Roughage

FIBRE

Good equine health begins with a well-functioning gastrointestinal tract. For healthy digestion, a horse needs a daily intake of fibre. But what does fibre actually do? What is the relationship between fibre and the microbiome? And does every horse get enough fibre? In this article, Dr Erica Reijerkerk, a veterinary surgeon and specialist in equine internal medicine, tells us all about fibre, explaining why it’s important and what happens as it passes through a horse’s body.

ERICA REIJERKERK GRADUATED FROM THE UNIVERSITY OF UTRECHT IN 2004 WITH A DEGREE IN VETERINARY SCIENCES SPECIALISING IN HORSES. SHE THEN ATTENDED THE FACULTY OF VETERINARY MEDICINE IN UTRECHT FOR THE ECEIM SPECIALISATION IN EQUINE INTERNAL MEDICINE. ALONGSIDE HER WORK AS A VETERINARY SURGEON AT THE HOFSTEDE EQUINE CLINIC AND REHABILITATION CENTRE IN LEUSDEN, SHE IS AN EQUINE FEED CONSULTANT AND A SPECIALIST LECTURER IN EQUINE HEALTH, AND TEACHES AT VARIOUS EDUCATIONAL INSTITUTIONS FOR EQUESTRIAN SPORTS AND MEDICINE. There are many types of fibre. When we speak about it in the context of horses, we are really talking about the fibre found in feed. This is a collective term for a large group of carbohydrates that are fermented by bacterial conversion. Fibre in feeds primarily comes from plant materials. Being herbivores, horses are fibre eaters par excellence. Fibre consumption not only delivers needed energy, its conversion and its very presence in the gastrointestinal tract promotes good health, both directly and indirectly. In addition, fibre plays an important role in stimulating the motility of the gastrointestinal tract (faeces) and the body’s natural defences.

Generally, it can be said that fibre’s influence and its numerous functions make it an essential “universal tool” for a well-functioning gastrointestinal tract, leading to the absorption of important nutrients and a strong immune system.

The gut microbiome

In and on the body live many microorganisms including bacteria, viruses, and yeasts. These are known collectively as the microbiome. It is a versatile system that plays an important role in both digestion and immunity. In recent years there has been increasing scientific interest in the microbiome and its connection to health. However, it is still difficult to properly illustrate this system. Many individual differences are observed in the populations of microorganisms, and their composition also depends on many (external) factors. The composition of the gut microbiome can be influenced both positively and negatively. High-quality, high-fibre feeds support the development of a stable and healthy microbiome. Stress or, for example, antibiotics will have a negative influence on gut flora and cause digestive problems which can result in diarrhoea or colic.

Happy gut flora

We want to keep the gastrointestinal tract’s inhabitants (gut flora) happy. Prebiotics is a collective term for “nourishment” for good bacteria, so that the latter can perform their job well. Fibre is the most natural type of prebiotics and supports the growth and function of beneficial gut bacteria. Fibre is present in grass, hay, lucerne, and silage (haylage) and can also be found in small amounts in concentrate feeds. For example, beet pulp, wheat, spelt, bran, and grain heads/husks are useful fibre sources that are often components of concentrate feed. Problems can arise if the horse is fed too little roughage daily, if the roughage is of

5 TIPS VAN ERICA REIJERKERK

Erica Reijerkerk is an expert on equine internal health. She has a few tips to share with you:

• Always give your horse sufficient quantities of fibre via forage and concentrate feeds, but unlimited access is not always the best. It’s better for a horse to get several portions a day that meet its energy needs. • The first step in the digestive process involves the teeth. Annual dental check-ups are highly recommended! • Sometimes it can’t be avoided – the horse needs a round of antibiotics. For the gut microbiome to recover more quickly, your horse needs fibre from forage, because this kind of fibre is the most natural form of prebiotics. • Exercise also influences digestions. Do you have an injured horse on box rest? Then feed him low-energy, low-fibre feed and watch for impactions. • Monitor your horse every day by looking him over for any signs of poor health. How do his droppings look, and how much is he producing? • Does your horse eat well? Is he drinking enough (at least 30 litres every day)? • How does his coat look, and what is his Body Condition Score?

poor quality, or if the horse cannot consume enough feed due to dental or digestive problems. Horses with motility problems in the gastrointestinal tract may experience excessive feed volume, leading to impaction. It is therefore important that the horse gets sufficient exercise to promote intestinal motility. However, it is important to know that not every horse is suited to ad libitum forage intake. Much depends on the hay’s nutritional profile. Excessive consumption of young grass or nutrient-rich hay means that the horse is also consuming more sugar and protein. In some cases this can lead to digestive or metabolic problems like obesity and laminitis. Therefore, the type and amount of daily forage should always be adapted to your horse’s needs.

Two types

Fibre in forage and fibre mixes fall into two categories: fermentable and non-fermentable. Fermentable fibre is broken down by bacteria in the small and large intestines and converted into volatile fatty acids, delivering energy. Non-fermentable fibre normally delivers no energy and therefore appears to have no use. But that’s not true. Non-fermentable fibre gives the contents of the gut more volume and stimulates the intestinal walls to “knead” it, thus influencing the feed’s speed of passage. The combination of kneading and passing at the right speed ensures a good mixing of the contents in the gut and longer contact of the chyme with the intestinal wall, promoting the absorption of nutrients.

Structure

Next to fermentability, structure is also important – namely, whether the fibres are long or short. “Stalky” forage is important as it stimulates chewing. Chewing is the first step in digestion and helps to chop up the feed particles and stimulate saliva production. You might look at this part of the digestive process as a present. You have the feed components (the packaging), but you can’t use the contents of the present if you can’t unwrap it. Digestion means nothing other than making nutrients accessible and processing them (breaking them down) so that they can be absorbed by the body. The first step, then, is to provide high-quality roughage with the right structure and the right components. Also important are well-functioning teeth and a well-functioning gastrointestinal tract so that the right nutrients get to where they are needed in the horse’s body.

Faeces as indicator

Naturally, it is difficult to give a 100% reliable estimation on how much fibre a horse consumes. The horse’s droppings can provide some information. Are they quite dry, smelly, or watery? If they have a very coarse structure, this can tell you something about the horse’s teeth, but also about the health of its gut flora. A disturbed gut microbiome cannot adequately digest fibre. Here, prebiotics or probiotics can help. Colic and diarrhoea also arise in connection with fibre consumption. The solution is feed with sufficient fibre based on a high-quality forage. Roughage – fibre – is the driver for the motor that moves the horse. Nutrient requirements that cannot be met with forage can then be replenished through concentrates and feed supplements.

Practical experience

Dr Erica Reijerkerk sees many horses with feed-related ailments such as emaciation, colic (including stomach ulcers) and diarrhoea. She moves through several steps to find out the cause of the problem before deciding on a treatment. After taking a close look at the horse’s circumstances as well as its feeding plan and feeds, she makes a clinical assessment that includes body weight and body condition score. “Then I do a rectal examination. I palpate the organs and bowel walls and assess the location, degree and appearance of the bowel contents. And then I examine the faeces. Additional ultrasound examinations and blood tests can also help determine the cause. I normally check the blood for inflammation levels and the protein fractions. If, say, the blood work reveals low protein levels, they may be due to a deficiency or increased requirements, or it may be a problem with protein absorption. Step by step, we get to the heart of the problem. A gastroscopy may be necessary as it isn’t possible to see from the outside whether the horse has a stomach ulcer. This also allows you to examine a section of the intestinal wall. A functional test can tell us whether the small intestine can absorb sufficient nutrients.”