet and bitter tastes are the same in many other species, including humans. There are sweet receptors on the tip of the tongue and the response to sweet tastes is licking, which moves the sweet feed into the mouth. Whereas, the bitter receptors are located towards the back of the mouth and the response to a bitter taste is to push the feedstuff back out of the mouth. The purpose of these reactions to different tastes is most likely to have evolved to help horses survive by selecting high-calorie feedstuffs (sweet tasting) over toxic plants, which often tend to taste more bitter.
Do horses need a varied diet?
As humans we have large variations in individual food preferences, some of us have a sweet tooth, whilst others may prefer salty or spicy, and like or dislike 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. Therefore, no matter how hard you try you won’t be able to get a horse to develop a taste for sushi! Free-ranging horses will typically browse over many different forages and may consume over 50 different plant types on a daily basis. In 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. So, it seems horses have developed the ability to select feeds based on nutritional content. By eating different types of forage throughout the year it means that wild horses can ensure energy intake is maximised by selecting the forage with the highest energy at that time of year.
Having said that, horses don’t 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, which is essential in terms of keeping their gut healthy and minimising issues, such as colic. Therefore, any changes to your horse’s diet should be done very gradually to avoid digestive upset, ideally over a period of 2 weeks.