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Feeding for Weight Gain, brought to you by HyGain Feeds

June 2018 by Tania Cubitt, PhD, HyGain Feeds, www.hygain.com.au
Dr Tania Cubbitt is a consulting nutritionist for HYGAIN, a leading authority in equine nutrition providing high quality and balanced feeds and supplements to nurture the best qualities in horses.

Some horses do not maintain their bodyweight easily and it can prove a real challenge to keep them at an ideal weight. Ultimately, your horse’s ribs should not be visible, but they should be easily felt if you run your hand along your horse’s side. 

A common complaint from horse owners is their horse hasn’t got enough topline. This is achieved through the horse working in a manner that strengthens the muscles in their back and the correct diet of quality protein, which helps to build muscle. 

Regularly monitoring your horse’s weight with a weight tape or livestock scale will allow you to identify any changes to their weight early, thereby enabling you to make corrective actions quickly. But first, we must understand why the horse is underweight.

What causes weight loss?

Weight loss can be credited to a number of factors, only some of which are feed-related. The first factor that should be checked when assessing causes for weight loss is the condition of the teeth. Proper dental care is essential to a horse because of the nature of their diet. 

Horses evolved eating coarse roughage and plant materials that require thorough grinding by the molars to break down the particle size of the food. 

Poor worming regimes can also cause weight loss, regardless of what and how much you are feeding. Parasites may compete directly for the nutrients inside the digestive tract. They may also cause damage to the intestinal lining, making it difficult to absorb nutrients. Damage to the intestinal lining can diminish the production of enzymes needed to prepare food particles for absorption. 

Stress can also contribute to weight loss. If your horse is a chronic stall walker, weaver or fence runner, they are burning calories needlessly all day long. Simple management changes, such as daily turnout or the addition of a stall buddy, can alleviate these behaviours. High grain, low roughage diets can also cause stress, as a result of gastric ulcers that are painful to the horse and may discourage them from eating. 

Disease or illness can also interfere with weight gain - either by decreasing the horse’s appetite or by directly affecting nutrient absorption within the digestive tract. An example of this would be chronic liver disease due to the decreased ability to handle protein and fat properly. If all these can be eliminated and your horse is still not putting on weight, the next step is to evaluate your horse’s diet.

What should I feed?

Fibre: Of the three major energy sources (fibre, carbohydrates and fat), fibre is the most important. Fibre is the major component of pasture and hay. Some horses can maintain their weight on fibre sources alone. For the poor doer, however, fibre alone will not maintain weight, but there are fibre sources with higher energy content and digestibility than others. When comparing the energy content of lucerne and grass hays, lucerne hay can provide a horse with more energy than grass hay of similar quality. However, low-quality lucerne hay, which has more stem than leaf, is not a rich source of energy. 

When quality pasture or hay is not available, or if the horse does not readily eat hay or have access to pasture, there are alternative fibre sources that can be added to the diet, such as HYGAIN® FIBRESSENTIAL®, the nutritionally enhanced chaff nuggets. The most common are ‘super fibres’, such as beet pulp and legume hulls (soy or lupin hulls). 

HYGAIN MICRBEET® is a beet pulp-based alternative fibre source. The fibre in beet pulp is about 80% digestible (as compared to 50% for average hay). Soy and lupin hulls are the skin of the bean (not the husk or pod) that is knocked off before oil is extracted from the bean. The energy content of legume hulls is close to that of oats. Certain additives, such as yeast, may help with fibre digestion if the horse has a problem with the balance of microbes in the large intestine. Yeast has been researched and found to improve fibre digestibility. Many feeds from the HYGAIN® range contain probiotics - live yeast-based additive that assists with fibre, calcium and phosphorous absorption. Maximising forage quality should be the first dietary adjustment when trying to achieve weight gain.

Carbohydrates: Carbohydrates, specifically sugar and starch, in the form of grains have been the most traditional method of increasing the energy density of the diet. Obtaining energy from sugar and starch is very efficient due to their simple enzymatic processes. While grain is a concentrated source of energy for the horse, there are some complications with feeding large quantities. The small intestine can easily become overloaded with sugar and starch, resulting in an overflow into the large intestine. This can lead to gas colic, colonic ulcers and even laminitis. When trying to get a thin horse to gain weight, it is often tempting to keep increasing the amount of grain being fed. Unfortunately, if too much grain is fed and the delicate microbial population in the large intestine gets disturbed, most horses will lose their appetite and the situation worsens. Care should be taken not to feed any more than 2kg of grain in a single meal. When large amounts of grain are fed, it should be divided equally over three or more meals throughout the day. Make sure the horse is always getting at least 1.5-2% of their bodyweight in the form of fibre, and a good rule of thumb is to try and stick to a roughage to grain ratio of around 70:30.

Fats: Fats and oils are commonly used in horse feeds to increase the calorie content of the feed or to replace the calories supplied by grains. Fat supplementation has many benefits, including providing calories for weight gain, and providing essential fatty acids to improve skin and coat condition. Feeding fat has also been reported to decrease excitability in nervous horses. Both animal fats and vegetable oils have been fed to horses, although the use of vegetable oils, such as soy, rice bran or canola oil, is more prevalent due to superior palatability.

Fat sources, such as HYGAIN® RBO®, rice bran oil or soybean oil contain 2.5- 3 times more energy than grains on an equal weight basis. Increasing the fat level of the diet is the easiest and safest way to increase the energy density of the diet. Higher energy levels can be obtained by feeding a lesser amount of a high-fat concentrate mix, compared to a concentrate mix containing lower-energy grains. Research has indicated adding 5-10% fat to the total diet has maintained the bodyweight of horses with a 21-25% decrease in concentrate intake. HYGAIN® SHOWTORQUE® is a high fat, no cereal grain textured concentrate, ideal for safe weight gain. Adding fat to a horse’s diet permits safe weight gain, while reducing the chance of colic or founder. Digestion of fat also yields less internal body heat, when compared to other diets. Thin horses will gain weight and do so without having to eat as much grain if the diet is fortified with additional fat.

How long will weight gain take?

Gaining weight on your horse will not happen overnight and horse owners should have reasonable expectations as to how long it will take to avoid disappointment. The 2007 National Requirements for Horses suggested it takes 16-20kg of gain to change a horses body condition score by 1 unit (based on a 500kg horse; 1 to 9 scale). Therefore, a horse with a body condition score of 2 would need to gain around 60kg to increase their condition score to a 5. This would take around six months to achieve and would require a very energy-dense feeding protocol. It is safe to assume a horse can gain one condition score per 60 days, when provided with adequate additional dietary energy and no underlying disease is apparent.

Take home message

Whether your horse is underweight, overweight or just right, it’s important to evaluate their condition through advancing age, environmental changes and performance demands regularly. Addressing unwanted fluctuations before they become potential health risks is the key to maintaining optimal bodyweight. After addressing all possible causes for the horse’s weight loss, increasing the amount and quality of fibre the horse is receiving should be the first dietary change made, followed by increasing the energy density of the concentrate portion of the ration.

To find out more about HYGAIN visit: www.hygain.com.au