THE AMSTAFF EXPLAINED
PART 5
The Dog Breeder.
What you need to know if you intend to breed.
Linebreeding
Linebreeding is a form of inbreeding and is practiced in all forms of livestock management whether it is dogs, birds, tropical fish or otherwise. It is the only method of fixing desirable traits in our animals and removing undesirable ones. The closeness of linebreeding depends upon the type of animal and the trait to be fixed. A new colour mutation in a parrot, for example would see sons paired to their mothers and daughters paired to their fathers so the mutation can be preserved and to also map the mode of inheritance (all genes are either dominant, recessive or sex-linked) so that more of the mutation can be produced. This closeness of breeding is not usually practiced in dogs, however, close line breedings are usually between half brother and half sister who share the same father or are a grandfather to granddaughter. It can be seen from these two matings that in the first instance, of the half brother and sister that the intention is to bring together the two "halves" of the common parent while at the same time possibly making some improvement by introducing quality bitches into the line. In the second, the grandfather to granddaughter mating, the object is to take an excellent stud dog and by the careful breeding of his best daughter, breed his granddaughter back to him, either to maintain or improve quality. Less common practices are to breed uncles and nieces. This is what would be the outer limit of what could be called "close" linebreeding but only if the mating was back to the original stud dog. Close means we breed out from the original stud for one generation and then breed back to him, either directly as a grandfather/granddaughter or by the pairing of half brothers and sisters. Anything else is simply a breeding from the same line but the mating together of two dogs from the same line who are more distantly than those stated is an outcross. Take the grandchildren of a particular stud dog, for example. They have been bred on separate lines for two generations and the maximum of his blood will be 25% each - the maximum! When a breeding occurs, the genes will pair at random. In the original stud dog mating, each "child" will be guaranteed 50% of their father's genes which all pair with 50% of the genes from their mother. Follow that with another outcross and the results will be the offspring get a maximum 25% of their grandfather's genes but as the gene allocation is random, it may be possible to get No genes from their grandfather. To date there is no Dog Genome Map and the only way we have of determining how many genes the dog inherits from its parents is to use our eyes. Do they look like one parent or the other? Do they look like their famous grandfather or are they typical of the line? If not, the chances are that while a breeder can legally claim that a dog is from a particular line, it certainly does not possess many of the genes that made that line what it is. Close line breeding creates a degree of certainty whereas other methods do not. Do not be fooled by advertising hype where the genetics do not hold up.
Outcrossing
There are two reasons for outcrossing. The first and most important is to maintain vigour and fertility. As careful as one is, loss of fertility can occur in a single generation. The usual practice when line breeding is to outcross every third generation. The second reason is to improve the animal that you already have. Perhaps you have lost something in your line perhaps it was never quite as good as you had wanted and now, having carefully linebred and fixed many features, you wish to outcross to introduce another feature. Outcrossing introduces new genes to the pool which will enable a certain degree of genetic diversity. What is the best outcross? The first method of outcross practiced by the prudent breeder will be to sell the puppies they want to use at a later date to someone they know, preferably another breeder. By selling a daughter of their prize stud dog to a trusted friend with a compatible line, they can then introduce her to their line at a later date, thus creating the outcross. When the time comes to outcross yourself, not only are you outcrossing but re-introducing your own blood to a small degree thus minimising the chances of losing your line and maximising the chances of breeding winning pups in the first outcross generation. The second form of an outcross is where a completely unrelated stud dog is used. This is a complete outcross. There may be a number of reasons for this but such an outcross should be of outstanding quality. Only the breeder can say why he chose a particular dog. It may have been to introduce a particular feature prevalent in that line or simply as a means of upgrading the whole stud with linebreeding on the outcross planned in the future.
To cap off Line breeding improves or maintains the quality that has already been achieved and a linebred dog is always preferred. Outcrossing is used to maintain or improve fertility and improve quality in conformation. Any dog outcrossed more than once will have only between 0-25% of the original grandparent genes. Only by visual comparison can we judge the quality. There is much more that can be said on this subject and many have written books. Something I don't have the time to do but am more than willing to discuss with anyone interested.