Mind the Hindgut

The horse has a highly specialised large intestine (caecum and colon), known commonly as the ‘hindgut’. Within the hindgut there are many billions of bacteria who live with the horse in a comfortable arrangement whereby the horse provides them with accommodation and they provide the horse with energy from fibre and a host of vitamins.

The hindgut environment is tightly controlled to allow the bacteria to thrive and do their job. High grain diets like those fed to racing horses can however quite easily upset the balance, causing mass deaths of beneficial bacteria and severely limiting hindgut functionality. The consequences of poor hindgut health can be as far reaching as weight loss to behavioural changes, poor hoof quality and loss of appetite. Needless to say, keeping the hindgut healthy is in your best interests if you want horses to perform at their best.

The hindgut and health

The hindgut plays several roles in the digestion of feed and in maintaining the overall health of a horse, including:

Fibre Digestion – horses don’t have the enzymes necessary to digest fibrous feeds like pasture and hay. However the bacteria in the hindgut are capable of digesting fibre via a process of fermentation, providing the horse with energy in the form of volatile fatty acids (VFAs). VFAs are a major source of fuel for muscles in racing horses.

Hydration and Electrolyte Balance – the hindgut and the fibrous material within it provide a reservoir of water and electrolytes for the horse which may be absorbed when needed to keep the horse hydrated.

Vitamin Supply – the bacteria that ferment fibrous feeds also produce vitamins including vitamin K and B-group vitamins like thiamine (vitamin B1) which is important for the maintenance of appetite and biotin which is critical for hoof growth.

Hindgut Acidosis – A truly messed up gut!

Hindgut acidosis describes a condition in horses where the pH in the hindgut becomes acidic. Diets that contain whole or cracked (uncooked) cereal grains like corn or barley deliver a lot of undigested starch to the hindgut. This starch is rapidly fermented by a small population of bacteria (amylolytic bacteria), resulting in an accumulation of VFAs and lactic acid and a condition known as hindgut acidosis.

A survey published in 2006 (Richards et al.) found that more than one quarter of racing thoroughbreds have hindgut acidosis. Even though it is a common disease that will severely limit racing performance, because its symptoms are often subtle, it is not well recognised in racing horses.

Acidic Hindgut = Unhealthy Horse

Hindgut acidosis has many negative implications for racing horses, including:

Reduced fibre fermentation – Fibres like hay and chaff are often thought of as ‘fillers’ for the horse. In reality, these fibres supply an important source of energy, with around 40% of a horses daily calorie needs being supplied from the fermentation of fibre. The problem is, when the hindgut becomes acidic, the bacteria responsible for fermenting fibres become inefficient and eventually start to die, meaning fibres are no longer efficiently fermented and the horse starts to miss out on this source of energy. What this ultimately means is the horse will start to lose weight.

Vitamin B1 deficiency and loss of appetite – The bacteria responsible for causing hindgut acidosis also produce a compound called thiaminase which destroys vitamin B1 (thiamine). Vitamin B1 plays a critical role in maintaining appetite, so if a horse develops hindgut acidosis it will also commonly stop eating grains, preferring instead to just eat hay and chaff. This loss of appetite commonly results in the horse losing weight and needing a spell.

Biotin deficiency and poor hoof quality – hindgut acidosis also affects the production of biotin in the hindgut and limits the growth of good, strong hoof tissue. An acidosis induced biotin deficiency is likely to be a major cause of hoof problems in racing thoroughbreds.

Colic – In severe cases of acidosis a horse may experience colic. It is also common to see soft to sloppy manure that has a pungent, acidic, vomit like smell in horses with acidosis.

Altered behaviour – horses with acidosis will commonly exhibit some form of altered behaviour which may include being generally agitated, chewing on timber, eating their bedding or manure and licking at their stalls.

Endotoxemia and metabolic acidosis – If hindgut acidosis is severe enough, the wall of the hindgut becomes damaged by the low pH conditions, allowing endotoxins and lactic acid from within the hindgut to pass through the gut wall and into the bloodstream, lymph or the peritoneal cavity.

Laminitis – It is well known that hindgut acidosis can lead to the painful inflammation of the lamella in the hoof. While laminitis is well recognised in its acute form, it is possible for horses to suffer with chronic laminitis where only mild to almost undetectable lameness occurs. Chronic laminitis may be so mild it may just cause a horse in full gallop to shorten its length of stride.

Maintaining a healthy hindgut

If a horse’s hindgut is out of kilter the horse cannot possibly work and perform to the best of its ability. It is critical that you maintain the population of beneficial bacteria in the hindgut and avoid the fermentation of starch. To do this, there are two very simple rules to follow:

• NEVER feed uncooked corn or barley – The starch in corn and barley is very difficult for a horse to digest in the small intestine unless it has been cooked. Feeding corn or barley whole, cracked, crush, rolled or ground is going to mean that more than 70% of the starch contained in those grains will end up being fermented in the hindgut and causing acidosis. Corn and barley are excellent, high starch sources of energy for racing horses, but they MUST be fed cooked.

