In this feature, we invite experts to answer your burning questions – please email us at firstname.lastname@example.org if you have an equine nutrition enquiry. (Your questions may be shortened to fit the available space.) This month, Dr Tom Shurlock of British Horse Feeds shares his expertise.
Q. What are the best energy sources for endurance horses? It has been 20 years since I took part and I expect that best practice may have changed?
From Dana Southern, Ashford, Kent
A. The endurance horse needs the sustainability of muscle power, as well as the short, intense bursts. Sustainable power is aerobic; intense power is anaerobic.
Although glucose (generally derived from starch) is needed for the first part of glucose metabolism, other nutrients such as volatile fatty acids (VFAs), which are the hindgut fermentation products such as amino acids, fats etc, can join the second part of glycolysis, to provide energy. Therefore, for intense short power, dietary starch is required, but for more moderate, sustainable power, protein, fibre and fat can be utilised.
For a normal, healthy horse, the amount of starch that can be effectively absorbed from the small intestine is 3.5-4.0g per kg of body weight. Higher amounts will enter the hindgut and will have the potential to disrupt the fermentation of fibre.
So, how do we maintain power and endurance without adding too much dietary starch? When you rode in endurance rides previously, you may have struggled to find a fibre source that delivered sufficient energy to minimise starch levels. Nowadays however, we have the super-fibres, such as beet pulp and associated feeding products. Giving feeds such as British Horse Feed’s beet pulp product, Speedi-Beet, or Fibre-Beet, which is beet pulp with additional, highly digestible alfalfa and oat fibre, means you can fuel sustained muscle contractions and reduce reliance on starchy feeds, using starchy feeds sparingly to fuel the power muscles only.
Q. Are ‘normal’ leisure horses really prone to ulcers, and how can they be prevented?
From Barbara Stone, Exeter
A. It is believed up to 90% of performance horses experience equine gastric ulcers, and as you state, it is likely that many leisure horses also suffer.
Ulcers are caused by a disruption of stomach physiology. The horse’s stomach constantly produces hydrochloric acid (HCl), an aggressive acid prevented from burning the stomach wall by a thick layer of mucus. Stomach acid provides an environment for the pre-digestion of nutrients, as well as stimulating enzyme-release by the pancreas, and small intestine.
Recent research shows that fermentation of some feed products by the gut’s gastric microflora can have a role in ulcer production. The correct pH balance of the stomach encourages growth of microbials that ferment nutrients and help breakdown protein and starch; one of the major end-products released when this occurs is lactic acid, which can generate ulcers in the stomach and small intestine.
(Interestingly however, horses on permanent pasture have a much lower incidence of gastric ulcers. Chewing and producing saliva, which contains neutralising sodium bicarbonate, binds up some of the acid, and suppresses acid-producing bacteria.)
Abnormal behavioural activity (such as stabling and transportation), and a lack of a consistent, high fibre diet, can disrupt the production of mucus lining the stomach, increasing ulceration risk. Ulcer preventions include avoiding obvious stresses, providing plenty of water and moist feeds, and minimising starchy feeds. Ensure any starch feeds are micronized, as the starch content will be gelatinised and more easily absorbed.
In addition, consider introducing beet pulp, as it is high in moisture levels and also pectins, and has a good acid binding capacity; it works well a replacement for starchy feeds.
Consider introducing feeds such as British Horse Feeds’ Fibre-Beet, Alfalfa Blend and Alfalfa Plus Oil; ideal sources of digestible fibre, and natural acid buffers.