Evaluation of selection program by assessing the genetic diversity and inbreeding effects on Nellore sheep growth through pedigree analysis

Objective: The main objectives of the present study were to assess the genetic diversity,population structure and to appraise the efficiency of ongoing selective breeding program in the closed nucleus herd of Nellore sheep through pedigree analysis.Methods: Information utilized in the study was collected from the pedigree records of Livestock Research Station, Palamaner during the period from 1989 to 2016. Genealogical parameters like generation interval, pedigree completeness, inbreeding level, average relatedness among the animals and genetic conservation index were estimated based on gene origin probabilities. Lambs born during 2012 and 2016 were considered as reference population. Two animal models either with the use of Fi or ∆Fi as linear co-variables were evaluated to know the effects of inbreeding on the growth traits of Nellore sheep.Results: Average generation interval and realized effective population size for the reference cohort were estimated as 3.38±0.10 and 91.56±1.58, respectively and the average inbreeding coefficient for reference population was 3.32%. Similarly, the effective number of founders, ancestors and founder genome equivalent of the reference population were observed as 47, 37, and 22.48, respectively. Fifty per cent of the genetic variability was explained by 14 influential ancestors in the reference cohort. The ratio fe/fa obtained in the study was 1.21, which is an indicator of bottlenecks in the population. The number of equivalent generations obtained in the study was 4.23 and this estimate suggested the fair depth of the pedigree.Conclusion: Study suggested that the population had decent levels of genetic diversity and a non-significant influence of inbreeding coefficient on growth traits of Nellore lambs. However, small portion of genetic diversity was lost due to a disproportionate contribution of founders and bottlenecks. Hence, breeding strategies which improve the genetic gain, widens the selection process and with optimum levels of inbreeding are recommended for the herd.

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Estructura Genética de la Población de Llamas (Lama glama del Banco de Germoplasma del Instituto Nacional de Innovación Agraria -Perú

Revista de Investigaciones Altoandinas - Journal of High Andean Research ◽

10.18271/ria.2016.178 ◽

2016 ◽

Vol 18 (1) ◽

pp. 55

Author(s):

Rubén Mamani Catoa ◽

Roberto Gallegos Acero ◽

Teodosio Huanca Mamani ◽

Juan P Ablo Gutiérrez

Keyword(s):

Genetic Structure ◽

Reference Population ◽

Critical Value ◽

Inbreeding Coefficient ◽

Gene Bank ◽

Effective Number ◽

Effective Population ◽

Generation Interval ◽

Average Ratio ◽

Lama Glama

RESUMENEl objetivo del estudio fue evaluar la estructura genética de la población de llamas, del Banco de Germoplasma de Quimsachata Estación Experimental Illpa-Puno del Instituto Nacional de Innovación Agraria, durante el año 2015<a href="#_msocom_1">[h1]</a> <a href="#_msocom_2">[h2]</a> . Se analizó el archivo de pedigrí de 4698 animales nacidos en el periodo 1993 al 2014, de los cuales 2075 fueron machos y 2623 hembras<a href="#_msocom_3">[h3]</a> . Para el cálculo de los coeficientes individuales de consanguinidad (F), coeficiente de relación media (AR), tamaño efectivo de la población (Ne), de fundadores (fe) de ancestros (fa), intervalo generacional (IG) y la profundidad de pedigrí se ha utilizado el programa ENDOG v.4.8. Los resultados para coeficiente de consanguinidad media y el promedio de relación media de la población de llamas fueron 0.11 y 0.25% respectivamente. Del total de 906 ancestros que dieron origen a la población de referencia, 102 explican el 50% de la variabilidad genética de la población. El número efectivo de fundadores fue 508 y de ancestros 284. El intervalo generacional medio fue 5.65 años, siendo mayor en las vías gaméticas padre-hijo y padre-hija. Para el grado de profundidad de pedigrí fueron identificados 65.88% de animales con información sobre los padres y 83.95% sobre las madres. El tamaño efectivo de la población fue de 281.81, este valor está por encima del valor crítico. En conclusión la consanguinidad en la población de llamas del banco de germoplasma fue de pequeña magnitud y que las prácticas de apareamiento fueron adecuadas durante el periodo evaluado. ABSTRACTThe objective of the study was to describe the genetic structure of the population of llama’s gene bank National Institute of Innovation Agrarian INIA-Puno. The pedigree file of 4698 animals born in the period 1993 to 2014, of which 2075 were males and 2623 females were analyzed. For the calculation of individual coefficients of inbreeding (F), coefficient average ratio (AR), effective population size (Ne), of founders (fe) of ancestors (fa), generation interval (IG) and depth of pedigree has been used ENDOG v.4.8 program. The results for inbreeding coefficient average and average mean ratio of the population were 0.11 and 0.25 flames% respectively. Of the total of 906 ancestors that gave rise to the reference population, 102 account for 50% of the genetic variability of the population. The effective number of founders and ancestors was 508 284. The average generation interval was 5.65 years, being higher in the gametic roads father-son and father-daughter. For the degree of depth of pedigree they were identified 65.88% of animals with information about parents and 83.95% on mothers. The effective size of the population was 281.81, this value is above the critical value. In conclusion inbreeding in the population of llamas gene bank was small in magnitude and mating practices were adequate during the period evaluated.<div><hr align="left" size="1" width="33%" /><div><div> </div></div></div>

