ryelle
Well-Known Member
Bought a nutritional book home from college today so scavanged the rat related bits from it.
British Small Animal Veterinary Association (B.S.A.V.A) - Manual of Companion Animal Nutrition & Feeding.
*by "human foods" it doesn't mean a share of your McDonalds burger, or chips, it means things like left over kitchen scraps - such as cooked potato, sweetcorn, crackers, etc.
British Small Animal Veterinary Association (B.S.A.V.A) - Manual of Companion Animal Nutrition & Feeding.
Because of their widespread use in research, the nutrient requirements of rats and mice are well defined. Nutrient requirements for rats and mice have been published by Clarke et al. (1977) and the NRC (1978).
Food Types:
Rats and mice are omnivores, and will eat virtually anything that is edible. They will even eat other rats and mice if they detect that they are weakened or injured and can be killed.
The main types of commercial diets for rats and mice are pelleted, though some coarse mixes are available. The omnivorous nature of rats and mice means that all human foods as well as the standard feed ingredients may be used to supply nutrients*.
The diet needs sources of energy, such as cereals and cereal products, protein, and of minerals and vitamins. There is some evidence that rats and mice can select from a variety of ingredients to produce a reasonably balanced diet. A sensible approach to feeding wuld be to include elements from each group.
Pelleted Feeds
Pelleted Feeds are cylinders of compressed feed ingredients usually about 9-15mm in diameter for rats, mice and hamsters and 3-4mm for rabbits and guinea pigs.
The use of pelleted feed allows the introduction or ingredients on the basis of their nutritional qualities rather than visual appeal. It also permits easy incorporation of dusty mineral and vitamin premixes with often unpleasent texture and taste. Such minerals and vitamins may also be toxic if ingested in excess and blending them in the feed will ensure even distribution and ingestion in appropriate amounts.
Pelleting usually ensures the intake of a balanced diet since the grinding, blending and compression means that the aniaml is unable to select out favoured ingredients, though identifiable traces of the ingredient can be detected in the pellet. However animals such as the rat may waste much feed it the pellet contains a high level of unpalatable ingredient.
Pellet hardness is very important. A diet that is too hard may prevent the intake of an adequate amount of food and lead to poor growth and often hair loss. The rat is more sensitive to pellet hardness than the mouse. A diet that is too soft may be good for growth but lead to high wastage. A good generalisation is that the pellet should be capable of being snapped between the thumb and first finger without undue force and pain to the digits.
Variation in Dietary Ingredients.
One of the difficult areas in feeding small pets is whether to have variation in the ingredients in the diet or whether to feed a fixed-formula diet. Both approaches have advantasged and a sensible approach needs to be taken.
Advantages of Diet Variation
Novelty: Many owners consider the feeding of their pets with human emotions. Thus just as they with for variety and novelty in their own diet, most owners consider that such factors are important for health contented pets. Even 'treats' with different colours and flavours are now available for small pets.
Stimulation: In restricted conditions, with little other stimulation in the cage, a constantly changing range of dietary ingredients may do much to alleviate bordom, particularly if it involves some foraging activity.
Balanced Diet: A diet composed of a wide range of ingredients taken from the main feed categories, i.e cereals, oilseed, vegetables, fruits etc., is less likely to result in nutritional deficiency than a diet based on a few ingredients of similar type. However it is important that particular flavoured items are restricted in availability to ensure that there is no preferential ingestion of one or a few items at the expense of a balanced diet.
Disadvantages of a Diet Variation.
Gastrointestinal disturbances: Substantial sudden changes in dietary ingredients often lead to gastrointestinal disturbances until the digestive system adjusts to the new pattern of nutrients. Any changes should be phased in over one or two weeks. Where a mixture of ingredients are fed, is it usually possible to change one item from each of the categories each day.
Inappetance: A sudden change of diet in some species, particularly the rabbit, may lead to inappetance, and the animal may starve itself to death rather than eat a new diet.
Overeating and obesity: One of the advantages of diet variation was stated to be novelty. Unfortunately novelty may lead to overeating - the animal eating for pleasure rather than energy. Whilst this may give a contented animal, it will also give a fat, even obese animal, whose life expectancy is severly decreased. With this in mind, the animal given a well designed but bland conventional pelleted diet may be better off in the long term. Certainly is it good practise to avoid giving the animal treats and tit bits.
Assessment of Feedings
Most Probable Nutritional Disorders.
Obesity: Giving rats and mice unrestriced access to highly palatable foods, and feeding food as treats is likely to lead to obesity. Obesity in rodents has been shown to be associated with the development of tumours and reduced life span. The welfare of the animal will be better served by feeding a bland purpose designed pellet.
Further improvements in life expectancy and tumour profile can be achieved by restricting the intake of food to about 60-70% of the typical voluntary intake.
Nephritis: It is common to feed rats and mice excessive amounts of protein, particularly during the maintenance phase. Whilst animals are generally well able to degrade surplus protein, to detoxify the metabolites produced and excrete them, over a period of time this process can lead to kidney damage (referred to as chronic nephritis, nephropathy and several other synonyms). This disease can be recognised as early as 3-6 months of age, progressively developing in severity with increasing proteinuria, and it can lead to death in an old animal.
Feeding diets containing 17-20% for breeding and 13-14% for maintenance will minimise the risk of nephritis. There are additional benefits from feeding a low protein diet, since there are observations that high protein intake, particularly in early adult life, can lead to an increased risk of neoplasms.
Nephrocalcinosis: Innapropriate dietary levels of calcium, phosphorus and magnesium can lead to nephrocalcinosis, a sever renal disease particularly affecting female rats and mice. The disease is very common and a major cause of premature death.
The disease is typified by deposition of crystals of calcium phosphate in the renal pelvis, the peripheral parts of the renal papillae and tubules. Nephrocalcinosis may be observed in animals within a few weeks of life. There is a strain difference in susceptibility of animals to the disease.
Vitamin and mineral deficiencies: Vitamin and mineral deficiencies in rats and mice remain a possibility but are unusual with diets from reputable commercial manufacturers. There are several summaries of symptoms of deficiency, for example NRC (1978) and Rogers (1979).
*by "human foods" it doesn't mean a share of your McDonalds burger, or chips, it means things like left over kitchen scraps - such as cooked potato, sweetcorn, crackers, etc.
