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Thread: Antinutrients - A Koi Food Discussion

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    Will's Avatar
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    Antinutrients - A Koi Food Discussion

    I've been looking at a lot of koi food labels and ingredient lists. One common thread I've found is that nearly any high protein (40% or more) food, and many lower protein foods use plant proteins to supplement what their Guaranteed Analysis looks like. Using enough fish meal to get 40% protein is not a very cheap way to do it.

    Manufacturers still want to list fish meal as the top ingredient, so they break down the plant sourced protein into several different listings, so that it still appears that fish meal is the highest percentage ingredient, even though vegetable protein is the main protein source used in the food.

    Some makers won't even specify the source, but mention "plant protein products", leading one to wonder if they even know what goes in, or if it varies. But most products do specify soy meal or soy protein.

    In my reading, I've found that soy, once thought to be a wonder food, is no longer seen as such a good thing for people. Is this where the soy is going, to our pets now?

    Turns out that, on doing a bit of research, there are several "anti-nutrient" factors in soy, and with fish who have no stomach (koi and goldfish - carp in general), these anti-nutrients play a bigger part in the proper digestion of food than it does in people, even other fish. If you start looking online for fish nutrient profiles, most of what you'll find is other fish, fish with a very different physiology than our koi and goldfish have. So, these food manufacturers might not be wholly to blame for being wrong to begin with. Just guilty of incomplete research, not pulling the wool over the eyes of the koi community for better profits.

    Since I mentioned soy, let's pick that ingredient apart. Yes, it does contain a high percentage of the macronutrient protein. But what else is in there?

    Today, we're going to talk about phytic acid. Phytic acid binds with heavy metals and minerals, to include iron, calcium, phosphorus, and magnesium, Many beans, seeds, and legumes are a source of phytic acid, and soy is particularly rich in phytic acid.

    To release the phosphorus that makes up phytic acid, and release the nutrients bound by phytic acid, requires an enzyme known as phytase. Unfortunately, phytase cannot be produced by carp, koi, or goldfish. This means that the nutrients bound by phytic acid are not able to be released by koi or goldfish digestive systems, and pass through their bodies, essentially undisturbed nutrients in fish waste.

    The bad news doesn't stop there. These nutrients are then subject to a slow microbial breakdown after excretion, eventually releasing these nutrients as pollution to a water system. Particularly phosphorus, as increase in phosphates is very encouraging to an algae bloom. Sounds better and better, doesn't it?

    Kind of makes one wonder why they would even admit to using soy, doesn't it? I guess that they are capitalizing on the fish food buyer's ignorance, capitalizing on our ignorance, all the while telling us how awesome their food is. Kind of makes you say "Hmmm", doesn't it?

    Phytic acid is not the only anti-nutient in soy, but it is the first one to really question. Isn't it bad enough? How long will we let our suppliers get away with this?
    Last edited by Will; 11-27-2011 at 04:18 AM.

    Will Schultze

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    ricshaw's Avatar
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    Quote Originally Posted by hewhoisatpeace View Post
    I've been looking at a lot of koi food labels and ingredient lists. One common thread I've found is that nearly any high protein (40% or more) food, and many lower protein foods use plant proteins to supplement what their Guaranteed Analysis looks like. Using enough fish meal to get 40% protein is not a very cheap way to do it.

    Manufacturers still want to list fish meal as the top ingredient, so they break down the plant sourced protein into several different listings, so that it still appears that fish meal is the highest percentage ingredient, even though vegetable protein is the main protein source used in the food.

    Some makers won't even specify the source, but mention "plant protein products", leading one to wonder if they even know what goes in, or if it varies. But most products do specify soy meal or soy protein.

    In my reading, I've found that soy, once thought to be a wonder food, is no longer seen as such a good thing for people. Is this where the soy is going, to our pets now?

    Turns out that, on doing a bit of research, there are several "anti-nutrient" factors in soy, and with fish who have no stomach (koi and goldfish - carp in general), these anti-nutrients play a bigger part in the proper digestion of food than it does in people, even other fish. If you start looking online for fish nutrient profiles, most of what you'll find is other fish, fish with a very different physiology than our koi and goldfish have. So, these food manufacturers might not be wholly to blame for being wrong to begin with. Just guilty of incomplete research, not pulling the wool over the eyes of the koi community for better profits.

    Since I mentioned soy, let's pick that ingredient apart. Yes, it does contain a high percentage of the macronutrient protein. But what else is in there?

    Today, we're going to talk about phytic acid. Phytic acid binds with heavy metals and minerals, to include iron, calcium, phosphorus, and magnesium, Many beans, seeds, and legumes are a source of phytic acid, and soy is particularly rich in phytic acid.

    To release the phosphorus that makes up phytic acid, and release the nutrients bound by phytic acid, requires an enzyme known as phytase. Unfortunately, phytase cannot be produced by carp, koi, or goldfish. This means that the nutrients bound by phytic acid are not able to be released by koi or goldfish digestive systems, and pass through their bodies, essentially undisturbed nutrients in fish waste.

    The bad news doesn't stop there. These nutrients are then subject to a slow microbial breakdown after excretion, eventually releasing these nutrients as pollution to a water system. Particularly phosphorus, as increase in phosphates is very encouraging to an algae bloom. Sounds better and better, doesn't it?

    Kind of makes one wonder why they would even admit to using soy, doesn't it? I guess that they are capitalizing on the fish food buyer's ignorance, capitalizing on our ignorance, all the while telling us how awesome their food is. Kind of makes you say "Hmmm", doesn't it?

    Phytic acid is not the only anti-nutient in soy, but it is the first one to really question. Isn't it bad enough? How long will we let our suppliers get away with this?
    What is wrong with plant proteins and soy for Koi?

