Kinship matching is based on the genetic relationship between mating parties. According to the degree of consanguinity between mating parties, it can be divided into inbreeding (referred to as inbreeding) and non-inbreeding (referred to as non-inbreeding). Generally speaking, cows that are related by blood within 5 generations are called inbreeding, otherwise they are called non-inbreeding. From the perspective of population genetics, under certain conditions, the gene frequency and genotype frequency of a large population should be relatively balanced between generations. If the environmental conditions of the next generation are the same, the quantitative average and standard deviation are basically the same. But if mating is not random, but opposite, it will upset this balance. The genetic relationship between matched individuals is higher than that of inbreeding in random mating, and the genetic relationship is lower than that of hybridization in random mating. Three, matching work should pay attention to several points.

1, each cattle farm must regularly formulate supporting plans that meet the breeding objectives of cattle, in which special attention should be paid to and prevention of inbreeding decline.

2. On the basis of investigation and analysis, select excellent breeding bulls according to the characteristics of each cow, that is to say, breeding bulls must be determined by their offspring, and breeding values or selection indexes such as milk yield, milk fat rate and appearance are higher than those of cows.

3, after each matching effect should be timely analysis and summary, and constantly improve the matching effect.