Gordon A Chalmers, DVM

Note: This material was published originally in the 1992 year book of the Canadian Racing Pigeon Union, and has undergone several modifications and additions since that time.

Fat is the major fuel needed by racing pigeons during the racing season, and indeed, by any species of wild bird that flies extended distances, as in Spring and Fall migrations. It has been noted that the capability of birds for storing triglycerides as an energy reserve, exceeds that of other classes of vertebrates (Blem, 1976). The fatty acids of these triglycerides are predominantly of the 16 and 18-carbon variety, and generally, are more unsaturated than those of mammals.

The facts about fat as the key fuel for racing were established many years ago, and considerable work on this subject was undertaken in Canada by Dr. John George, his colleagues and graduate students at the University of Guelph, Guelph, Ontario. More recently, it seems that some very exciting work by Professor Rothe, who used pigeons in wind tunnels at Saarbrucken, Germany, reaffirmed the fact that, truly, fat is the main fuel involved in the production of energy for racing. Logically then, providing diets containing increased amounts of fat, could be very helpful in providing the highly important fuel reserves needed for racing, right? Well, possibly……

Perusal of available literature on the metabolism of protein, carbohydrate and fat in birds in general revealed some interesting information that could be very useful in preparing pigeons for racing. Here are some of the facts taken from pertinent scientific literature on birds.

Firstly, in birds, it is known that less than 4% of depot fat, that is, fat found in the body cavity, under the skin, etc., is actually produced in these locations. Where then, is the great majority of fat actually synthesized? Well, not surprisingly, in pigeons the liver is the major organ in which the vast amount of fat is produced.

In fact, in birds, about 47% of the fat produced for use in the body is produced in the liver, 44% in the carcass, 7% in the skin, and 2% in the intestines. It is known that when the relative weights of tissues are taken into account, the liver of birds is 20 times as active per unit of weight in the production of fat as is the carcass.

However, it is interesting to note as well that bone marrowis another important site for fat production in birds, and that bone marrow itself has about two thirds of the fat-producing activity of liver. After it is produced in the liver, fat is transported in the bloodstream to the body depots for storage, and very importantly, to working muscles where it serves as a ready fuel supply for sustained flight.

Fine so far, but there are a couple of interesting points to consider…. Logic would say that the addition of extra fat to the diet of racing pigeons would help the liver with production, and would just add to the amount of fat produced normally by the liver, and subsequently exported to storage sites.

In fact, one study several years ago showed that the addition of the vegetable oil, corn oil (a vegetable oil is simply a liquid fat) in the amount of 5% to the diet of racing pigeons, improved performances, especially from beyond 200 miles, whereas birds that were not supplemented with corn oil had poorer performances overall.

The addition of extra fat to the diet should assist the body in building fat reserves. My reading around the subject of the energy requirements of birds turned up some very interesting, surprising, and potentially useful information that could be of value in the preparation of pigeons for racing. The following facts need to be pondered, mulled over, and if judged to have some merit, acted upon accordingly:

Point #1 — high levels of fat in the diet of birds will DECREASE the amount of fat produced by the liver (Griminger, 1986).

Point #2 — high levels of protein in the diet of birds will DECREASE the amount of fat produced by the liver!!

Point #3 — high levels of carbohydrate in the diet of birds will INCREASE the amount of fat produced by the liver (Griminger, 1986).

In one study in chickens, it was found that the addition of 10% corn oil to the diet of young chicks actually decreased fat production in the liver by a startling 40%! However, it is important to note that when amounts of carbohydrate in the diet are held at a constant level, high levels of dietary fat don't interfere with fat production by the liver! Another important point is that stored fat in the body, including the flight muscles, is obtained not only from production in the liver, but also from fat absorbed from the diet through the wall of the intestines.

Now, let's try to translate some of this information so that it has a bit more meaning for fanciers. Firstly, the great majority of fat in the body of the racing pigeon is produced by the liver, from which it is then transported in the bloodstream to depots (also called storage areas), and to red fibers in the muscles, for direct use as a source of energy during flight.

Fat that is present the diet is also absorbed through the intestines and is transported to muscles and depot areas as well. As fat is needed by working muscle, it is mobilized from nearby sources and from these depots, and moved through the bloodstream to the muscles. Preferential use of fat by flight muscles allows for a more efficient liberation of energy during prolonged, strenuous flights such as those of migrating birds, and of racing pigeons.

There is some difference of opinion among fanciers as to whether depot fat is really utilized as a source of fuel. The information I have at this point is that experiments on pigeons at the University of Guelph showed that after a minimum of 30 minutes of exercise, the amount of fat in depots decreased by almost 25%, and that, correspondingly, the amount of fat in the breast muscles increased by about the same amount.

This work also demonstrated that the amount of fat in the bloodstream increased by about 18%, and in the liver, by about 30%. These investigations indicate to me that fat is indeed mobilized from depot areas, transported in the bloodstream, and taken up by the liver and working muscle.

It has been established in other species such as the laboratory rat that depot fat is not static, and that in this species, there is a complete recycling of depot fat every 10 days. Therefore, depot fat seems to be a dynamic system involved in the synthesis, oxidation, storage and release of fats in some species. Despite this general information, it is known that in pigeons, very little synthesis of fat occurs in depot areas.