A C Highfield
There is a great deal of misunderstanding concerning the role of
vitamins and minerals. Many people believe that the more you get of
both the better - this is categorically not true, indeed, some
vitamins and minerals can be positively dangerous if taken in excess.
What is actually required is a balanced intake of essential vitamins
and trace-elements - not massive doses of individual vitamins in
isolation which serve only to upset the balance and may cause relative
There are two common ways in which additional vitamins may be given:
Oral vitamin supplements
These are useful as a guarantee that all necessary vitamins are being supplied - but again, they are not essential if the base-line diet is of high quality and is sufficiently varied. Animals on natural browse do not need vitamin supplements, although calcium supplements may still be necessary.
These should only be used to deliver specific vitamins in cases where a specific vitamin deficiency is known to exist. We are totally opposed to the routine use of vitamin injections - in most cases, they serve no useful purpose and indeed are a frequent cause of introduced infection via the injection site. Very few deficiencies are so acute that the much more effective and safer oral delivery route is not a satisfactory mode of treatment. Acute vitamin-A deficiencies may be dealt with by injection, but few other cases require this treatment. The use of a routine "vitamin booster" before or after hibernation is a complete waste of time.
VITAMINS Vs. MINERALS
Many people are unclear as to the difference between vitamins and minerals, and especially about how the two interact (many minerals, calcium for example, depend upon the presence of certain vitamins such as vitamin-D before they can be absorbed).
Vitamins are organic substances which help regulate bodily functions. Acting as co-enzymes, vitamins aid the action of enzymes during the metabolism of dietary nutrients. There are about a dozen major vitamins, a deficiency of any one of which will result in a serious deficiency disease. Vitamins are only required in relatively small quantities, but have a major effect upon the body's reproductive, digestive, nervous and muscular systems. Vitamins also affect tissue growth and anti-body production.
Some important vitamins are:
Important to the condition of the skin and mucous membranes, eye (especially retinal) condition, biochemical and reproductive functions. Plants contain carotene which is converted to true vitamin-A in the body.
The B-complex vitamins are water soluble and excesses are excreted in the urine. Vitamin B1, thiamine, is a regulator in the carbohydrate metabolism; Vitamin B2, riboflavin, is a co-enzyme in energy release and interacts with vitamin B6 and vitamin B12; Vitamin B3, niacin, is also crucial to the energy metabolism and is often obtained by converting the amino-acid tryptophan - this process requires the presence of thiamine, riboflavin and pyridoxine; Vitamin B6, pyridoxine, is involved in energy conversion from glycogen and in the synthesis of haemoglobin and antibodies; Vitamin B12 interacts with folic acid to govern the production of red blood cells. A deficiency causes pernicious anaemia and neurological symptoms. This vitamin is only produced within the gastro-intestinal tract when various micro-organisms act upon trace level cobalt. Deficiencies can occur following malabsorbtion syndrome or as a consequence of severe parasite infestations. The B-complex is just that. A matrix of interacting and inter-dependant compounds.
Sometimes called 'the sunshine vitamin', vitamin-D is a fat soluble vitamin which is essential to the absorption and utilisation of calcium and phosphorous, as such, it plays a major role in bone formation. It can be obtained either naturally, by the action of ultra-violet light on sterols in the skin, or orally by supplementation - virtually all specialist calcium/mineral supplements intended for reptile use contain vitamin D in sufficient quantity.
Vitamin-C has many functions, but as it is present in almost all fruits and green vegetables, deficiencies are extremely unlikely in tortoises.
Many plants contain vitamin-E which is an antioxidant and works in conjunction with vitamins A and C.
A fat-soluble coagulation vitamin. This vitamin is synthesised in the gut by bacterial action and is also found in plant foods. It is especially abundant in green, leafy plants.
Minerals are quite different from vitamins and are both chemical
regulators and construction materials - Calcium forms a major part of
a tortoise's body, more than any other mineral. Calcium deficiency is
also extremely common as a growing tortoise requires substantial
quantities of this mineral in order to build its skeleton.
Phosphorus is the second most abundant mineral in the body. It functions along with calcium. A balance of calcium and phosphorus is needed for these minerals to be effectively used by the body.
Phosphorus plays an important part in almost every chemical reaction
within the body. It is important in the utilization of carbohydrates,
fats and protein for growth, maintenance, and repair of cells and for
the production of energy. It aids in the transference of heredity
traits from parents to offspring. It is also necessary for proper
skeletal growth, kidney function and transference of nerve impulses.
Miscellaneous trace elements
Calcium, chlorine, phosphorus, potassium, magnesium, sodium, and sulfur are present in relatively high amounts in the body tissues. Other minerals are present in the most minute quantities but are essential for proper body functioning. Iron, copper, and fluorine are present in sufficient quantities from deep green leafy plants. Iodine is needed to maintain a positive calcium balance, so a multi-mineral mixture containing iodine should be provided in addition to supplementation of raw calcium.
Try to ensure that all diets are as varied as possible - in this way,
a wide cross-section of trace elements will be made available.
Provide vitamins orally rather than by injection for preference.
The regular use of a safe, properly formulated multi-vitamin and mineral preparation will ensure that dietary deficiencies do not occur.
Aim for a high calcium - low phosphorous
balance in tortoise diets