4. Breeding methods in cattle production 소의 육종 기술

B3 Breeding methods in cattle production: purebred breeding, crossbreeding

Breeding Systems

• Natural: Harem (group of 1-2 males and number of females with their offspring), stud (such as a stud farm) or hand (Hand breeding – where the time & mating individuals are selected by the breeder)
• Beef production
• Sex ratio = 40-50 (60-79)
• ​AI- artificial insemination:
• Predominantly used in dairy industry
• Sex ratio = 150-200 (single ejaculation. Deep-frozen semen)

Breed: A breed population is characterized by common breeding history, reproduction unit & common breed characteristics.

Population has common gene pool.

Inheritable characteristics passed on from parents to offspring.

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Pure breeding

• Selective breeding, the breeding of two individuals in the same breed in order to reach the desired characteristics and traits in the offspring
• Increases allelic frequencies of favorable (desired) characteristics (inbreeding, linebreeding)
• Preservation of allelic frequencies as high as possible (maintenance breeding, gene preservation)​

Cross- breeding

• The mating of two individuals that are different breeds within the same species
• Introduction of specific single (major) genes  polled, horns etc.
• (breed improvement by introducing new genetic material  grading up, crossbreds)
• New breed establishment (composites, synthetic breeds)
• Combination o f different additive genetic traits (fertility of maternal lines & gain of paternal lines = milk production & daily gain)

Heterosis (hybrid vigor):

• Midparent heterosis: Difference between the hybrids and the mean of the two parents
• Profit heterosis: The advantage of hybrids is calculated in another trait
• Individual heterosis: In that it quantifies hybrid vigor attributable to heterozygosity of the same outbred individuals upon whom the traits were measured
• Maternal heterosis: Hybrid advantage due to heterozygosity in the dams of the individuals being measured, e.g. crossed sows have better maternal behaviour then straightbred sows.
• Paternal heterosis: An effect on offspring phenotype of crossed (outbred) versus
• in- (random) bred sires – common and important economically in pig.

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Common crossbreeding systems

Terminal cross

• 2 or more breeds are crossed in an organized sequential system with the final cross going to slaughter (complexity increases as more breeds are used)
• Sire used must provide genes for good growth rate & carcass merit to suit the market demand

​Two breed cross (terminal)

• Requires a female herd of a particular breed ✏ One part is used to breed replacement, purebred females, the rest are used to produce crossbred progeny which are sold for slaughter (or females are used by another, F1 breeder)

​Back cross

• One of the two parent breeds is mated back to the F1. Lends itself to consistent product production.

​Three breed cross (terminal)

• Requires min. 3 breeding paddocks
• One purebred herd is used to breed purebred replacements One herd produces F1 cows
• F1 animals breed terminal slaughter animals

Rotational cross (continous crossing)

• Best uses & optimizes hybrid vigour & complimentary characteristics Purebred bulls of 2+ breeds are used in sequential rotation over crossbred females

​Composite (synthetic) breed: All crossbreeding systems require the continuous input of purebred animals.​

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Breeding programs

• Goal: Systematic production of breeding & commercial animals of defined pedigree & production traits
• Involves breeding associations & organizations
• Corner points & requirements for successful breeding programs
• Breeding population
• Marking of animals & Identification
• Safety of descent & origin of animals
• Guaranteed by mating, parturition, bloodgroups, DNA analysys

performance & progeny testing

Reproduction techniques:

• AI, embryo transfer, MOET [multiple ovulation embryo transfer]

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Breeding value estimation

Breeding goals: Breeding programs can lead to breed improvement

• Embryo transfer
• MOET (multiple ovulation and embryo transfer)
• Cloning

Performance testing for breeding

• Milk performance
• Meat performance
• Reproductive performance
• Fertility
• Calving ease
• Health
• Milking ability
• Conformation
• Hereditary disorder