Outcrossing.
Outcrossing is the term used in practice of mating stock that are unrelated.
The main object of outcrossing is to bring into the herd some desirable character which the herd lacks. For example, if a herd is low in butterfat, the surest method of improvement would be to use a bull which comes from a line noted for high butterfat, unless it is the management or feeding that is at fault. Cross-breeding can be used too but it will almost certainly add some characters that are not good.
Another reason for outcrossing is to restore some of the vigour that often found lacking where prolonged close-breeding has been practiced.
Inbreeding.
Inbreeding is the practice of mating very closely related animals. The use of inbreeding will result in the appearance of some poor animals, and the closer the mating the sooner they will appear. Hence, the inbreeding has to be accomplished by severe culling of the poorer stock to be effective as a breeding system. This is too expensive and few breeders can afford to improve their stock in this way. This method is widely used in poultry at present. Its possibilities are being increasingly explored in other classes of stock.
Line-Breeding.
Line-breeding is the practice of close-breeding where the animals are not closely related. In practice, line-breeding is the breeding back to a certain excellent sire or dam or to a family with which that sire or dam was associated. Good characters are preserved in this way and at the same time the relationship is not close enough to produce any of the ill effects of inbreeding.
Artificial insemination technique is known to be a valuable aid in carrying out various mating systems. As in this case semen can be frozen, transferred and kept for long periods to be used at any time in the future.
2. What sentences are true/false?
1. Most experiments convincingly prove that the crossing of breeds usually results in offspring that do not show more vigour and faster growth than their parents. 2. Careful selection of the most vigorous animals should be made for inbreeding to be a success as a breeding system. 3. The experiments with swine have shown that cross-breeding is an effective means of increasing the number of pigs per sow either at weaning time. 4. Most of the improvement of the type and performance of domestic animals has been done through the use of carefully planned breeding systems. 5. Unlike inbreeding line-breeding is the system of mating two unrelated individuals of the same breed.
3. Fill in the word-rose: Systems of breeding
cross - breeding
outcrossing
mating of animals of the same breeding line-Breeding
Inbreeding
4. Read the dialogue:
Breeder (on the sheep exhibition): Hello, Mr. Braun! You are looking for the best sheep breed for your farm again, aren’t you?
Client: Guessed! And what can you offer me again?
Breeder: Well, our sheep cross-breeding is one of the best examples of planned and efficient in Great Britain, you know.
Client: So, I’m interested in Scotch Blackface. What can you tell me about it?
Breeder: Scotch Blackface are very good mothers but they are rather small, and their lambs are not suitable for the fat lamb production.
Client: It’s clear. And I need sheep suitable for fat and meat production.
Breeder: Not for a long time this breed was crossed with a long-wool ram such as the Border Leicester and there is got successful fat and meat breed. I think it will be suitable for your production.
Client: May be.
Breeder: Scotch Blackface was imported from Australia to Britain and crossed with the Border Leicester breed. This combination has resulted in a new breed, which is better suited to Britain conditions for meat and wool production.
Client: Can you send me the information by fax or per internet, I’m interested in it, o.k.?
Breeder: It will be done after exhibition. Good buy!
Client: Good buy!