Rescuing Rare Pineywoods Cattle Strains 2005
D. P. Sponenberg
Some of the Pineywoods cattle strains are rare, and some are
close to extinction. In order to keep the genetic material from these available
to the breed, it will be important to rescue some of them.
For a strain to survive in genetic isolation,
necessary to have adequate numbers of animals in order to avoid inbreeding.
This is not always possible with very low numbers, and in some situations the
best that can be done is to include animals that are 3/4 or 7/8 the breeding of
the rare strain. In most situations it is all right to include any animal with
7/8 the breeding of a strain as a member of that strain. This is especially the
case if the other 1/8 of the breeding is from a related or similar strain.
Strategies for genetic
rescue vary, but need to be carefully
planned and thought if they are going to succeed. In most situations what
happens is rare strain cows are mated to common strain bulls, and their heifers
are once again mated to common strain bulls. The result is a constant reduction
in the genetics of the rare strain, instead of a concentration of it. A rescue
needs to do the opposite – concentrate the genetic contribution of the rare
A first, and frequently difficult, step to a rescue is to
assemble as many animals (usually cows) of the rare strain as can be found. 15
is a minimum, 20 is better. The rescue works best if a “same strain” bull is
available, but can also work if a “different strain” bull is all that is available.
Rescue Procedure When Same Strain Bull Is Available:
The original cows are all mated
to a bull of the same
strain. If multiple bulls from the strain are available, then the herd can go
directly into a strain conservation type breeding system, so this present
discussion will assume that only one bull is available. The result is a calf
crop that is 1/2 the strain of rescue interest. In all likelihood, two calf
crops will be produced, because the bull calves from the first calf crop will
not be available to use until a year old.
When the bull calves are old enough, use two of them on
different portions of the rare strain cows. What is usually most important is
to use them on old cows, as these frequently have the highest contribution of
the old original strain breeding. The dam of one bull calf can be mated to the
other bull calf, to minimize son-mother matings. Or, if space is limiting, then
mate one bull calf from the first calf crop in one year, and then the next year
use a second bull calf from the second year’s crop of calves.
This mating produces two different
calf crops, each 3/4 the
rescue strain, and 1/4 the other strain. When the 3/4 bulls are old enough, use
these back on the old cows for a 7/8 calf crop. Try to use two from one sire,
one from another, to give genetic distance among the 7/8 bull calves. At this
point, three relatively unrelated bulls can be saved. Each is 7/8 the rare
line, and these three can then be used sequentially in the herd in a
conservation breeding program. The “conservation and maintenance” strategy is
outlined in a separate article.
Rescue Procedure When No Bull
Available from the Strain
The situation in which only cows are available from a
strain, and no strain-pure bulls, is all too frequent. What usually happens in
this situation is to use a sequence of bulls from other strains on the herd.
The first generation calves are only 1/2 the original strain, the next
generation is only 1/4 the original strain. By this strategy the strain is
elminated fairly quickly, and replaced by the genetic material from the
introduced bulls. An effective rescue does the opposite, but is more difficult.
The first step is
to find a suitable bull from another
strain or line. Ideally this is a bull from another rare line, rather than from
one of the more common lines. This bull is used on the original cows. The calf
crop is 1/2 the rescue strain. Two bull calves are saved, either both in the
first year, or one in the first and one in the second year. The bull calves
should be selected on the basis of their type, but also any relationship
between their dams should be considered as well, because it is best to save
bulls from unrelated dams.
The 1/2 bulls are used when they are old enough (yearlings)
to sire a calf crop of 3/4 the rescue strain. Ideally three of the 3/4 bulls
are saved – one from one sire, two from the other. At this point it is possible
to begin a conservation breeding protocol, especially if the original cows
still have useful years ahead of them. If they are showing age, it is best to
split the herd and to use the 3/4 bulls all in the same year, just on different
portions of the herd. By that strategy it is possible to maximize the number
and genetic distance of the 7/8 calves that will result.
Rescuing the Single, Old Cow
In some situations strains can get to the point of
single or a very few old cows. Not much can be done to bring back these
strains. However, one good use of the old cow is to mate her to a son,
hopefully producing a 3/4 son. This is usually safe as far as the level of
inbreedng goes, and can provide most of the genetic material in the old cow for
wider use in a conservation composite. This is because bulls see more use than
cows and produce more offspring. In addition the bull should have semen frozen.
In some situations
it is also good to mate the 3/4 son back
to the original cow for a 7/8 son. This is pretty intense inbreeding, but for
unique old cows is still valuable. This technique was used by Justin Pitts to
provide Griffen Yellow bulls, and these have now spread the Griffen strain’s
genetic influence much further than would have otherwise been possible.
If two or three cows are available,
then the same sorts of
crosses can be used, but the sons of one can be used on the other old cows. This
still concentrates the genetic influence of the original cows, but does so with
less risk of inbreeding depression. With such low numbers it will be impossible
to regenerate an entire herd of the endangered strain, but it will be possible
to salvage much of it into a composite herd heavily influenced by the old, rare
Rescue Is Messy, but Essential
Recuing strains that are becoming extinct is satisfying when
it is finished – but it can be frustrating in the early stages. Strains that
need to be rescued are usually in situations where owners or breeders do not
have a high priority on conservation. That can make the initial location and
acquisition of breeding stock difficult to impossible. Patience and creativity
can help here!
After locating and acquiring the breeding stock, then it is
important to manage the stock well, and to mate them with specific goals in
mind. This can be awkward in some situations, but it essential if the long-term
genetic health of the strain is to be conserved. It is especially necessary to
keep the older cows in good shape in order to maximize the number of calves
they can have. The earliest stages of a rescue are essential, but the latter
stages are the point at which the older cows can have their maximal input. Each
situation is unique, and programs can be tailored to fit the requirements of