Individual multilocus genotypes using microsatellite polymorphisms to permit the analysis of the genetic variability within and between Italian beef cattle breeds1

Abstract

We investigated the genetic variability within and between cattle breeds. The polymorphisms of 17 microsatellites were studied in 220 unrelated animals belonging to four Italian beef cattle breeds (Chianina, Marchigiana, Romagnola, and Piemontese). Variations of allelic frequencies were examined to characterize the breeds and their relationships. Wahlund coefficients, Polymorphism Information Content values, and Haldane exact test for Hardy-Weinberg proportions were calculated. The results show that the Hardy-Weinberg equilibrium is not always maintained. Moreover, in addition to the classical genetic distances, a new method, based on the consideration of a multilocus genotype of each animal, was set up to measure the genetic similarity between animals or within groups of animals. All the results showed that, whereas Chianina occupies an intermediate position and Piemontese is the most distinct of all four breeds, Marchigiana and Romagnola display the strongest similarity. The new method also provides evidence that average similarities are always higher within breeds than between breeds. By comparing pairwise the multilocus genotypes, it was also possible to discriminate the individuals with higher or lower genetic similarities so that each breed could be subdivided into two groups of animals in relation to their similarity to the average breed multilocus genotype. High similarities between breeds were detected, somewhat surprisingly, when the most homogeneous groups of each breed were compared. The microsatellite multilocus genotype is particularly efficient in evaluating the between- and within-breeds genetic similarities and for subgrouping genetically more homogeneous animals.

Study of genetic distances between cattle breeds of Central Europe

“…Hansen et al (2002), evaluating the genetic distances between Canadian breeds based on microsatellites, emphasized the difficulty in scientifically estab- lishing unique breeds. In the preservation of gene reserves, Ciampolini et al (1995) considered the use of microsatellites as effective for the study of genetic similarity both within and between breeds and for the detection of genetically homogeneous subgroups. Kim et al (2002), evaluating genetic diversity based on 13 microsatellites using DA distance and N-J tree, found the group of Chinese and Korean cattle, the Japanese Black cattle was clearly distinct.…”

Measuring genetic distances between breeds: use of some distances in various short term evolution models

“…In order to measure the genetic distances between closely related populations like breeds, it is desirable to use highly polymorphic markers such as microsatellites [3,4,9,15,18,24,37,40,53,59,60,70].…”

“…, c 1 and c 2 in Nei and Chakravarty [50], may be respectively approximated by (1 − F) 3 , (1 − F) 6 , 9 5 and 1 5 in Chevalet and Gillois [8] and setting µ k = i p k 0,i and…”

Investigation on the genetic variability of the american Pit Bull Terrier dogs belonging to an Italian breeder using microsatellite markers and genealogical data

“…Genetic similarities of animals were investigated by comparing the individual multilocus genotype of each individual with each other [16]. Genetic similarity is defined as P = A/2L, where P is the proportion of common alleles (A) in relation to the 2L possibilities (L -number of considered loci).…”