Probability Of Gene Origin Research Articles

Genetic variability in three Italian beef cattle breeds derived from pedigree information

The aim of the present work was to estimate genetic variability in Chianina (CH), Marchigiana (MC) and Romagnola (RO) breeds using pedigree information. Different approaches based on probability of identity-by-descent (effective population size through an increase in inbreeding Ne) or probability of gene origin (total number of founders f, effective number of founders fe, ancestors fa and founder genomes fg) were used. Reference populations were defined using female animals born between 1996 and 2000 where both parents are known. Generation intervals were 5.35, 4.93 and 5.15 years for CH, MC and RO, respectively. The total number of founders were 7092, 11947, 3928, for CH, MC and RO, respectively. Complete generation equivalent showed the relative high quality of pedigree information: 5.66 for CH, 4.54 for MC and 4.95 for RO. For CH, MC and RO, respectively, a fe value of 152.1, 70.9 and 89.8, a fa value of 73.6, 48.0 and 59.5 and a fg value of 39.5, 25.0 and 38.5, were calculated. When inbreeding was used effective population sizes were 138, 122 and 124 for CH, MC and RO, respectively.Parameters derived from the probabilities of gene origin were variable among the investigated breeds and the results for MC demonstrate the need to pay specific attention to breeding strategies.

Structure and genetic variability in Nellore (Bos indicus) cattle by pedigree analysis

Parameters based on the probability of gene origin were used to describe the genetic variability in strains of Nellore and polled Nellore (Bos indicus) cattle that participated in the Program for Genetic Improvement of the Nellore Breed (Programa de Melhoramento Genetico da Raca Nelore). The effective number of founders was 87.2 for Nellore and 107.9 for polled Nellore, while the number of ancestors was 59.8 for Nellore and 61.5 for polled Nellore and the remaining genomes were 39.4 for Nellore and 34.5 for polled Nellore cattle. The results indicate an intense use (by artificial insemination) of some sires and the absence of subdivisions in the population. The family structure in the two breeds was mainly caused by the genetic contribution of the same sires and only mating preferences for descendants of some founders are recorded in either breed. The results suggest that genetic variability needs monitoring in order to avoid the compromise of genetic improvement in economically important traits in the breeding program.

Estrutura genética da raça Sindi no Brasil

O objetivo deste trabalho foi descrever a estrutura genética da raça Sindi no Brasil, utilizando dados do registro genealógico de animais nascidos entre 1955 e 1998. O banco de dados foi separado nos seguintes períodos: 1979-1983, 1984-1988, 1989-1993 e 1994-1998. A endogamia total aumentou de 0,38 para 10,13%; a esperada sob acasalamento ao acaso, de 0,07 para 5,65%; e a endogamia atribuída à subdivisão populacional, de 0,30 para 4,74%, considerando os períodos inicial e final, indicando a existência de subdivisão genética na raça Sindi. O tamanho efetivo populacional estimado pelo coeficiente total de endogamia decresceu vertiginosamente de 161 para 9. Tendo-se como base a probabilidade de origem do gene, foram calculados os números efetivos de fundadores, de ancestrais e de genomas remanescentes, os quais decresceram, ao longo do período total, atingindo valores de 16, 9 e 7, respectivamente.

Genetic variability of three Italian cattle breeds determined by parameters based on probabilities of gene origin

SummaryIn this study, we have investigated the genetic variability of three Italian cattle breeds, autochthonous of the Tuscany region (Chianina, Maremmana and Mucca Pisana), using the parameters based on probabilities of gene origin: f e, f a and N g. Compared with Chianina (N g=53.9) and Maremmana (N g=79.6), Mucca Pisana was found to be the genetically smaller (N g=10.1) and less diverse population. The genetic variability in Chianina population was lower than in Maremmana probably because of bottlenecks in its pedigree and genetic drift. However, the values found in these breeds were higher than those found in dairy cattle breeds, but lower than those found in beef cattle breeds.

Analysis of pedigrees of Tux‐Zillertal, Carinthian Blond and Original Pinzgau cattle population in Austria

The most common goal of animal conservation programmes is to maintain genetic diversity. Various measures for genetic variability based on pedigree information can be used, but most of them are very sensitive to completeness of pedigree information. Different criteria based on probability of identity‐by‐descent (effective population size via increase in inbreeding Ne) or probability of gene origin (effective number of founders fe, ancestors fa and founder genomes Ng) were used to describe the genetic variability of three Austrian cattle breeds [Original Pinzgau (PI), Tux‐Zillertal (TZ), Carinthian Blond (CB)]. Reference populations for PI were defined by animals born between 1993 and 1997 and for TZ and CB by all living animals, irrespective of birth year. The numbers of animals in the reference populations were 9706, 471 and 230 for PI, TZ and CB, respectively. The average complete generation equivalent showed the different quality of pedigree information: 5.33 for PI, 2.52 for TZ and 1.73 for CB. The following Nes were calculated: 76 for PI and CB and 43 for TZ. For PI, TZ and CB a fe‐value of 65.4, 21.0 and 29.9, a fa‐value of 32.1, 14.2 and 29.0 and a Ng‐value of 19.5, 9.7 and 22.6, respectively, were calculated. In particular, the results for TZ demonstrate the urgent need for a well‐planned conservation programme.

Genetic variability of populations and similarity of subpopulations in Austrian cattle breeds determined by analysis of pedigrees

AbstractParameters based on probabilities of gene origin were used to evaluate the genetic variability of four Austrian cattle breeds. Effective numbers of founders, ancestors and remaining founder genomes showed that all four populations investigated are rather small genetically. Effective numbers of remaining founder genomes were 94 for Simmental, 41 for Braunvieh (Brown Swiss), 32 for Pinzgauer and 21 for Grauvieh (Grey cattle, a small mountain breed). As the value of 94 for Simmental was rather large in comparison with estimates from other populations in previous studies, the effect of population structure was investigated. A cosine measure of similarity based on differences in individual founder contributions to different subpopulations was defined and used for analysis. Subpopulations defined by regions were clearly more distinct for Simmental than for Braunvieh. The size of the cosine values depended on the method of calculating founder contributions and was overestimated when choosing the method not accounting for drift and bottlenecks (effective number of founders).

Demographic characterization, inbreeding and maintenance of genetic diversity in the endangered Catalonian donkey breed

This study characterizes the demographic and genealogical structure of a limited-size population in danger of extinction: the Catalonian donkey breed. The purpose of this paper is to establish the most suitable breeding criteria and guidelines to achieve the 'Programme of Conservation and Maintenance of Animal Genetic Resources' in this population. The two main objectives proposed are: 1) to maintain the maximum genetic diversity, with 2) the minimum possible consanguinity increase per generation. A population size of 109 animals of both sexes, 44 males and 65 females, was analysed. The pedigree information was used to calculate the following items: generation length (L), variances of family size (o,2) k , effective population size (Ninbreeding coefficient (F) and probability of gene origin. The results obtained and breeding criteria to be followed are discussed. The correct mating policy between a stallion and a jenny would be that which would maximize the so-called genetic conservation index and minimize the inbreeding coefficient of the hypothetical offspring of the couple. © Inra/Elsevier, Paris