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Population Structure Analysis of the Border Collie Dog Breed in Hungary

Animals ◽

10.3390/ani9050250 ◽

2019 ◽

Vol 9 (5) ◽

pp. 250 ◽

Cited By ~ 5

Author(s):

Virág Ács ◽

Árpád Bokor ◽

István Nagy

Keyword(s):

Genetic Diversity ◽

Reference Population ◽

Inbreeding Coefficient ◽

Pedigree Data ◽

Effective Population ◽

Inbreeding Coefficients ◽

Population Structure Analysis ◽

Dog Breed ◽

Fixation Indices ◽

Mixed Line

Pedigree data of the Border Collie dog breed were collected in Hungary to examine genetic diversity within the breed and its different lines. The database was based on available herd books dating from the development of the breed (in the late 1800s) to the present day. The constructed pedigree file consisted of 13,339 individuals, of which 1566 dogs (born between 2010 and 2016) composed the alive reference population which was active from breeding perspective. The breed is subdivided by phenotype, showing a thicker coat, harmonic movement, a wide skull, and heavier bones for the show type, and a thinner or sometimes short coat and smaller body for the working line, while the mixed line is quite heterogeneous (a combination of the above). Thus, the reference population was dissected according to the existing lines. The number of founders was 894, but eight individuals were responsible for contributing 50% of the genetic variability. The reference population had a pedigree completeness of 99.6% up to 15 generations and an inbreeding coefficient of 9.86%. Due to the changing breed standards and the requirements of the potential buyers, the effective population size substantially decreased between 2010 and 2016. Generation intervals varied between 4.09 and 4.71 years, where the sire paths were longer due to the later initial age of breeding in males compared to females. Genetic differences among the existing lines calculated by fixation indices are not significant; nonetheless ancestral inbreeding coefficients are able to show contrasts.

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Analysis of Genetic Diversity in the Czech Spotted Dog

Animals ◽

10.3390/ani10081416 ◽

2020 ◽

Vol 10 (8) ◽

pp. 1416

Author(s):

Karolína Machová ◽

Anita Kranjčevičová ◽

Luboš Vostrý ◽

Emil Krupa

Keyword(s):

Genetic Diversity ◽

Population Size ◽

Effective Population Size ◽

Reference Population ◽

Pedigree Analysis ◽

Inbreeding Coefficient ◽

Random Genetic Drift ◽

Effective Population ◽

Founding Population ◽

The Mean

Loss off genetic diversity negatively affects most of the modern dog breeds. However, no breed created strictly for laboratory purposes has been analyzed so far. In this paper, we sought to explore by pedigree analysis exactly such a breed—the Czech Spotted Dog (CSD). The pedigree contained a total of 2010 individuals registered since the second half of the 20th century. Parameters such as the mean average relatedness, coefficient of inbreeding, effective population size, effective number of founders, ancestors and founder genomes and loss of genetic diversity—which was calculated based on the reference population and pedigree completeness—were used to assess genetic variability. Compared to the founding population, the reference population lost 38.2% of its genetic diversity, of which 26% is due to random genetic drift and 12.2% is due to the uneven contribution of the founders. The reference population is highly inbred and related. The average inbreeding coefficient is 36.45%, and the mean average relatedness is 74.83%. The effective population size calculated based on the increase of inbreeding coefficient is 10.28. Thus, the Czech Spotted Dog suffered significant losses of genetic diversity that threaten its future existence.