• ALWAYS feed enough hay and chaff – Racing horses should be fed at least 1% of their bodyweight in hay and chaff, which is 5 kg/day for a 500 kg thoroughbred (as a guide, one biscuit of lucerne hay will weigh close to 2 kg, a 2L dipper of chaff weighs around 250 grams). Feeding less than this starves the hindgut bacteria of fibre to ferment, upsetting the hindgut environment and limiting the amount of energy and beneficial vitamins supplied to the horse.

If you are concerned about a weight disadvantage from feeding this much forage, simply reduce the amount of hay and chaff fed for 2 to 3 days leading up to a race.

Feed the hindgut

When making any feed choices for racing horses you should always first consider the impact the feed will have on the hindgut. Because the hindgut is so critically linked to a horses overall health, keeping the hindgut healthy will give a horse its best chance at racing well. Mess it up and the horse will lose its appetite, lose weight and lose its ability to race at the level it is capable. Get it really wrong and you will lose the horse entirely to colic, laminitis or endotoxemia. And getting it right really is as simple as feeding cooked grains and plenty of fibre!

Dr Nerida Richards
Equilize Horse Nutrition Pty Ltd

With feeds and supplements to suit any preferred method of feeding, contact Pryde’s EasiFeed for a full assessment of your race feed regime. Call 1300 732 267, email info@prydes.com.au or go to feed selector.

Reasons why Pryde's EasiFeed is different

Only the best quality ingredients

When it comes to the ingredients we use in your horse’s feeds we are fussy (to say the least). Raw materials are specially selected, and once they arrive at the mill they undergo a series of tests to make sure they are up to our standard. Anything that doesn’t meet our tight specifications is sent back to where it came from.

Same high quality ingredients in every bag

At Pryde’s, each feed has its own set recipe that is used to make that feed day in, day out. This means you get the same high quality product in every bag of feed you buy. We don’t least cost mix any of our feeds.

Feeds are made in a dedicated horse mill

We place the highest priority on feed safety for your horses. To make sure nothing ends up in our feed that could hurt your horse, there are no drugs, antibiotics, ionophores, hormones or urea kept in the mill, so they can never end up in our feeds.

Regular feed analysis

we have our own in-house, high tech laboratory that is used to constantly monitor feed protein, moisture and water activity levels. Feeds are also regularly and extensively tested by an independent laboratory for protein, mineral and heavy metal content to make sure what we say is in the bags is actually in there and that there is no contamination with heavy metals.

Quality Assurance Programs

Pryde’s EasiFeed is a Feed Safe accredited mill, with all feeds being produced under the ‘Feed Safe’ code of good manufacturing practice.

Family owned and operated

Being a family owned and operated company, you will always get personal service with Pryde’s. And with the feeds carrying our name, we are dedicated to ensuring only the very best quality feed goes into our bags.

Customer Service

We are dedicated to supporting anyone who needs help with feeding their horse. So whether you have one horse or 100, if you need help we are only a phone call or an email away, try us.

Easy to digest

Research over the last 20 years has proven the benefits of extruding feeds for horses. Extruded feeds are super digestible, so they are used efficiently by horses, meaning you can feed less for a better result. They also eliminate the problems caused by feeding uncooked grains.

Protein, protein, protein

A major point of difference between our feeds and other feeds on the market is protein quality. Pryde’s EasiFeed uses premium quality protein from soybean supported by excellent protein from lupins and faba beans to give your horse the best possible proteins available. We NEVER use poor quality protein sources like cottonseed meal in our feeds.

Range

We have a feed to suit all horses and all budgets. If you are not sure which feed is best suited for your horse, give your local Pryde’s representative a call.

The Problem with Pasture

For anyone driving around the country at the moment it is evident that we have just had a wet summer, with green pasture in abundance. Pasture is a wonderful resource for thoroughbred breeders, providing energy, protein, vitamins, minerals and the all important fibre for broodmares and growing horses alike. Access to pasture also means the need to provide hay and ‘hard feed’ is reduced, taking pressure off feed bills. However pasture brings with it its own set of issues that need to be carefully managed to prevent structural issues in young stock and obesity issues in mares.

Too much of a good thing        

High quality pasture contains a lot of energy (calories). It is also palatable and if there is plenty of it, mares and young horses can easily eat enough to exceed their true daily energy requirement. For the mares, this means gaining weight and having issues with obesity. For young horses it means growing too quickly and potentially causing developmental orthopaedic diseases including OCD that are associated with rapid growth.

Hard feeds should be cut back

It is not easy to control a horse’s pasture intake and while you can use strategies like strip grazing to control calorie intake, the first thing that should be done in a situation where mares are getting too fat or weanlings and yearlings are growing too fast on high quality pasture is reduce the grain based ‘hard feeds’ being fed. This will help to reduce their overall energy intake and hopefully slow weight gains.

