Syrian hamster foods - what do we know?*

In the ever-evolving world of hamster care knowledge, food and nutrition is a largely up-and-coming topic in #properhamstercare. This is brilliant for all of us, but can also put us at risk of blindly believing certain terms to mean something more than they do, or to misunderstand nutritional values.

*This is a long article; if you'd like to see our list of recommended and not recommended foods and a summary of why, scroll to the end.

So, we're here with a breakdown of what the currently limited research says about Syrian hamster diets specifically. We will be doing this for dwarf, roborovski and Chinese species where possible in the near future. In places, we will refer to several studies referencing other rodents, mammals and humans but will aim to always tie it into a study referencing hamsters.

At the end, we will provide a list of the foods we specifically recommend along with a comparison of some of the foods we don't recommend. This will not include all brands of hamster food.

From The UFAW Handbook on the Care and Management of Laboratory and Other Research Animals (2010), we understand that Syrian hamsters would primarily eat grains, alongside green plant shoots and roots, insects and fruit.

Where does the recommended Guaranteed Analysis (GA) come from, and what does it mean?

Guaranteed Analysis (GA) consists of the basic macronutrient percentages within a food mix. These are crude protein, fats and fibres. The generally recommended GA is based on an adult Syrian hamster (6-18 months old). This consists of:

15-20% protein

5-10% fats

8-12% fibre

Protein requirements explained

According to the 1975 study, Protein Nutrition of the Golden Hamster, a range of 12-16% protein was acknowledged as adequate for adult Syrian hamsters. For younger Syrian hamsters (under 6 months old), it was recognised that the minimum required protein for positive growth was 15%, and a healthy range 15-20%. This study also showed that not all protein types are made equal, with hamsters displaying higher weight gain from soybean meal and low gain from fish protein concentrate. This was the opposite of rats, and goes to show how different a species they really are.

This conclusion was supported in Management, Husbandry and Colony Health (2012), which states that hamsters tend to grow better with soybean meal as a protein source compared with fish and wheat gluten. Soy proteins have even been proved to lower the progression of renal disease in hamsters and similar species.

We can already see how the recommended make-up of hamster food might start to take form, starting with this research into soybean vs other protein sources.

When considering protein needs for older hamsters, it's important to look at all mammals, in which we see a general decline in muscle mass as a result of ageing. In The changing patterns of whole body protein metabolism in ageing humans (1978), it is shown that "rates of whole body and muscle protein breakdown, per unit of body weight, were lower in elderly subjects than younger adults." When we consider this in-line with the study Metabolic effects of voluntary wheel running in young and old Syrian hamsters, it is shown that muscular activity differs vastly between young hamsters given a wheel versus young hamsters not given a wheel, while there was no notable difference between the muscular activity of older hamsters given a wheel and those who weren't.

This leads us to conclude that Syrian hamsters follow the pattern of a reduction in their muscle mass, and therefore slowing down the breakdown of protein in the muscles. It is commonly understood that if protein isn't broken down and absorbed into the body, it can cause increased bloating and gas, and in more extreme cases, it can end up being converted to glucose which renders the point of consuming large percentages of protein virtually useless.

As a result, Syrian hamsters 6-18 months old should receive between 15-20% protein in their diets, with a gentle reduction over time, and Syrian hamsters over the age of 18 months should receive between 12-15% protein in their diets.

We at Happy Hamsters UK believe that far more research is needed, as in the 1982 study, Nutritional effects on the lifespan of Syrian hamsters, it was found that elderly female Syrian hamsters survival improved with an increase in dietary protein, while male Syrian hamsters survived better with a decrease.

Fat requirements explained

All mammals require fats in their diets - especially healthy ones! Without fats, bodies would eat away at themselves, reducing proteins and carbohydrates to nothing. A deficiency of fatty acids has resulted in loss of hair, scaly skin and profuse secretion of ear wax. So, let's consider what fats are in our hamsters' diets and why they're needed.

