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I thought this was an interesting read hopefully you will too part 2: The digestive system and dietary requirements Hi All This post has taken me a while to get on top of, as there is a vast amount of information on carp nutriention some more helpful than others. In this post I will break it down so that I look at the carps digestive system first and how it is effected by temperature and then will go in to more detail about the types of nutrients that Carp need and why. Carp and temperature Carp are cold blooded fish and hence draw their heat from the water around them, hence when the water is hotter ie in the summer the fish will be more active and vice versa in the winter. The carps metabolims just like the carps activity is controlled via the water temperature. A carps digestion iss controlled by enzymes and enzymes have a set temperature that they work best at, if the fishes body temperature is not at the correct level the fish will not be able to metabolise the food as well and hence it will eat less. So in the later part of summer from August through until November the carp are active eating as much as they can ready for winter. This means there digestive system has to be able to handle the large amounts of food they eat. Summers like what we have had this year for carp could prove difficult as the water temperature will reflect the air temperature. This could mean that the period between now and winter for potentail affective carp feeding could be reduced as we have had some very unsummer like weather Carp digestive system In this section I plan to go in to some detail about the structure of the carps digestive system. But before this I want to clear up a couple of technical terms. The first one is chemical digestion and the second is physical digestion. Chemical digestion is digestion that is undertake by enzymes, the enzymes interact with the food and break it down into small fragments. The other is Physical digestion this is the process of physical movement of the fish ie chewing to break down the food it has eaten in to small pieces. Once a carp has located a food item and it feels is safe to eat it it obtains it by using the mouth and the buccal cavity here it is broken down in to small pieces by phyiscal digestion using its pharyngeal teeth and grind ing the food against leather like pads. The purpose of this is to break the food down small enough ready to enter the gut. Any food that is not need to move forward in to the gut is ejected via the operculae (the gills) Here we can see the pharyngeal teeth of a grass carp. These are used to break down the food ready for chemical digestion. The next step in the digestion process is to transport the food from the buccal cavity to the start of the intestine. This is done by passing the ground food along the eosophagus to the start of the intestine and the receptive sack. Carp unlike other fish do not have a stomach and because of this they do not break down there food with acid.Carp have instead an intestine that is twice the lenght of the fish. This will allow for digestion and absorption of the nutrients that the carp requires. As the food moves throught the fish it is broken down in to water soluble parts. This is done by the use of enzymes. Carp have to break down large insolubale molecules such as carbohydrates, protein, lipids and fats so that they can be used by the carp for its growth and maintainance. Below is an explanation of what enzymes are. This picture shows the lenght of the carp gut. The lenght of the gut makes up for not having a stomach and allows for extra absorption of nutrients Enzymes for carp Enzymes are defined as biological catalysts - catalysts are substances that increase the rate of chemical reactions without being used up. So what does that mean? Well for carp to digest its food it uses these enzymes to help break the food down in to useful products so that it can be used to fuel the carp for movement, growth etc. Another way of thinking about Enzymes is that they are like a glove you wear when it gets cold. The glove itself does not change but it speeds up the rate at which your hands warm up as it traps the warmth given off by your body. Enzymes speed up the breakdown of food but are not altered themselves. Carp have 100s of different types of enzymes in there bodies, all having a variety of different roles and functions. The ones I will be concentrate on are relating only to digestion. The one listed below are the most comon ones used and will give you an idea of the An example of some of the enzymes responsible for the digestion in carp are as follows. To digest Carbohydrates (sugars) Carbohydrases enzymes are needed an example of those are Amylases Here is an example of what happens the enzyme break the long sugar molecule up into smaller parts that are easily absorbed. To digest Proteins a group of enzymes called is required. An example of these are Chymotrypsin and Trypsin. Protein is broken down in to amino acids which are used for growth and repair in carp. The amino acids are also easily absorbed. There are many more examples of carp enzymes that can be added but the above give you an idea of how they work. Often in baits now adays enzymes are added to the bait. This helps the carp to digest the food and hence encourages the carp to feed. This in tern should allow you to have a greater catch rate. Absorption of nutrients Once the carp has digested and its food it is absorded into the circulatory system. Like in all animals the circulatory and the digestive systems are linked. Without the interactions of both these systems the carp would not be able to survive as it would not be able to maintain its body functions. The food that it has digested and broken down in to water soluble bits could not be transported around the body if the two systems where not related. I have delibertly simplified the carps digestive system because it would not aid this post to go in to much detail. The next question that should be asked is how can this information help us in the quest to catch carp? Well as we have already seen a carps metabolism is controlled by temperature. In the summer when the water temperature is higher digestion would be more efffective, there for more complex nutrients such as complex