The problem with muesli mixes
For many years muesli mixes have been popular as rabbit food but the health risks associated with feeding them have been recognised. In 1996 a paper was published that highlighted the problems of selective feeding from this mixtures. More recent research has confirmed that selective feeding is a problem and that obesity and inactivity can be induced by feeding muesli mixes as well as dental disease.
What are muesli mixes?
Muesli mixes are a mixture of cereals, legumes, pellets, extrusions and, in some cases, other ingredients such as locust beans or alfalfa. More about the ingredients can be found here. The mixtures are cheap to produce, easy to store and heavily marketed by the food manufacturers. Cereals are the staple ingredients of these mixes and they are high in starch and low in fibre, so they are fattening, which is acceptable for short-lived rabbits that are reared for meat, but unacceptable for pet rabbits that can live for up to 15 years. Some of the ingredients of muesli mixes are more palatable than others and selecting out favourite ingredients from the mixtures is a big problem. Although the overall nutritional analysis of the mixture may be acceptable, there is considerable variation in the analysis of each ingredient. The manufacturers know this and overcome any deficiency in one ingredient by adding that is rich in the deficient nutrient or they rely on a vitamin and mineral supplement.
The vitamin and mineral supplement comes in powder form, so it is usually incorporated into the compressed grass based pellets, otherwise it would fall to the bottom of the bag of food. The pellets are the least palatable ingredient of muesli mixes so most rabbits do not eat them and they are left in the bottom of their food bowl only to be discarded by the owner, along with the vitamin and mineral supplement they contain. Although it is possible for the vitamin and mineral supplement into a more palatable extruded biscuit, this is more expensive for the food manufacturer as some of vitamins are destroyed in the cooking process, so more supplement is needed, which adds to the cost of production.
Why do muesli mixes lead to dental disease
The ingredients of muesli mixes are not sufficiently tough and fibrous to wear the teeth correctly and to keep the guts working properly. They are also fattening and can lead to vitamin and mineral deficiencies. Laboratory studies have shown that a dietary calcium level of 0.6-1% is required for optimum bone calcification yet most of the ingredients of muesli mixes contain nowhere near this amount. For example, two of the favourite ingredients that rabbits pick out of the mixes are the yellow flakes of maize and the green flakes of peas. Maize contains 0.04% calcium, which is approximately one sixteenth of the amount that is required. Peas have slightly more calcium in them (0.12%) but the rabbit still requires five times this amount so if a rabbit picks out these ingredients, in time, it will develop weak bones and teeth.
Feeding muesli mixes to groups of rabbits
The problem of selective feeding is even worse if rabbits are fed on muesli mixes when they are weaned from their mother at a few weeks of age. At this stage of their life, they need a lot of calcium because they are growing. Litters of rabbits are weaned as a group and some of the babies are more likely to develop problems than others. Offering a mixture of food to a group of animals means that the dominant individuals will eat the most palatable ingredients (i.e. calcium deficient maize and peas) and the subordinate ones will be left with the supplemented pellets. The dominant ones are more likely to go on to develop dental disease.
If young rabbits do not get enough calcium, the bone surrounding the teeth is weakened so that the roots of the teeth press on the nerve supply to the teeth when the baby rabbit tries to eat hard food, such as hay. These rabbits never eat hard food so the owners think their rabbit 'doesn't like hay' even though they give it to them. Most owners know that hay is good for rabbits and will often buy lots of different types of hay or dried grass to tempt their pet. They feel guilty when the rabbit doesn’t eat it, especially when the rabbit goes on to develop dental problems. It is hard for these owners to realise that if their rabbit had not been weaned on to a muesli mix, it would have been able to eat plenty of hay and enjoy all the health benefits that go with it.
What about vitamin D
Vitamin D is a vitamin and a hormone with a range of physiological effects. It can be obtained from the diet or produced within in the body in response to exposure to ultraviolet light. The vitamin D content of plants is also enhanced by exposure to sunlight so dried vegetation, such as sundried hay will contain vitamin D whereas grass does not. In muesli mixes, vitamin D is usually in the supplement that is incorporated in the pellets. The main function of vitamin D is to regulate calcium homeostasis by its effects on the intestine and bone. It increases calcium absorbion from the intestine and stimulates mineralisation of bones and teeth. Rabbits that are exposed to sunshine do not need vitamin D as they manufacture their own. Rabbits that are kept indoors and are fed on muesli mix can be vitamin D deficient if they don’t eat the pellets with the vitamin and mineral supplement. These rabbits will have real problems absorbing sufficient calcium to mineralise the teeth and bones if they pick out the calcium deficient ingredients from the muesli mix.
Why do muesli mixes lead to obesity
Most of the ingredients of muesli mixes are high in carbohydrate and low in fibre. Although some high fibre components, such as grain husks, locust bean pods or alfalfa strands may be added to the mixture to increase the fibre analysis of the mixture as a whole, many rabbits do not eat them. The mixtures contain very little moisture and are a concentrated source of fattening food that a rabbit can eat quickly. If the rabbits is also kept in a hutch or small run, with little opportunity to exercise, it will become obese on a diet of muesli mix. Many health conditions, such as arthritis, sludgy urine and a dirty bottom are linked with obesity. Fat rabbits cannot reach their perineum to eat their caecotrophs, which become entangled in the fur. This is unpleasant for both the owner and the rabbit.
Why are muesli mixes so popular?
Muesli mixes are convenient, palatable and easy to store. They are cheap and widely available. Bags of muesli mix are available from agricultural merchants, pet shops, supermarkets, garages, garden centres, on the Internet and from pet food retailers. Muesli mixes are a favourite with rabbit breeders with large numbers of animals to feed. The breeders may not recognise the dental problems that these diets can cause because their rabbits do not live long enough.
Rabbits are very popular pets so, from the food manufacturers point of view, the market for rabbit food is big and profitable and therefore attractive. Money comes before the health of the rabbit. The market but is also competitive so each brand is heavily marketed. The advertising blurb on the side of the packets of muesli mixes is often inaccurate and misleading. It encourages rabbit owners to believe that their brand of muesli mix is good for rabbits despite the all the veterinary literature to the contrary. Without any evidence to prove their statements, manufacturers use phrases like ‘stimulates a rabbit’s appetite and foraging instincts, with a selection of ingredients ideally suited to keep it healthy and satisfied’ or ‘ it’s special formulation will keep your rabbit fit, inside and out’ to describe their foods. Some companies even suggest that their muesli mixes are ‘good for rabbit’s teeth and bones’. This is not true. The experimental study in which a group of rabbits were only given muesli mix to eat confirmed that, predictably, they developed dental disease and put on weight. This was sad for those rabbits but it did prove a point and the food manufacturers are changing tactics and encouraging rabbit owners to feed nuggets and hay instead. A leading rabbit food manufacturer and a leading pet store have made the decision to abandon muesli mixes. This can only be good news.