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    Kntry's Avatar
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    My take on the fish ingredient is that they don't need it. Koi do not eat fish, not even in the wild. They eat crustaceans, worms, bugs and PLANTS.

    Keep teaching us Will!
    The will of God will not take you where the GRACE of God cannot keep you.

    Sandy, K.O.I., KHA

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    MCAsan's Avatar
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    Actually koi do eat koi.

    In a school of fry you can watch "tobies" knock back smaller fry. Of course the solution to tobyies is to make them food for el gato. I doubt any would make good show fish.

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    Well, they do eat them when they're young but not as adults. :)
    The will of God will not take you where the GRACE of God cannot keep you.

    Sandy, K.O.I., KHA

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    Will's Avatar
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    Quote Originally Posted by ricshaw View Post
    What is wrong with plant proteins and soy for Koi?
    Didn't I begin to explain that, with the discussion of phytic acid contained in soy? Phytic acid is what is known as an anti-nutrient, meaning that it blocks absorption of other nutrients. Many of the nutrients in koi food become unusable to koi or goldfish, because they are bound molecularly to phytic acid through covalent (read, very hard to break) bonds. Although phytic acid will show in analysis to be phosphorus, it is not a bio available form of phosphorus, and actually keeps the fish from being able to absorb other nutrients.

    Plant proteins contained in algae can be easily assimilated by koi or goldfish. Plant proteins in grains and nuts, beans and seeds are easily assimilated by ruminant animals. Ruminant animals are land based animals with multiple stomachs, who chew cud in the transition from one stomach to another. These types of animals produce the enzyme phytase, which breaks the bonds that are tied to phytic acid. Koi and goldfish, with no stomach at all, cannot produce the enzyme phytase, and therefor cannot release the nutrients from the phytic acid bond.

    Will Schultze

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    Appliance Guy's Avatar
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    Nice thread. Gets my brain thinking about nutrition. You bring up some interesting points. I agree, Will, that the foods produced need the ingredients looked at. Wish I could participate in this thread, but I am ignorant of the ingrediaents, the fishes needs and the whole process. Maybe we can get a step by step from a manufacturer so we all have a clear picture of what's going on. For me, I'm just a donkey following the pack.

    I had an employee that was hardcore into breeding and raising various clownfish and gobies. He was working on his masters in Marine Biology (he now is an authority on breeding jellyfish! He's awesome!) and this was one of his projects. He studied food and it's nutritional values. Here in Florida we have the freshest seafood, so he decided to experiment. He rounded up various fresh ingredients and started his own food regimine. What he discovered was the ingredient costs were prohibitive to small scale aquaculture. The foods were superior to packaged foods, but not by enough to warrant the extra expense. So he dumped in favor of purchased foods. Now, the clownfish require different nutrients at different levels of development. Without the proper nutrients, the fish were deformed. Mostly to the effect of having a hump head. So the fish have different food requirments at various stages of development.

    I tell you this because I do believe Koi are similar. I just can't see how one food fits all. Especially because the pond conditions vary extensively. Certainly a 4" tosai Showa in Michigan during winter would have a different nutritional need than a 30" Ogon in Miami during the summer.

    Makes sense to me Will! Now, discovering the nutritional needs is another story.
    Enjoying the ponds....

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    Will's Avatar
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    With no phytase, the nutrients are "tied up", still there for analysis, but completely unavailable to the carp species, which includes both koi and goldfish. The only hope for release of these nutrients is by microbial action, and with no stomach to hold the food, carp don't retain the food long enough for microbial action to occur. In fact, to make this microbial production of phytase even less likely to work rapidly, phytase will not work effectively at a basic pH. Phytase acts at full effectiveness at a pH of 5.5. How many of our ponds have an acid pH?

    Those undigested nutrients pass through the fish digestive tract untouched, and are passed as "poop". At this point, the microbial production of phytase begins to very slowly release these nutrients, since phytase works with very retarded effectiveness at typical pond pH. What does this mean for our ponds? A nice, slow, steady release of pollution, compounding the more we feed our fish.

    Phosphorus is the pollution we can see, as it manifests in increased algal blooms.

    Will Schultze

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    Will's Avatar
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    Quote Originally Posted by Kntry View Post
    My take on the fish ingredient is that they don't need it. Koi do not eat fish, not even in the wild. They eat crustaceans, worms, bugs and PLANTS.

    Keep teaching us Will!
    Fish meal is one of the few ways to ensure a complete nutritional profile for fish needs in a manufactured food form. Fish meal, although the among the more expensive ingredients to base manufactured food on, is cheaper than basing the food on an assortment of tiny freshwater crustaceans and gastopods (worms).

    The plants that fish eat are not rich in phytic acid, for one thing. This link will tell you a bit about the lack of phytic acid in algae: http://www.algaeindustrymagazine.com...th-challenges/

    This link will also help me to move on to another point that old-school koi folks will probably argue with. I'll leave that, though, for another post.

    Will Schultze

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    keep in mind when it comes to fishmeal that is a general term used for the catch of the day. There are specific kinds of fishmeal ie Whitefish Meal, Sardines, Anchovy, herring etc which actually give you a better understanding of what your getting.
    Omega 3's and 6's are readily available in certain fish types in higher levels than others. Nice to see someone else beating this drum because I felt ignored over the previous years that I did. the drum beater before me was South African chris neeves, who did lots of reasearch and ended up manufacturing his own koi food. I find Matt Skylar from kenzen a modern day spokesman for the importance of knowing koi nutrition. Tho it's been said before "keep teaching us Will "...:)

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