400 Mixes-Part 2
I hope you not only enjoyed Part 1 of this series, but that it gets you thinking about why you do what you do in your loft.
Every living organism uses energy and building materials. These are supplied by food for both animals and people. The pigeon obtains, from the food it eats, the nourishment that supplies energy for work (flying), for producing body heat (winter), for growth during the breeding season, for renewing of the feathers during the moult and other bodily functions such, as the production of crop milk and egg laying.
The fat, carbohydrates and proteins in food provide products that contain large amounts of potential energy. Through the process of digestion these products are changed so that the energy can be used.
It is generally known that 1 gm. of starch contains 4.1 Kcal. Fat when burned by the body provides 9.3 Kcal per gram of energy. It provides twice the energy of starch. The burning of fat and starch, produce few harmful by-products, only water and carbon dioxide. Protein is used for energy only in times of need. It mainly provides the amino acids that are the building blocks out of which the body rebuilds its various parts. As an energy supply it provides 4.3 Kcal per gram, but, the burning of protein for energy uses more oxygen, produces more heat and produces the most harmful waste by-products.
These numbers are not exact, but, averages of the total digestible carbohydrates, proteins and fats provided in a normal diet. Naturally, what interests us most as pigeon flyers is how much energy does a bird need during the various seasons.
Through experimentation it was learned that the weight loss of a pigeon was the highest during the first ten minutes of flight. After forty to sixty minutes of flight the weight loss gradually lowered to a fixed amount. In the following hours of flight, the weight loss is almost constant. From this it was concluded that the pigeon, during the first hour of flight used a different source of energy then in the following hours of flight. In the first hour of flight the bird uses mainly its glucose-glycogen reserves. If we calculate the total amount of sugar in the pigeon’s body, we arrive at a maximum of 2% of the body weight or a maximum of 8 gm.
Everything considered, this is a relatively small reserve of energy for the work required of the muscles. The sugar reserves as an energy provider is not enough for the bird to fly even a short race. For example, a flight of 75 km requires more energy than the 8 gr. of sugar can provide. It is important to realize that the pigeon can only work for about one hour on its glucose-glycogen reserves and that after 10 min. of flight gradually begins to change over to a combination of sugar and fats. After one hour of work the bird uses almost only fat as its energy source. Therefore, on long flights pigeons use their fat reserves as their main energy source.
That the weight loss is double in the first hour of flight can be explained by the fact that one gram of carbohydrate(sugar) contains 4.1 Kcal., and one gram of fat contains 9.3 kcal. In other words, a sprint pigeon runs on its sugar motor and a long distance bird runs on its fat motor. The middle distance pigeon runs somewhere in between.
FAT AS RESERVES
Fat in the pigeon takes different forms. The fat in the blood supply is readily available to the muscles as an energy supply. We find fat deposits under the skin, around the intestines and other internal organs, and in the muscles themselves. Without destroying the form and balance, the body weight of a long distance bird should consist of not more than 10% fat. It we go past this maximum then the extra fat becomes a hindrance to the bird. The feed has to be balanced.
It cannot contain so much fat that to get enough protein and carbohydrates the pigeon consumes to much fat. If too much carbohydrate is digested the body changes it to fat. This also has to be considered when we feed our birds.
Optimum amounts of different foods a pigeon has to ingest daily are difficult to determine. Of all the known avian species the muscle of the pigeon has the highest fat content. For several reasons fat is the ideal energy source for our long distance pigeons. Fat has twice the energy of carbohydrate or protein and the burning of fat does not produce harmful by-products. The burning of one gram of fat produces one gram of water. This water can be used by the bird for other bodily functions and is thus a very helpful by-product. When sugar (carbohydrate) is burned there are also no harmful by-products produced, but, the water is only one half of that produced by the burning of fat.
Pigeons at rest with one half hour of exercise, in the summer months needs about 70 Kcal. of energy per day. The amount of grain necessary to supply this amount of energy is about 23 grams (1 ounce). During the racing season we can estimate 100 Kcal. at the beginning of the week supplied by about 33 grams of grain. To build up reserves we have to supply a maximum of 124 Kcal per day at the end of the week to prepare the birds for the race. In the winter to produce enough body heat, the birds’ furnace needs sufficient fuel. The energy needs increase as the temperatures drop.
Research has pointed out that energy use per hour of flying has a close relationship to the speed of flight. According to Rothe a pigeon uses about 26Kcal per hour of flight at 50 km. per hour, 39 Kcal per hour at 60 km. per hour and at 70 km. per hour uses circa 61 Kcal. per hour. To be clear race results show groundspeed (speed in relationship to the surface of the earth).
This is different than the flight speed (the speed in relationship to the surrounding air). The formula for groundspeed is, the sum of flight speed and wind speed (tail wind = plus and headwind = minus) Alerstam tries to make this theory simpler. He proposes that a bird to use its energy most efficiently chooses a flight speed according to the wind. If we suppose for example that the basic speed with no wind is 70 km. per hour, then, with a head wind it increases its flight speed to 90 km. per hour and correspondingly lowers its flight speed to 55 km. per hour with tailwind. With this we can see that with a wind of 30 km. per hour the groundspeed with head wind would be 90- 30= 60 and with tailwind would be 55 + 30= 85 km. per hour.
The results of the research are not yet perfectly clear, therefore, for the time being we estimate the energy use of a pigeon with prevailing winds at between 30 and 60 Kcal. per hour of flight. The lower amount being for the high groundspeed with tailwind. These observations show the enormous differences in the energy use of our birds during the races.
From the above we can see that our birds burn 8 grams of sugar during the first hour of flight and 3 to 6 grams of fat in the following hours of flight. For the fancier the question is whether or not the pigeon has enough reserves for the expected conditions of the upcoming contest and if the bird has replaced the reserves used in past races to the maximum.
It has been shown experimentally that pigeons on long distance flights show better results with more fat in their rations. Fanciers who prepare their charge by topping them up with extra corn, peanuts and seeds, are in fact on the right track.
To be continued
This article has been reprinted with permission of the “Neerlands Postduiven Orgaan” now defucnt.
The original was written by “A. Coolen” in Nederlands.
Translated by “Nick Oud”
400 Mixes-Part 1 click here.