| Koi Foods - proteins and carbohydrates
Hi,
I have often wondered where the myths surrounding koi foods originate. There are many very good koi foods on the market. We just have to look at the results koi keepers are achieving.
Think of koi foods as you would a cake mix. Different ingredients are added at certain proportions to get the final mix of the cake. These proportions are calculated around the final product - the 100% cake.
View koi food as a ton (1000 kg) or 1 kg or one pellet - you mix different ingredients to get to your final product. The ingredients are added at certian proportions to get to a final product.
Much research has been done over many years on each individual ingredient. The exact composition of each ingredient is know before hand.
The effect of the manufacturing process on the ingredients is known before hand. The digestability before and after manufacture is known.
Most important is finding out what the creature (in our case our koi) actually needs. Its just not cost effective to have 100% protein in our pellets when the koi can perhaps only digest and absorb 40% protein. The levels of the vitamins and minerals needed have also been researched. So we need a target to begin with.
There is much information available on this aspect of nutrition. For arguments sake lets imagine we need (or want to produce) a koi with say 38% protein.
Before we look at the protein sources we realise that the creature needs energy to perform the metabolic tasks in the body - so we turn to energy sources - carbohydrates (and lipids).
Carbohydrates are essential in koi foods. Studies have found that fish foods with out carbohydrates have retarded growth rates. So carbs are good. Carbs also perform a vital function they act as a digestable binder to deliver the nutrition to the gut of the koi in an aquatic environmnet. A very important task. Carbs also have another very important function - to dilute the protein to levels which are required.
To begin with we add perhaps 25% carbohydrate, after looking at the various carbohydrate sources available.
Now we add a protein source. There are many, but it has bee found that fish meal is a vital source of protein. Studies have found that if fish meal in koi foods is below a certain percentage of the diet then growth is affected.
Many studies have been undertaken to find alternative sources of protein for fish diets.
Fish meal in its raw state is about 60 - 65% protein. It contains many, if not all the nutrients needed in a koi diet. The quality of fish meals do vary but this is known before handand and taken into account.
So to get the protein level down to about 38% we add more carbohydrate and reduce the amount of fish meal. A koi diet with about 38% protein has around 30 - 32% carbohydrate.
We tend to worry about that level of carbohydrate and have been led to believe over the years that around 10% carbohydrate is deseriable. Well the facts are that you will have around 32% carboyhdrate in a 38% protein koi food. But there is more to this aspect -
As you decrease the level of protein in the pellets you have to make up the 100% of the forumlation. So if you reduce the protein to an unhealthy 16% (which some koi foods have) the carbohydrate levels will go up to 68%. Also an unhealthy level. Do you really want to feed your fish 68% carbohydrate?
From a practical point of view there will always be a balancing effect between protein and carbohydrates in koi foods. The more protein the less carbohydrate.
Is it not perhaps better to feed a "high" protein diet but feed less in terms of quantity? The koi will be getting its daily dose of protein and the carbohydrate levels will be kept down.
The metabolic rate is temperature dependant. This we all know. As temperatures decrease the metabolic rates decrease - it does not change. Our koi need less of the same things - the nutrition elements of the pellets i. e. protein, carbohydrates, lipids, vitamins and minerals - the important thing is that the digestion does not change - it simply operates at a lower level.
When we get to about 10C or 50F everything has slowed to the point that our koi have very little appetite as the metabolism is very slow - at a minimum. Their bodies still require the nutrition that was fed to them at higher temperatures - but much, much less of it. They can get by a very little food.
So if you feed the same food you simply reduce the frequence and the amount until they stop feeding naturally. You always get some individual koi that breaks the rules and keeps on feeding when the whole collection is lying freezing on the floor mumbling obsenities at the weather.
In winter Koi do not need more digestable protein - there is no such thing. They need a very little protein. Koi do not need higher carbohydrate sources - they are cold water creatures and carbohydrates are not needed to produce body heat as in mammals. Their enery requirements are minimal. So they need less of everything that we nomally feed them.
Wheatgerm:
Wheat germ in its raw state has about 28 - 30% protein. It is deficient in many of the essential amino acids needed koi. It is therefore impossible to get a pure wheat germ food. We see that most wheat germ koi foods have around 32% protein (am I correct on that one?). To get to this level of protein you will have around 36% carbohydrate, 10 - 15% wheat germ and another protein source. This other protein source would in all probability be fish meal. It could well be other sources of protein such as blood meal, feather meal. Some of the leading brands of wheat germ foods have excellent amino acid profiles which leads me to suspect that there is a high proportion of fish meal.
So there is no such thing as awheat gem koi food - but there are koi food with wheat germ in them.
As for the digetability of wheat germ. Again we look at what koi really need at low tempertures. Very little food, so we do not need more easily digstable anything - they simpy cannot use it.
Wheat germ is a plant source of protein. Plant sources tend to be less digestable than animal source of protein. The only reference I can find about the relevant digestability of wheat germ is that wheat germ is "more digesable than other plant sources of protein". It seems as though it was a short step to modifying this to "wheat germ is more digestable".
Kind regards,
Chris
| 
11-03-2006
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