Choosing Your Bison

J.C. Haigh

Reprinted from Game Farming Practice, Notes for the Game Farming Industry, 1987, GF-B-1-01

Summary

Whether you are an established bison rancher, or just getting into the industry, there are several basic criteria, apart from the obvious one of price, upon which you should base your selection of animals to come onto your property. These fall under the headings of breed, pedigree, health status, fertility and age. As with any other type of purchase, you tend to get what you pay for. I have seen some pretty terrible looking stock that were purchased when the buyer thought he was getting a great deal.

Breed

There are two breeds of North American bison. These are the wood bison, (Bison bison athabascae) and the plains bison (B.b.bison). The word bison is used in other parts of the world to describe various animals. The gaur is also known as the Indian bison, and the wisent is known as the European bison. Currently the wood bison is listed as an endangered species, and is not generally available for ranching (Note: since 1987 when this article was written the regulations have changed to allow the commercial farming of Woods bison in Canada). However there is one potentially commercial herd in Manitoba, and one other herd is currently under consideration for use in the commercial sense. It may be a long time before such animals become available on the market for sale to others. Meanwhile all the remaining bison in parks and on game ranches that are available on the market are of the plains variety .

There are differences between the two subspecies that are principally those of size.

Currently there is some scientific debate about the nature of such differences, but by and large the wood bison is a bigger animal than the plains bison.

Pedigree

It is necessary to put to rest the myth that bison lack genetic diversity and can be safely inbred. Dr. M. Koch has related one of the most obvious examples of the problems that can arise from inbreeding which is seen in the herd in the Badlands National Park in South Dakota. While the majority of the herd in the park have adequate genetic diversity, a small group were introduced from Colorado within the last 20 years. These bison were derived from two individuals that had had no genetic variability introduced and could be considered "in-bred". These animals look quite different from the established herd. The bulls are much smaller, are darker in color and have reddish hair on the shoulders and neck. The females are smaller and "lighter boned" than their counterparts from the main herd. A number of animals have been born with apparent congenital abnormalities. In the worst cases the lower leg is entirely absent. In less severe cases one leg is contracted and may not touch the ground. This is often associated with "slipper" hooves that may result from a lack of wear. Fig.3 overleaf illustrates such a case. Some of the bulls have kinked tails. Breeding of cows in the main herd by bulls from this

Colorado group has been observed. There is no proof that any of these deformities are truly hereditary .Nonetheless, it is at least reasonable to be suspicious.

The list above was kindly provided by Dr. Ken Throlson, a veterinarian and bison rancher from North Dakota. It summarizes the problems that he sees when inbreeding is practiced in a ranched herd.

Of the early signs of inbreeding reduced fertility and slower weight gains will only be spotted if good records are maintained by the farmer. The normal stance for bison is shown in Fig.l. The sloping back and slight "cow-hocked" appearance are evident. Rabbit leg (Fig.2) is a condition first recognized in Custer State Park. It is almost certainly a consequence of inbreeding. Animals that are badly effected show a "tucked-up" stance and have much thickened hocks, as well as a very light appearance in their hind quarters. The angle at which the hock bends is more marked in effected than in normal animals (compare Figs.l&2). Even if this appearance is masked when they stand still they may have real trouble walking or running. There will be no trouble distinguishing the normal from the "rabbit legged" animal once one has seen them move. It would obviously be unwise to purchase animals without having a "look-see".

While a deformity such as the contracted leg of the animals in the Badlands National Park (Fig.3) would be obvious to anyone, some of the others may be much more insidious, and a farmer could well lose large sums of money in reduced productivity without ever recognizing the cause.

Health status

One of the most important considerations in choosing your new bison will be their health status at the time of purchase and also when you move them onto your property. The time is not far off when the federal Health of Animals Branch will want to be sure that all animals on game farms are free of named diseases. The two principal concerns are brucellosis (Bang's disease) and tuberculosis caused by Mycobacterium bovis. If you intend to bring animals across the U .S. border they will be subject to the same stringent controls as would cattle and testing will be required for both of these diseases as well as for bluetongue and anaplasmosis.

Within Canada the situation is different as there are as yet no regulations related to animal health that govern the movement of live bison within this country .This may change but in any case the farmer would be well advised to carry out certain minimal precautions to ensure that healthy stock arrive on the farm.

It is generally recognized that disease in animals is not a simple entity involving the disease agent and the animal, but that the environment plays a key role in determining the outcome. If the bison you wish to buy come from overcrowded conditions and are to be subjected to a long and arduous journey between farms, then there is an increased likelihood that they will develop some sort of clinical problem either en route or in the short period of acclimatization after arrival. A few simple precautions may help to prevent some of these problems. The animals can be treated for parasites, vaccinated, and most important, some thought can be given to their nutrition. If you are buying from a reliable source most of these will have been dealt with ahead of time.