Pasture won’t meet mineral requirements

It is well known that a majority of Australian pastures don’t contain enough copper, zinc, selenium or iodine to support a broodmare or growing horse’s requirements. In many situations calcium and phosphorus are also below optimum levels and very occasionally manganese will be deficient. Under ‘normal’ pasture conditions, the hard feeds used in a diet (provided they are good quality feeds) fill these mineral ‘holes’ left by the pasture so that together the pasture and feed provide a diet that meets all requirements.

However, in a good season when the amount of hard feed is reduced or even removed from the diet to help control weight gain, horses are suddenly reliant on pasture to meet their nutrient needs and this WILL leave mineral deficiencies in the diet.

Use a balancer pellet

The simplest way to correct the mineral deficiencies that will be present in pasture based diets is to use a mineral balancer pellet. Balancer pellets are designed to fill the mineral holes left by pastures without adding excess energy to diets that would contribute to weight or growth rate problems. Balancer pellets will have a feeding rate of between 500 g to 1 kg/day and provided they are well formulated and fed according to the manufacturer’s directions will cover both a mares and growing horse’s needs for extra calcium, phosphorus, copper, zinc, selenium and iodine as well as a range of other minerals and vitamins.

Test your pasture

While we know most pastures will be deficient in the minerals discussed above, pastures, depending on where and how they are grown, often have their own unique issues that can cause problems with the sound growth and development of weanlings and yearlings. These issues can include:

• More phosphorus than calcium – it is increasingly common to see more phosphorus in a pasture than calcium. When this is the case the phosphorus blocks the absorption of calcium and creates a calcium deficiency.
• Too much zinc, not enough copper – this is not as common but some pastures can contain more than 5 parts zinc for every 3 parts copper and in these situations the zinc blocks the absorption of copper, creating a copper deficiency.
• Too much potassium – Some pasture have extreme levels of potassium (>50 g/kg DM). Horses on some farms are consuming in excess of 1000% of their daily requirement for potassium. While we don’t have published scientific evidence in equines, data in humans, rats and ruminants show that high potassium diets disrupt the absorption and metabolism of magnesium and calcium, two of the most important minerals involved in bone development. Circumstantial evidence suggests this is also the case for horses.

These problems with pasture are especially evident in a good season when horses are eating diets that are almost solely pasture. Talk to your feed supplier or equine nutritionist about testing your pasture so that they can then tailor a feeding program based around your pasture analysis results.

Beware of the sub-tropical grasses

Sub-tropical pastures that are common found in coastal and hinterland areas including kikuyu and buffel grass come with their own unique problem ... they bind calcium with a compound called oxalate in such a way that it is not available for absorption by the horse. Horses grazing on these pastures become calcium deficient and are at risk of a disease known as nutritional secondary hyperparathyroidism, commonly called Bighead. In ‘normal’ seasons when horses graze these pastures in conjunction with hard feed and hay the amount of pasture and oxalate consumed is too small to cause problems. However, when pasture quality is high and horses are eating a diet that is almost exclusively pasture, a calcium deficiency can occur in some horses very quickly even if a balancer pellet is provided.

Horses grazing these pastures MUST be supplied with enough calcium to keep the calcium to oxalate ratio of the diet above 0.5 parts calcium to 1 part oxalate. To achieve this, use a balancer pellet that has been designed specifically for horses grazing high oxalate pasture or have your nutritionist design a ration with extra calcium.

Pasture... use it wisely

Pasture is a brilliant resource but it needs to be used wisely. Pasture is able to meet many of the nutrient needs of mares and young stock, but nearly every pasture will have mineral deficiencies or imbalances that are easiest corrected through the use of a pasture balancer pellet. The real key to feeding correctly when pasture is abundant is to have your pastures tested so that you know exactly what is too high or low in your pastures allowing you to feed accordingly.

Pryde’s EasiFeed Pasture Balancer Pellets

Pryde’s EasiFeed have a range of pasture balancer pellets to help you feed horses according to the season. The Pryde’s 150 Balancer Pellet is a 15% protein pellet that is ideal for mares and growing horses grazing lush pastures. The 150 Balancer pellet is heavily fortified with minerals allowing you to feed just 600 grams per day to meet the mineral needs of pregnant mares, weanlings and yearlings.

The Pryde’s EasiFeed High Calcium Balancer Pellet with 50 g/kg of calcium has been developed specifically for mares, weanlings and yearlings grazing sub-tropical grasses to reduce the risk of calcium deficiency and Bighead disease that can develop on these pastures.

Pryde’s EasiFeed also provide a free pasture analysis service to their clients so that feeding programs can be tailored to your specific pasture.

For detailed assistance with your mare and growing horses diets and a pasture analysis service, please contact Pryde’s Pty Ltd on 1300 732 267, email info@prydes.com.au or go to Feed Selector