carbohydrates, proteins, fats and lipids are more easily digested so it makes sense to feed these in the summer months. These foods also promote growth, just like us the more protein or arbohydrate we eat the bigger we get. The same for carp in the summer they are trying to put on as much as weight as possible to get ready for the winter so they will target foods that will allow them to do this. In winter the carps digestive system will slow down as the water temperature decreases and the ability of the enzymes to funtion at their optimun is decreased. Hence high protein or carbohydrate based bait would not be the best to target a carp with as they may not take the bait due to the effort it would take to digest the food. It would take more energy to digest the food than the carp would recieve from it and hence it would be unfavourable for the carp to do this. Nutrient requirements We have looked at how a carp breaks down it food and what enzymes are involved it is now time to look at what each nutrient does and why it is important to the fish. By having a good understanding of these it will help us to bait more wisely. There is little point in baiting up with a bait that would be great for summer but is next to useless in the winter and vice versa. Below I shall look at each nutrient explain a little about it and why a carp needs it and how this should be related to your fishing. Carbohydrates Carp like any another animal uses carbohydrates as an energy source for daily activity and like us they will store them as fats if they have to many. Unlike us and because carp do not have a stomach they are not able to break down complex carobohydrates (ones with lots of bonds) or in cold weather as there ability to digest food is reduced to reduced activity of enzyme action. There for in winter it would be advisable to use carbohydrates that are not complex and sweet, this may get you an extra bite as the carp would be more likely to take them as they would be easier to digest. Protiens/amino acids Carp need amino acids and protiens for growth and repair. Amino acids are used to construct DNA and Protiens. The ten types of amino acids that are needed for good growth in carp are arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine. Therefore if you are making your own bait and are wondering what type of amino acids would be the best then any of the above would be a good place to start. Remember carp are omnivours and will get a supply of amino acids form there environment. Trail and error will help you to discover the ones they are missing or needing. Also as mentioned above high protein feeds in winter would not be a great idea as it takes to much energy for the carp to break them down. The key to winter baits are high energy but easy to break down and digest. Vitamins Below is a table showing some of the common deficiniencies that can occur if carp do not have enough vitamins within there diet. This chart gives you a good guide about the things you should be aware of when looking at fish carp. It also gives you an idea about the role of individual vitamins and what you could add to your home made boilies. However what I would say here is that Vitamins only need to ne added in very small amounts. If you are not 100% confident with what you are doing do not do it. Buy a good base mix as these will contain the correct vitamins at the correct concentrations. Vitamin Carp Cyprinus carpio (mg/kg diet) Major vitamin deficiency signs in carps Thiamin 2–3 Fin congestion, nervousness, fading of body colour. Riboflavin 7.0 Skin and fin hemorrhages, mortality. Pyridoxine 5–6 Nervous disorders Pantothenic acid 30–50 Poor growth, anemia, skin hemorrhages, exophthalmia. Nicotinic acid 28 Skin hemorrhages, mortality Biotin 1 Poor growth Folic acid N None detected Vitamin B12 N None detected Choline 500–600 Fatty liver Inositol 440 Skin lesions Ascorbic acid 30–50 Scoliosis and lordosis and impaired collagen formation Vitamin A 10,000 IU Faded colour, exophthalmia, warped operculum, fin and skin hemorrhages Vitamin D N Not tested Vitamin E 200–300 Muscular dystrophy, mortality Vitamin K N Not tested Minerals Carp need minerals for a variety of reasons these are for normal bone growth, tissue, blood plasma and hemoglobin formations and also for many enzymatic reactions. As minerals are not easy to obtain in an aquatic enviroment they are a very important to carp. In many boilies these are added to the boilie. Also carp will get there minerals from natural sources such as invertibrates. An important mineral that carp need is Calcium, this they absorb from water and the rest they get from their diet. The point here is that Carp need minerals to function and lead a healthy life. Having a good understanding of the dietary requirements of the fish allows us the tailor our bait to the needs of the fish depending on the time of the year. Fat Carp just like any other animal needs a source of fat as it provides a source of energy and can be used as a fuel store for the winter. In the Autumn you will noticed that carp increase their feeding rates this is because they are building themselves up for winter. As the water temperature drops the carps ability to digest high fat and high protein foods are reduced so they build themselves up before the water temperature drops. However just like us Carp do not need a hugh amount of fat as it will cause damage to the fish and even death. Know your carp diet Knowing what to feed carp with as an angler is a hugh advantage you are able to match your bait to the time of the year you are fishing. A good guide that I use is easily digested food in the winter which is low in fat and protein as it takes longer to digest and the carp are less likely to take it. In summer high fat and protein baits as they are easier to be digested and they carp are more likely to take this type of food type in the winter as it can break down the food and use it effectively. Again like I have said before think abit about our quarry and match your angling and you will be surprised with the effects. I hope some of this helps gives you an understanding of the basics of carp dietary requirements. I have started work on Carp Biology Part 3. This will cover carp behaviour and how they interact with there surrounds including factors like pressure, wind direction and water temperature.