All oils and fats contain fatty acids which make up their distinctive structures. They are digested into individual fatty acids by lipase enzymes in the small intestine.
The blood carries fatty acids to the body cells and there they are re-assembled into cell wall lipids (polyunsaturated fats) and also incorporated into a wide variety of body metabolic, hormone and structural compounds.
Fatty acids are the ‘building blocks’ of many tissues as lipid compounds, including natural anti-inflammatory compounds and hormones.
Fats stored in the muscle cells and replenished by the blood can also be used as an aerobic, or oxygen metabolized, source of energy during exercise and by the diaphragm when a greyhound pants to cool after a race.
Fats supply 2.25 times the energy content per gram as compared to sugars and proteins to the contracting muscles. Studies have shown that greyhounds, in contrast to other sprint athletes and despite their running at speeds of up to 70 km/hour, can utilize fats as an energy source during a race.
Aerobic metabolism of fat can help to spare muscle glycogen which is used as the main energy source used in anaerobic metabolism at maximum speed in the sprint to the line.
Types of Fatty Acids
There are over 100 different fatty acids isolated from animals, plants and micro-organisms. For many years, animal and vegetable fats have been used as a source of energy to provide a cheap, low bulk energy boost for greyhounds.
Fats also are widely used to help counteract dehydration as they provide’ metabolic water’ when metabolized as energy in the body. Each 100 grams of fat, whether as vegetable oil or animal fat, such as suet, lard or meat trimming fat, provides 107 grams of water to the blood and tissues when oxidized as an energy source.
Do not use cooked fat, such a dripping, as the fat can be denatured by ‘burning’ at high roasting or barbeque temperatures and risk damage to the greyhound’s liver if fed on a regular basis. Normally, 60-90 grams of lamb kidney suet or lard (pig fat rendered by boiling) is adequate to assist in overcoming dehydration during the hotter summer month, as well as supply energy for panting.
Certain fatty acids, such as Omega-3 and particularly Omega-6 long chain fatty acids, are used to improve the texture of the skin, manage inflammatory skin diseases, assist the immune system and are essential for optimum brain function and normal growth and development. In fact, in human nutrition, over 25 specific functions have been contributed to the role of Omega-3 fatty acids alone in hormone, neurological and other vital protective immune and cardiovascular benefits in the body.
Over the last decade, the role of Omega-3 (also known as n-3) and Omega-6 (also known as n-6) fatty acids, has been investigated in human and animal nutrition because of their distinctive actions and importance of having an optimum ratio between them to ensure a dietary balance. Some of these fatty acids are termed ‘essential’, as they cannot be synthesised in the body and must be provided in the diet. They are referred to as essential fatty acids or EFAs for this reason.
Omega -3 Fatty Acids
Omega-3 fatty acids are involved in natural anti-inflammatory protective functions, hormone synthesis and the immune system.
They cannot be synthesized in the body from fatty acid ‘building blocks’ and must be provided in the diet. A deficiency can develop which will affect a range of metabolic activities required for normal health and athletic performance in a racing greyhound.
The n-3 fatty acids are based on the parent fatty acid of alpha-linolenic acid, which is converted metabolically to the other n-3 fatty acids
They provide compounds classified as ‘eicosanoids’, that provide natural anti-inflammatory protection to the skin, joints, tendons and other connective tissues. The major sources of these ‘essential’ n-3 fatty acids are animal fats, which contain the converted n-3 fatty acids. The highest concentrations of n-3 fatty acids are found in cold water fish oils, such as cod liver oil, salmon and seal oil.
The vegetable sources only provide alpha-linolenic acid in the oil seeds of flax (linseed oil) and canola and soya bean, but once ingested and entering the metabolic system, they are converted to other n-3 EFAs.
Avoid Excessive Omega-3 Fatty Acids
Whilst the Omega-3 fatty acids cannot be synthesized in the body, supplementing with excessive amounts of n-3 compounds, usually by feeding large amounts of cold water fish or fish oils, such as cod liver oil, can be detrimental.
Excess levels in the blood can result in oxidative stress on the animal, possibly decreasing vitamin E levels in the blood. In racing animals, such as horses and possibly greyhounds, excess dietary Omega-3 may increase the risk of blood vessel fatigue when subjected to high pressures when galloping and result in capillary rupture and bleeding in the lungs.
