Pigeon Racing and Nutrition of the Muscle

By: Gordon A. Chalmers DVM

As increasing amounts of literature about pigeons become available, it follows that there are many more informed fanciers than ever before. Scientific principles in the nutrition, breeding, racing, and indeed all aspects of the sport are much more evident even though there are many fads and "secrets" that continue to hold sway. In terms of diets for racing. For example, many fanciers are becoming more aware that the flight muscles of pigeons need the cereal grains such as wheat, oats, barley, corn, ect. and not, as many British believed for so many years, the legumes such as peas and beans, as the major fuel: however, the reasons and basis for the feeding of the cereals instead of legumes for racing, may not be so well known or understood. The intent of this article is to discuss the major racing muscles of pigeons, including their anatomy at the gross, microscopic, and submicroscopic (electron microscopic) levels, to try to provide some basic understanding of their function, their fuel supplies, and just what happens in these muscles from the moment of liberation at the race pint, to the end of a long, grueling day, and to draw certain conclusions about these muscles from a nutritional perspective.

By way of introduction I should say that I am not a nutritionist, but a veterinarian engaged in laboratory diagnostic work, specifically in the area of pathology, the science of diseased tissues. I also happen to be a long-time racing pigeon fancier flying in a small club in western Canada, with modest success. For several reasons, I was involved at one time in the study of the muscles of wild animals that were captured through drives or baited traps. Naturally enough, I had to review information on normal muscles and to study the effects on these muscles from physical over-exertion. On e spin-of for me was access to a variety of scientific literature on the muscles of racing pigeons and other birds. The opportunity for me, both as a veterinarian and a racing pigeon fancier, to study these muscles in depth was exciting and rewarding, as I had never seen anything written on this subject in pigeon magazines. To this, day I have not seen anything written in pigeon magazines on the microscopic anatomy of pigeon muscle and practically nothing on the nutritional needs of racing muscle, and none of it with much indication of any scientific basis. I hope that the following information will go a long way toward: Shedding some much needed light on the subject. Refuting some of the misinformation and misunderstanding about the nutritional requirements of the racing muscles of pigeons.

At the outset, it may come as a surprise for many fanciers to learn that much of what has been determined about the muscles of birds in general, has been derived from considerable work on muscles of the racing pigeon, and that much of this work was don in Canada at the University of Guelph in Ontario, by Dr. John George and his colleagues and undergraduate students. The results of this extensive amount of work have been published in various national and international scientific journals. I believe that the results of all of this work can be interpreted as I have recorded them here, and that they represent a reasonable explanation of events that occur in the flight muscles of pigeons during a race.

The next item of importance is to realize that there are two major flight muscles of racing pigeons, as indeed there are for any flying birds. The first and more massive of these are the large muscles found on each side of the keel, and are those we feel with our fingertips as we handle the bird. These great muscles make up about 20% of the total weight of the bird. If we kill a bird, place it on its back, head pointing away from us, and we strip the skin off the underlying tissues, we can see these great muscles lying on and attached to either side of the keel. As we look closely, we see that the "grain" of the muscle runs from the keel in an upward and outward direction at an angle of about 45 forming a "V" with the keel. These muscles are known as the major pectorals and are comparable to the muscles that lie under the breast area of humans, although they are obviously much more powerfully developed in birds. As you might expect, the major pectorals are the most powerful flight muscles in pigeons, as they are in other flying birds: their main function is to drive the wing through the downstroke, which propels the bird forward. The other important flight muscles of pigeons are the much smaller and more deeply located deep pectorals, sometimes called the minor pectorals, which lie under the major pectorals right next to the keel. They make up about 3.6% of the total body weight of a racing pigeon, much less than the mighty major pectorals, their major function is to bring the wing through the upstroke. ( Incidentally did you know that in flight, the pigeon inhales during the upstroke and exhales during the downstroke?)

Another important fact to realize is that, in birds, there are two basic types of muscle, based on the color and function of these muscles. The first of these is white muscle such as that seen best in the pale breast muscles of the domestic chicken. The second is red muscle as seen most prominently in the dark breast muscles of birds such as pigeons, ducks and geese, among other flying birds, for example.

Although the muscles of birds contain mixtures of red and white muscle, it is obvious from the examples cited, that the breast muscles of domestic chickens contain a preponderance of white muscle, whereas those of racing pigeons have a preponderance of red muscle. We will try to explain the difference as follows: If we take a small piece o the major pectoral muscle, which lies immediately under the skin of the breast, cut it longitudinally, ie., with the "grain", process it to produce a thin section stained with special dyes, and examine it microscopically, we see that it is composed of many long, cigar shaped units that are actually specialized body cells called fibers. If we cut the same piece of muscle in cross section and look end on at the cigar shaped units, we see that they are more or less round, oval or even somewhat angular, and that they occur in bundles. (As an example, we would have roughly the same situation if we took a number of pencils to form a bundle, wrapped each bundle with an elastic band and then stacked the bundles on top of one another, as well as end to end.)

