Developing The Topline - Hoofbeats

e n i l p To DEVELOPING THE

By: Dr. J H Stewart

Photo by Michelle Quinn

The back is one of the most important areas of the horse, allowing the horse to support its own weight and to carry a rider.

Working together, the muscles of the back and upper hind leg provide the majority of force when a horse is accelerating, jumping and working uphill.

Especially when performing work and under saddle, these muscle groups have to support weight while providing forward propulsion and collection.

Making sure these muscle groups are fully developed with correct nutrition, training and conditioning helps your horse perform to their genetic potential and reduces risk of injuries.

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When discussing topline, we are really looking at the visual relationship between the horse’s backbone and the muscles that run alongside it. When a horse has a poor topline, it is due to diminished mass of the back muscles. A sunken appearance through the withers and loins with the vertebrae higher than the muscles beside them, means the muscles are underdeveloped.

The back is one of the most important areas of the horse, allowing the horse to support its own weight and to carry a rider. Working together, the muscles of the back and upper hind leg provide the majority of force when a horse is accelerating, jumping and working uphill.

Especially when performing work and under saddle, these muscle groups have to support weight while providing forward propulsion and collection. Making sure these muscle groups are fully developed with correct nutrition, training and conditioning helps your horse perform to

their genetic potential and reduces risk of injuries.

The amazing athletic ability of our horses results from years of genetic selection, careful breeding and the extraordinary plasticity of muscle. The maximum power of a muscle is proportional to its volume or size; larger muscles have more capacity for powerful contraction – and this is why topline is important. These muscles are not just important for the appearance of the horse, they are critical for balance and strength. Risk of injuries is also linked to topline development – when muscles fatigue, the horse begins to load it’s legs asymmetrically.

Age, training type and intensity, nutrition and conformation can all have a significant impact on the properties of muscle fibres (Table 1.). Saddle fit and the rider’s skill are also important. But first and foremost are exercise and nutrition – the diet must support the muscles as they respond and adapt to the workload.

Table 1. Causes of diminished topline

Working together, the three main topline muscles are: 1. The longissimus dorsi, the largest and longest muscle in the body. It extends from the pelvis, across the loins and up to the neck, attaching along the way to the ribs, back, thoracic and neck vertebra (Figure 1). It is the most powerful extender of loins, back and neck. It also flexes the spine laterally, from side-to-side. The longissimus dorsi muscle is extremely important in the horse to maintain posture, allow for extension, and support the rider.

If underdeveloped, the horse will be unable to elevate its back, produce lateral movements of the spine or readily support the added weight of the rider.

Diminished Topline

(Figure 1) The longissimus dorsi

Over-training

2. The latissimus dorsi, the large, flat muscle covering the width of the middle and lower back. Originating from the vertebrae, it extends from the highest point of the withers and attaches to the forearm before inserting on the vertebrae of the thorax. (Figure 2). Its action is to flex the shoulder and to draw the body forward as the forelimb extends.

Conformation (Figure 2) The latissimus dorsi

Poor saddle fit Unbalanced rider Ridden too young Weak abdominal muscles Confinement - not enough free movement

3. The trapezius, the flat triangular muscle that attaches the neck and chest vertebrae to the shoulder blade (scapula) and to the vertebrae behind the withers. Its role is to elevate the shoulder and draw the shoulder blade back and forth.

Incorrect exercise program Weight loss diets (Figure 3) The trapezius

Poor quality nutrition Ageing Multiple foalings

‘Topline’, not to be confused with ‘cover’, is the amount of muscle along the neck, back, loin and croup.

Muscle fatigue Inadequate rest between work sessions

CROUP

LOIN

BACK

WITHERS

Good Topline

Continued

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Nutrition and the diet Diet has a major impact on body composition, i.e. the amount of bone, muscle, and fat and importantly, the powerto-weight ratio. This directly affects power, soundness, balance, strength, and time to fatigue. Muscle is made from amino acids that are part of the feed protein. The amount and type of amino acids in the feed is the main driver of protein synthesis in horses.