Omega-6 Fatty Acids
Omega-6 fatty acids are based on linoleic acid and this provides the base for other n-6 fatty acids in the body. The major sources of n-6 fatty acids are provided in beef and chicken fat, evening primrose, safflower and sunflower oil.
Although omega-6 fatty acids also provide a source of eicosanoids, they can contribute inflammatory effects to stimulate tissue reaction. In a study in rats, it was observed that nervous function recovered more rapidly after supplementation with n-3 fatty acids as contributors of anti-inflammatory EFAs, as compared to supplementation with n-6 fatty acids, which appeared to decrease this protective action to healing nerve tissue.
Human studies have found that n-6 fatty acids are more important in the diet than their n-3 cousins. Studies illustrate that an excess of n-6 fatty acids can reduce the metabolism of n-3 fatty acids, even when they are not synthesized in the body.
This in turn can lead to a reduction of their important protective and metabolic functions. It is beneficial to have a higher amount of n-6 fatty acids in food to maintain an optimum n-3 to n-6 ratio.
Research in dogs in the mid 1990’s found that when a ratio of 1 part n-3 to between 5 -10 parts of n-6 fatty acids is maintained, the combination provides the most effective synergistic, natural anti-inflammatory effect in the responsive tissues.
Trans-fatty acids or Cis fatty acids
In the discussion above, the description of fatty acids has been focused on natural ‘cis’ fatty acids which occur in natural foods. Chemically, the ‘cis’ fatty acids have hydrogen atoms on the same side of the double bond which makes up the linked chains in the fat.
However, in recent years there has been much concern and discussion in human nutrition about the dangers of ‘trans’ fatty acids. Trans-fatty acids are synthetically manufactured by the hydrogenation of fatty acids.
This is achieved by adding more hydrogen atoms to the fat molecule, with hydrogen atoms being placed on opposite sides of the double bonds. These fatty acids do not occur in nature and are regarded as synthetic fatty acids and in human nutrition, trans-fatty acids make up about 15% of our fat intake.
They are used in margarine and’ synthetic’ cooking oils used in frying foods, especially chicken fast food, because they last longer and do not oxidise to the same extent as compared to natural cis-fatty acids when over-heated.
The trans-fatty acids have been associated with pro-inflammatory actions and may be involved in allergic conditions and increasing the risk of degenerative disease and heart. Luckily, racing greyhounds do not have a regular daily intake of these potentially harmful fatty acids. However, retired aging greyhounds fed on table left-overs may be more likely to consume ‘trans’ fatty acids.
Saturated and Unsaturated Fatty Acids
No discussion of fats would be complete without the explaining the basic meaning of fat saturation, mono-unsaturated and poly-unsaturated fatty acids or PUFAs. All fatty acids have long chains of hydrocarbon molecules, and they can be saturated, with no double bonds joining the carbon atoms, or unsaturated, where which have one or more double bonds in the chain.
Butter fat has the highest content of saturated fat(57%), followed by palm oil(51%) and least of all, canola oil(7%). Olive oil has the highest level of mono-unsaturated fatty acids (76%) and canola at 63%, both of which are preferred for cooking oils because they are not fully saturated and are not subject to oxidation during storage as compared to the poly-unsaturated vegetable oils.
Linseed or flax oil has the highest natural content of the n-3 fatty acid base alpha-linolenic acid, with canola oil the second best of the vegetable oils at 10%. Of the common vegetable oil sources of n-6 fatty acids, safflower oil has the highest content at 77%, sunflower oil at 66% and soya bean and corn oil around 54% and 52% respectively.
Canola has 20% and olive oil only 1% linoleic acid. This means that combinations of flax seed oil or canola oil, mixed with n-6 oils help to achieve the optimum n-3 to n-6 ratio needed by the body to optimize fatty acid metabolism and function.
Additional Vitamin E
And lastly, because polyunsaturated fatty acids are prone to oxidation during storage and particularly in high oxygen environments, such as rapidly the contracting muscle cells of a racing greyhound, where oxygen passes through the muscle walls containing structural lipids or PUFAs at up to 200ml per kilogram of body weight in a 30 second gallop.
Anti-oxidant protection of the cell wall structural fatty acids with vitamin E and selenium is important. When oils or fats, particularly fish oils, are supplemented to boost energy or provide EFAs for metabolic function, then up to at least 10 IU of vitamin E per gram of supplemented oil should be added as anti-oxidant protection. Well formulated balanced fat supplements for greyhounds have added vitamin E at 1000IU per litre and preferably more.
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