Parasites

Bison appear to be very hardy, but are certainly susceptible to a variety of parasitic diseases that can not only effect their productivity , but also lower their resistance to bacterial and virus conditions. It is a simple matter to administer an anthelmintic at the time of loading or unloading. There are several ways to do this.

The most efficient and surest would be to give an injectable anthelmintic such as Ivomec^TM or Tramisol^TM that you can administer accurately according to the animal's body weight. There are also anthelmintics that can be given by drench. Both of these methods presuppose that you have access to the animals in a chute. If this is not the case you may have to use anthelminitics in water or feed, both of which are possible, but not as reliable or accurate a method of administration.

Bison are also susceptible to coccidiosis, which can become a serious cause of disease in crowded conditions. The use of feed or water additives such as Amprol^TM will help to control this problem. Lice, ticks, and other external parasites can occur in bison and should be checked for. Fortunately many of these organisms are also susceptible to Ivomec ^TM. Warble flies are another parasite that can effect bison. One must be especially careful to avoid bringing infected animals into a "warble free" area. On the other hand there are risks attached to the use of warble treatments, especially late in the season. The best time to treat for warbles in cattle is in the fall, soon after the eggs have hatched and the larvae are just under the skin. Treatment at other times may be associated with severe reactions and even death of the animal. Presumably the same rules apply to bison, but none of the cattle preparations is likely to have been cleared for any other species, so caution must be taken.

Vaccination

The use of one of the commercially available clostridial vaccines is advisable, as these animals are susceptible to enterotoxemia and blackleg. Neither these or any other vaccines have been scientifically tested in this species, so as usual one can only suggest that they are likely to be of benefit. Most of the clostridial diseases tend to appear when animals are placed in stressful situations. Transportation, weaning and mustering could all qualify under this heading.

Nutrition

Any animal subjected to a sudden change in diet may have trouble digesting its food and may even develop severe enteric problems. The best system is to find out what your new bison have been eating and to stick to a similar diet for the first while. The basic bison diet is one of roughage, but just like cattle they can tolerate some form of concentrate. Many farmers "finish" them from 60-90 days on a pelleted or chop ration.

Fertility

Checking of males for semen quality has become a standard practice in many forms of livestock operation. While semen evaluation does not provide an absolute guarantee of fertility there is a very high correlation between breeding success and the quality of the ejaculate. In the field semen can be judged for its motility and density.  Further checking in a simple lab will permit the experienced evaluator to judge density more accurately and also count and evaluate individual sperm cells. Many established and beginning farmers are willing to take a chance on the type of bull that they put out with their cows.

Many times they may get away with it, but the relatively small price to pay for having a bull evaluated will save thousands of dollars in lost revenue if a dominant herd bull turns out to be sub-fertile, or perhaps even infertile. Semen collection and evaluation is very simple if there is an adequate chute system on the farm. All that the veterinarian needs beyond the chute is a warm sheltered room, with a few feet of bench space and an electric power source.

Evaluation of the bull is more important than that of the cows, because the consequences of one infertile male in a herd would obviously be much greater than that of a single infertile female. Nonetheless, pregnancy diagnosis is a simple and routine procedure that should be carried out on all females of breeding age. Again, an appropriate chute is a must. For the beginning farmer buying adult animals, it would be foolish to take any females other than those that have been checked and confirmed pregnant.

Age

One can readily debate the pros and cons of choosing bred cows or young stock with which to start up a farm operation. If you choose bred cows there are two things to remember. First, you are probably buying someone else’s cull animals, and second you have little or no idea of the age of the animal. If the vendor has good records and is trustworthy the best buy may well be a young, bred cow. In this way you have a return on investment in the first year, in the form of a calf. It will of course be another 2 years or so before anything is ready for slaughter.

If you choose to buy calves or heifers they may well be available at a lesser price than the adults. Moreover, you will be sure of age, and will be able to get the maximum commercial life out of the animals. In either case you should be sure to select a bull from a different blood line. Both sexes can breed as yearlings if they are exceptionally well nourished, but this would probably be a bad idea in the case of females as they are not physically mature at this age, and pregnancy will stunt their growth. The more common rule would be to breed them as 2 year olds. Bulls of this age will breed in herd situations and it has even been suggested that fully mature bulls cannot breed heifers very successfully because of the disparity in their sizes. It is usually the two and a half to three and a half year old bulls that are going to be slaughtered and by this age you will be able to judge growth and development and decide which bulls, if any, you wish to keep back as potential breeding stock, either for yourself or for sale to others.