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Trends in genetic diversity and the effect of inbreeding in American Angus cattle under genomic selection

Genetics Selection Evolution ◽

10.1186/s12711-021-00644-z ◽

2021 ◽

Vol 53 (1) ◽

Author(s):

Emmanuel A. Lozada-Soto ◽

Christian Maltecca ◽

Duc Lu ◽

Stephen Miller ◽

John B. Cole ◽

...

Keyword(s):

Genetic Diversity ◽

Beef Cattle ◽

Genomic Selection ◽

Inbreeding Depression ◽

Growth Traits ◽

Effective Population ◽

Angus Cattle ◽

Genomic Inbreeding ◽

Chromosome Segments ◽

The Impact

Abstract Background While the adoption of genomic evaluations in livestock has increased genetic gain rates, its effects on genetic diversity and accumulation of inbreeding have raised concerns in cattle populations. Increased inbreeding may affect fitness and decrease the mean performance for economically important traits, such as fertility and growth in beef cattle, with the age of inbreeding having a possible effect on the magnitude of inbreeding depression. The purpose of this study was to determine changes in genetic diversity as a result of the implementation of genomic selection in Angus cattle and quantify potential inbreeding depression effects of total pedigree and genomic inbreeding, and also to investigate the impact of recent and ancient inbreeding. Results We found that the yearly rate of inbreeding accumulation remained similar in sires and decreased significantly in dams since the implementation of genomic selection. Other measures such as effective population size and the effective number of chromosome segments show little evidence of a detrimental effect of using genomic selection strategies on the genetic diversity of beef cattle. We also quantified pedigree and genomic inbreeding depression for fertility and growth. While inbreeding did not affect fertility, an increase in pedigree or genomic inbreeding was associated with decreased birth weight, weaning weight, and post-weaning gain in both sexes. We also measured the impact of the age of inbreeding and found that recent inbreeding had a larger depressive effect on growth than ancient inbreeding. Conclusions In this study, we sought to quantify and understand the possible consequences of genomic selection on the genetic diversity of American Angus cattle. In both sires and dams, we found that, generally, genomic selection resulted in decreased rates of pedigree and genomic inbreeding accumulation and increased or sustained effective population sizes and number of independently segregating chromosome segments. We also found significant depressive effects of inbreeding accumulation on economically important growth traits, particularly with genomic and recent inbreeding.

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Effect of inbreeding and individual increase in inbreeding on growth in Nilagiri and Sandyno breeds of sheep

Animal Genetic Resources/Ressources génétiques animales/Recursos genéticos animales ◽

10.1017/s2078633615000338 ◽

2016 ◽

Vol 58 ◽

pp. 63-71 ◽

Cited By ~ 1

Author(s):

R. Venkataramanan ◽

A. Subramanian ◽

S.N. Sivaselvam ◽

T. Sivakumar ◽

C. Sreekumar ◽

...

Keyword(s):