Body condition score ‘Cover’ or condition is generally judged using the body condition score (BCS).

Research has shown consistently that body condition score has significant limitations and is not reliable for evaluating fat or body composition in the majority of horses and ponies.

Topline Experience in visual appraisal and learning what to look for are important.

Look over the withers, along the back,

over the hip and for stifle definition. If the muscles are sunken along the withers and back, saddle fitting can be a problem and the lack of muscle can negatively impact attitude and performance. Pain may be felt by the horse and movements that require using the back can be difficult, even though muscling over the hip and hindquarters is adequate. When the entire topline and hip are poorly muscled with a ’pointed’ look and the vertebra higher than the muscles, the croup flat and/or narrow stifles, the horse will lack the strength to perform the exercises we ask of them.

Exercise will condition muscle but work alone won’t build or maintain muscle. The diet must provide nutrients necessary to build new muscle cells and increase the size of existing muscles.

The protein requirement for exercising horses depends purely on the workload the more a horse works the more muscle it can build – provided the diet supports the work.

How to assess protein intake for your horse - percent protein (%).

Quantity: The percent protein of a feed cannot be used as a measure of feed quality. Horses require a specified amount

www.greenvalleynaturals.com.au October/November 2021 - Page 14

of protein - a number of grams of protein each day - not a percent. Comparing feeds on the basis of their % protein is no help at all in determining the body-building power of a feed. If, for example, a feed is 10% protein and a horse eats 3kg of the feed – the horse receives 300g of protein.

If another feed is 20% protein and a horse eats 1.5kg - it still receives 300g of protein.

If you multiply the % by the number of kg fed, then you will know the number of grams of protein you are feeding each day – and whether it meets your horse’s needs.

But it may not be all ‘useable’ to your horse. Not all protein is equal.

Quality: In specifying a dietary protein requirement, we are aiming to meet the amino acid requirements. The quality of the protein in the diet is determined by the number and amount of amino acids in that protein. Every protein in nature is made to a precise and specific recipe of amino acids. And it’s the same for the tissues in the body – each has an exact formula.

Building body tissues can be compared to making a cake. If, for example, you want to make a chocolate cake you need eggs, sugar, flour, cocoa etc. If you run out of cocoa, chocolate cake production stops. You can make a different cake, but the creation of chocolate cakes stops.

Similarly if the body runs out of a single amino acid needed for muscle building, the creation and enlargement of muscle cells stops.

Unusable amino acids are converted to fat. In this way the amino acids in the diet determine the response to training, body composition and the amount of muscle versus the amount of fat. The % protein of a feed is of no significance in determining its suitability for your horse. If it doesn’t provide all the amino acids, it won’t be useable protein – so a 30% protein feed may only be 10% if the amino acids needed by the muscles are not present.

Some feedstuffs have a better amino acid profile than others. Whey, soymeal and lucerne are all excellent sources of the amino acids needed by muscles. Most grass hays, cereal grains and grain byproducts provide poor quality protein and can’t meet the muscle-building needs of growing and/or working horses.

Exercise: The ability of muscle to increase in size, shortening speed, strength and resistance to fatigue allows us to condition horses for the demands of exercise and athletic pursuits. It also means reduced

18kg BLOCKS

Contact us for advice on equine nutrition and equine clinical nutrition Products available around Australia in produce stores through AIRR and at Veterinarians and Vet Clinics through Cenvet & Provet

exercise-induced injuries, better overall health, less stress during physical activity, decreased time to recover and less fatigue after exercise. Correct conditioning changes body composition (i.e, the amount of muscle, fat, bone etc.), as well as the ability to move at various gaits and perform specific for the discipline.

There is much advice and many exercise systems and programs available to increase topline and help transform your horse into a willing and happy ride.

These commonly include hill-work, backing exercises, collection, stretching, lungeing, pole work, gymnastic exercises and dynamic mobilisation routines, transitions, lateral and circle work.