Obviously, hundreds of thousands of bundles, both stacked and laid end to end, make up the entire muscle we can feel with our fingers. Continuing our end on view of the muscle fibers, we not firstly that the vast majority of individual fibers in a bundle have a narrow diameter. Based on this finding and several other important and related characteristics which we will discuss more fully, these narrow diameter fibers have been designated as red fibers and in fact make up about 94% of the fibers in the breast muscles. Whereas a majority of fibers are of small diameter, there are many fewer fibers in a bundle that have a much larger diameter and are called whit fibers. These fibers make up only about 6% of the fibers in the breast muscles. We also note that, for the most part, these white fibers are located on the edge of each bundle. Once again, if we use the analogy of pencils, but had mixed thick and thin pencils in a bundle, we would see that, in general, most of the thick pencils representing white fibers would be near or actually touching the rubber band, whereas, most of the slim pencils representing red fibers would be located more deeply inside the bundle. Thus, the predominance of red fibers in the breast muscles of the racing pigeon gives that muscle a red appearance on gross inspection. This red color is related to the presence of myoglobin, a pigmented, oxygen carrying compound peculiar to red muscle in many species of birds and animals. By contrast, the predominance of white fibers in the breast muscle of the domestic chicken imparts a very pale and characteristic appearance to that muscle, because white muscle has very little myoglobin. These basic features serve to outline one of the major differences between a bird such as the racing pigeon, or any migratory species which is required to fly for many hours at a stretch, and a sedentary, non flying bird such as the chicken. There are other differences and we will explore them in more depth as we proceed.

In addition to differences in the diameter of these two types of fibers, what other distinguishing and significant features are there? Well, major investigations have shown that, in addition to having a narrow diameter, individual red fibers have an extensive network of blood vessels running and inter connecting over their surfaces. Red fibers also have a high capacity to take up oxygen, because of the presence of myoglobin, for the metabolism (or burning ) of fuel to produce the energy necessary for flight. Of very great importance of the racing pigeon is the fact that these red muscle fibers function (or as we say, they twitch) slowly.

Because these fibers twitch slowly during flight, they also tire out very slowly. It becomes obvious then that red fibers are those that can handle the sustained effort of rapid flight over many miles, whether the distance is a short training toss, a middle distance race or a major long distance event. In some special situations such as launching into the air, to be discussed later, evidence suggests that the red fibers are also capable of very rapid activity. However, their most important single function seems to be associated with the prolonged, sustained muscular effort of distance flying.

On the other hand, we note that the large individual white fibers have relatively few blood vessels running over their surfaces and that they have a very poor capacity to use oxygen, the burning of fuel, the burning of fuel, because they contain very little myoglobin. In contrast to the red fibers, these large white fibers function (twitch) RAPIDLY. As you might expect, because of their capacity to respond quickly, white fibers also tire out very quickly, and for this reason, it is important to understand that they can in no way be relied upon for sustained flight. If they do not function during prolonged muscular effort, what is their major role? Since white fibers twitch rapidly and tire quickly, they seem to be most important and useful during muscular effort that requires very rapid and even explosive bursts of activity. Thus, white fibers are those that likely operate most effectively to help launch a bird into the air and allow it to dodge in the wink of an eye when it encounters predators, power lines and other obstacles. When your youngsters are dipping and diving in a frenzy of activity and are all over the sky in a flash, these functions are probably handled primarily by the white fibers.

Another important function of these fibers is in the production of heat in cold weather through the familiar process of shivering. The trembling wing tips of a in good physical condition are another example of the function of white fibers. Both of these situations are good examples that illustrate the rapidity with which these fibers operate and just what is meant by fast twitch fibers!

Now, if we were to make use of an electron microscope and magnify and photograph many thousands of times, both the red and white fibers, we would see some further striking and highly important differences between the two. In looking firstly at the red fibers, we see that they contain many somewhat oval structures that ten to be present in chains, like beads on a sting, and that these structures are often separated from one another by what, at first glance, appears to be an empty space. The oval structures are known as mitochondria that, for our purposes, can be compared to a series of furnaces. Naturally, every furnace needs fuel and these "biological furnaces" are no exception. When we look closely, we see that the "spaces" between some of the oval "furnaces" are not spaces at all, but are actually droplets of an abundant and obvious source of fuel. It may come as a surprise to many fanciers, but that fuel is, infact, none other than FAT ! Given the historical ( and incorrect) belief of some fanciers that protein is the major fuel for racing, hence, the traditional emphasis by some fanciers on the use of high percentages of peas and beans as fuel feeds in racing rations, at the expense of cereal grains this information may be even more surprising. As we continue to examine the fine structure of the red fibers, we see that they also contain a considerable number of granules that have been identified as glycogen, a complex carbohydrate (or sugar) composed of many smaller units of the sugar glucose, sometimes also called, dextrose.

The importance of fats as the major fuel for racing, or for any prolonged flight, such as that of migrating birds, cannot be over estimated. For example, there is a small songbird known as the blackpoll warbler that nests each year in the Yukon and Alaska. As fall approaches, these tiny birds work their way diagonally south and east across the continent of North America, feeding and building fat reserves as they travel, until they reach the Atlantic provinces of Canada and the New England states in the USA. When fat depots are filled to capacity and the birds are much heavier, they wait for a high pressure cell moving in from the west and accompanied by winds from the north or northwest. When all is ready, the birds launch themselves into the air and head out over the vast Atlantic ocean. Only when they reach landfall three to five days latter, on the northeast corner of South America, do they touch down again, after an incredible non stop journey for such a tiny land based bird weighing less than two thirds of an ounce! Without fat, this amazing journey of over 2,400 miles (3,900 Km.), simply could not take place.

Next month: Part 2

Reprinted with permission from: Dr. Gordon Chalmers, Lethbridge, Alberta, Canada.