Growth Traits ◽

Inbreeding Coefficient ◽

Pedigree Information ◽

Research Station ◽

Sheep Breeding ◽

Inbreeding Coefficients ◽

Equivalent Number ◽

Breeding Research ◽

Percent Increase ◽

Two Populations

SummaryIndividual increase in inbreeding coefficients (ΔFi) has been recommended as an alternate measure of inbreeding. It can account for the differences in pedigree knowledge of individual animals and avoids overestimation due to increased number of known generations. The effect of inbreeding (F) and equivalent inbreeding (EF) calculated fromΔFi, on growth traits were studied in Nilagiri and Sandyno flocks of sheep. The study was based on data maintained at the Sheep Breeding Research Station, Sandynallah. The pedigree information and equivalent number of generations were less in Sandyno compared with Nilagiri sheep. The average F and EF for the Nilagiri population were 2.17 and 2.44, respectively and the corresponding values for Sandyno sheep were 0.83 and 0.84, respectively. The trend of inbreeding over years in both the populations indicated that EF was higher during earlier generations when pedigree information was shallow. Among the significant effects of inbreeding, the depression in growth per 1 percent increase in inbreeding ranged from 0.04 kg in weaning weight to 0.10 kg in yearling weight. In general, more traits were affected by inbreeding in Nilagiri sheep, in which greater regression of growth traits was noticed with F compared with EF. Higher values of EF than F in earlier generations in both the populations indicate that EF avoided the potential overestimation of inbreeding coefficient during recent generations. In the Sandyno population, the magnitude of depression noticed among growth traits with significant effects of inbreeding was higher. The differences in response to F and EF noticed in the two populations and possible causes for the trait wise differences in response to F and EF are appropriately discussed.

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Population structure of Czech cold-blooded breeds of horses

Archives Animal Breeding ◽

10.5194/aab-54-1-2011 ◽

2011 ◽

Vol 54 (1) ◽

pp. 1-9

Author(s):

L. Vostrý ◽

Z. Čapková ◽

J. Přibyl ◽

B. Hofmanová ◽

H. Vostrá Vydrová ◽

...

Keyword(s):

Population Structure ◽

Genetic Variability ◽

Population Size ◽

Effective Population Size ◽

Inbreeding Coefficient ◽

Effective Population ◽

The Czech Republic ◽

Generation Interval ◽

Average Value ◽

Inbreeding Coefficients

Abstract. In order to estimate effective population size, generation interval and the development of inbreeding coefficients (Fx) in three original breeds of cold-blooded horses kept in the Czech Republic: Silesian Noriker (SN), Noriker (N) and Czech-Moravian Belgian horse (CMB) all animals of the particular breeds born from 1990 to 2007 were analysed. The average values of generation interval between parents and their offspring were: 8.53 in SN, 8.88 in N and 8.56 in CMB. Average values of effective population size were estimated to be: 86.3 in SN, 162.3 in N and 104.4 in CMB. The average values of inbreeding coefficient were 3.13 % in SN stallions and 3.39 % in SN mares, in the N breed 1.76 % and 1.26 % and in the CMB breed 3.84 % and 3.26 % respectively. Overall averages of Fx were: 3.23 %, 1.51 % and 3.55 % for the breeds SN, N and CMB. The average value of inbreeding coefficient Fx increased by 1.22 % in SN, by 0.35 % in N and by 1.01 % in CMB, respectively. This may lead to a reduction in genetic variability. Reduction in genetic variability could be either controlled in cooperation with corresponding populations of cold-blooded breeds in other European countries or controlled by number of sires used in population

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Using pedigree information to study genetic diversity and re-evaluating a selection program in an experimental flock of Afshari sheep

Archives Animal Breeding ◽

10.5194/aab-55-375-2012 ◽

2012 ◽

Vol 55 (4) ◽

pp. 375-384 ◽

Cited By ~ 6

Author(s):

F. Ghafouri-Kesbi

Keyword(s):

Genetic Diversity ◽

Phenotypic Selection ◽

Reference Population ◽

Pedigree Information ◽

Selection Experiment ◽

Founder Population ◽

Effective Number ◽

Effective Population ◽

Breeding Values ◽

Closed Population

Abstract. The purpose of this paper was to evaluate the inbreeding consequences of a short-term selection experiment which was initiated in 1998 in an Afshari sheep flock. Moreover, the conducted selection experiment was re-evaluated through assessing change in ranking of the first 10 influential ancestors when their genetic contributions were replaced with their breeding values. A total of 1714 animals were registered in the herdbook with a founder population comprised of 243 animals. The average coancestry (f) and inbreeding (F) in the reference population were 2.1% and 1.2%, respectively. Estimated value of the effective population size (Ne) was 50. The effective number of founders (fe) was estimated to be 40 and the effective number of ancestors (fa) was 34. Estimates of breeding values revealed that owing to phenotypic selection some ancestors with lower breeding values had greater contribution to the reference genome than those with greater breeding values and, for this reason, the population has been deprived from the maximum genetic improvement that could be achieved if selection was based on breeding values. The effective number of founder genomes (fg) was computed to be 23 and the effective number of non-founder genomes (fne) was 55. The index of genetic diversity decreased by almost 2.2% over the period studied. In general, decrease in genetic variability was low and Ne was not very low for a small-closed population under selection, indicating even in populations which undergo selection, besides achieving genetic gain, the rate of inbreeding is controllable if matings carefully planned.