In Nutrient requirements of laboratory animals: fourth revised edition (1995), it is shown that hamsters can fare well on a diet with a range of 4-20% fats, however diets feeding more than 10-12% fat were more likely to increase the risk of obesity. There was a link between higher early mortality with those fed on higher fat diets. The study concluded that the fat lipid requirement was around 5%.

Furthermore, a 2011 study, n-3 PUFA prevent metabolic disturbances associated with obesity and improved endothelial function in golden Syrian hamsters fed with a high-fat diet, showed that hamsters fed a diet of more than 20% in fats were almost guaranteed to become obese, as it induced obesity in many of the Syrian hamsters given a high fat diet with 21% fats.

It is interesting to note that the hamsters fed the omega-3 polyunsaturated fatty acid high fat diet didn't differ much in weight to those fed 5% fats, but that it lowered their "good" cholesterol. This shows that keeping an adult Syrian hamster's fats at around 5-10% should result in them staying nice and healthy.

In younger hamsters (under 6 months), it is recommended to aim for 5% fats, as in the 1995 book, we see only a 1% mortality rate when the fatty acids remained between 3-5%. Hamsters between 6-18 months should receive 5-10% fats. If a reduction in activity is noticed after 18 months, owners should gently lower the fats given.

Fibre requirements explained

Fibre is an incredibly important factor in all mammals' diets, as without it, animals would struggle to pass faeces.

The UFAW Handbook on the Care and Management of Laboratory and Other Research Animals (2010) talks about how they provided adult animals with 7-8% protein, and increased this to maximum 14% for more mature animals. The reason for the increase is generally considered important as the activity levels in elderly animals lower, which results in an increased risk of obesity.

In A review of the interactions between fibre and the intestinal mucosa, and their consequences on digestive health of young animals (2003), there was evidence of links between dietary fibre and enteric bacterial infections in young animals. It was concluded that moderate levels of dietary fibre in diets for young, non-ruminant animals seem to be beneficial for their gut health.

It is also very important to be aware of the type of fibre we're including in our hamsters' diets. Barley should be given - as without it can raise the animal's cholesterol very unhealthily, but still be given in moderation. With 25% barley in a hamster's diet, this led to a 16.4% reduction in cholesterol, while going over 25% resulted in an increase in their cholesterol. This was studied in Dose response to soluble fibre in barley in lowering blood lipids in hamster (1998).

All studies point to keeping fibres nice and low in hamsters' diets in order to keep them healthy. Fibres should increase gently with age and lower activity levels to avoid weight gain or obesity.

Based on the studies, it is recommended to keep fibres between 8-12%, with young hamsters under 6 months requiring 5-10% fibre, and hamsters over 18 months able to digest up to 15% fibres.

Starch:Oil ratio explained

Because hamsters' diets are largely created using seeds and grains, it is becoming increasingly important to understand the ingredients that make up your hamsters' mix. It's all good and well to have the correct percentages of fats, fibres and proteins but without considering what goes into the food, it becomes obsolete.

So what is oil:starch, what should it be and why?

Starch includes whole grains (sorghum, barley), legumes (mung beans), cereals, rice and grain-based seeds, etc.

Oil includes soybeans, canola, sunflower, linseed, fennel, etc.

Vegetable oils made from seed crops have higher percentages of fats in them, while starches including barley, mung beans and grain-based seeds are lower in fats. Therefore, when a food mix has lots of oily seeds and not enough grains, this is to the detriment of the animal.

While not much research has been done into what the exact ratio should be, the majority of food brands which provide this have a higher portion of starch and a lower portion of oils.

Our recommended food mixes:

Non-recommended food mixes:

So what is it that makes mixes 'nutritionally poor'?

1. Any mix which doesn't explicitly state which ingredients make up their complete food

2. Any mix which uses vague language around their ingredients i.e. 'vegetable derivatives', 'cereals', 'meat products', etc.

3. Any mix which includes 'puffed cereals', pressed or extruded ingredients and any ingredients (including additives and preservatives) which aren't natural food ingredients

4. Any mix which uses any unsuitable food mix within it, or combines multiple mixes together

5. Any mix which claims ingredients to be 'human grade' in the pet industry - please see the legality surrounding this here.