Feeding and exercise – timing makes a difference As well as the composition of the diet, the time of feeding is important to fine-tune performance. Hard training causes muscle damage - hundreds of tiny, microscopic rips and tears occur during intense exercise.

In addition, intense exercise is a catabolic October/November 2021 - Page 15

process involving the breakdown of body stores.

By supplying the correct balance of carbohydrate, specific essential amino acids and anti-oxidants at certain specific times, the catabolic state can be switched to an anabolic (rebuilding of tissue) state, enabling muscles to recover and respond more quickly to training.

To take advantage of the window of opportunity created by increased muscle blood flow and high levels of the hormones used to fuel muscles, providing a small feed of high-quality protein an hour or two before and immediately after work, can transition the horse to an anabolic (bodybuilding) state.

The processes of refuelling and repair also require water and electrolytes. By providing 30grams of salt and free access to water immediately after work and again 2 hours later, along with some sugar/starch (oats or processed grains), helps muscles to repair, build and refuel.

GROWING HORSES Whether foals, weanlings and yearlings develop muscle or lay down fat is determined in the first instance by the quality and quantity of protein in the diet - energy, vitamins and minerals play supporting roles. Correctly fed youngsters achieve greater gains in wither height, reach mature height earlier and deposit less fat because their essential amino acid requirements are met. They also have a reduced risk of developmental bone disorders.

Although weight and height measure growth, they are not sensitive enough to reveal the effects of lowered amino acid absorption on skeletal or muscle development.

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OLDER HORSES As horses age their ability to maintain muscle mass gradually decreases. Muscle loss is caused as much by poor protein and lack of exercise as by increasing age.

Older horses are also susceptible to loss of vertebral column flexibility and increased healing times. Adjustment of the amino acid intake can reverse and delay muscle loss. Although older horses do not require special feeds, they do require the correct quantity and quality of protein. Veterinary clinical conditions, such as tying-up, insulin resistance and Cushings can become chronic with age. They all affect metabolism and loss of muscle tone can result.

Veterinary conditions can affect topline If diet and exercise are appropriate and correctly matched, a veterinary examination becomes important to identify other conditions that contribute to lack of topline (Table 2). Back pain is often due to more than one problem and diagnosis can be difficult if it only causes lameness or poor performance during exercise. Back pain is very complex because it can originate from one or several structures and tissues –- muscles, tendons, ligaments, bones,

Table 2. Veterinary conditions that can affect topline Arthritis Back pain Cushings disease Dental problems Disc degeneration Facet joint osteoarthritis Fractures of vertebrae Immune disorders Kissing spines Ligament issues Muscle soreness Muscle strain Sacro-iliac problems Stomach ulcers Vertebral subluxation

joints and nerves. Of horses with back pain causing asymmetry or loss of topline, up to 17% have multiple, concurrent injuries.

The most common site is the longissimus dorsi. Correct diagnosis is essential for correct treatment and therapy.

Gaining weight just requires an increase in calories – a simple enough principle.

But it is important to know what type of ‘weight’ you wish to increase – muscle, fat or both? To build muscle the amino acid composition of the feed and a proper exercise program are important.

Dr Jennifer Stewart CEO BVSc BSc PhD Dip BEP Equine Veterinarian and Consultant Nutritionist.

Dr Jen Stewart is currently the only practicing equine veterinarian and clinical nutritionist in Australia with more than 40 years experience. Jen has been developing premium formulas for studs, trainers and feed companies - such as Mitavite - in Australia and around the world. Consulting to leading international studs and trainers in various countries while working on research projects and being involved in nutritional management of a variety of equine clinical conditions, including colic, tying-up, laminitis, performance problems, developmental orthopaedic diseases and post-surgery.

Jen’s vision is to provide a world best-practice in equine veterinary nutrition and to BRING SCIENCE TO YOUR FEED BIN.

Dr Jennifer Stewart www.jenquine.com Equine VeterinariansAustralia www.ava.com.au

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