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Genetic parameters for growth rate and Kleiber ratios of Nellore sheep

Indian Journal of Animal Research ◽

10.18805/ijar.b-3380 ◽

2018 ◽

Author(s):

I. Satish Kumar ◽

G. Gangaraju ◽

C. Vijaya Kumar ◽

Sapna Nath

Keyword(s):

Andhra Pradesh ◽

Growth Traits ◽

Average Daily Gain ◽

Genetic Correlations ◽

Research Station ◽

Genetic Progress ◽

Stages Of Growth ◽

Kleiber Ratio ◽

Nellore Sheep ◽

Daily Gain

Data on growth traits of Nellore sheep were extracted from the records maintained at Livestock Research Station, Palamaner, Andhra Pradesh, India for a period of five years. The genetic and phenotypic parameters were estimated for growth traits i.e., average daily gain (ADG) from birth to 3 months (ADGa), 3 months to 6 months (ADGb), 6 to 12 months (ADGc) and the corresponding Kleiber ratio (KR) at respective stages of growth. The non genetic factors included in the model were having significance on most of the traits studied. The heritability estimates for ADG and corresponding KR ranged from 0.17 to 0.25. The estimates of genetic correlations among the traits ranged between -0.28 (Ka-Kb) and 0.99 (ADGb-Kb). The moderate estimates of heritability, high and positive genetic correlations among the traits in the study were suggestive of moderate genetic progress in the Nellore breed of sheep through selection.

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Evaluation of the Romosinuano cattle population structure in Mexico using pedigree analysis

Revista Colombiana de Ciencias Pecuarias ◽

10.17533/udea.rccp.v32n4a05 ◽

2020 ◽

Vol 33 (1) ◽

pp. 44-59

Author(s):

Rafael Núñez-Domínguez ◽

Ricardo E Martínez-Rocha ◽

Jorge A Hidalgo-Moreno ◽

Rodolfo Ramírez-Valverde ◽

José G García-Muñiz

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Gene Flow ◽

Population Size ◽

Effective Population Size ◽

Genetic Drift ◽

Pedigree Analysis ◽

Effective Population ◽

Genetic Management ◽

Generation Interval

Background: Romosinuano cattle breed in Mexico has endured isolation and it is necessary to characterize it in order to facilitate sustainable genetic management. Objective: To assess the evolution of the structure and genetic diversity of the Romosinuano breed in Mexico, through pedigree analysis. Methods: Pedigree data was obtained from Asociación Mexicana de Criadores de Ganado Romosinuano y Lechero Tropical (AMCROLET). The ENDOG program (4.8 version) was used to analyze two datasets, one that includes upgrading from F1 animals (UP) and the other with only straight-bred cattle (SP). For both datasets, three reference populations were defined: 1998-2003 (RP1), 2004-2009 (RP2), and 2010-2017 (RP3). The pedigree included 3,432 animals in UP and 1,518 in SP. Demographic parameters were: Generation interval (GI), equivalent number of generations (EG), pedigree completeness index (PCI), and gene flow among herds. Genetic parameters were: Inbreeding (F) and average relatedness (AR) coefficients, effective population size (Nec), effective number of founders and ancestors, and number of founder genome equivalents. Results: The GI varied from 6.10 to 6.54 for UP, and from 6.47 to 7.16 yr for SP. The EG of the UP and SP improved >63% from RP1 to RP3. The PCI increased over time. No nucleus or isolated herds were found. For RP3, F and AR reached 2.08 and 5.12% in the UP, and 2.55 and 5.94% in the SP. For RP3, Nec was 57 in the UP and 45 in the SP. Genetic diversity losses were attributed mainly (>66%) to genetic drift, except for RP3 in the SP (44%). Conclusions: A reduction of the genetic diversity has been occurring after the Romosinuano breed association was established in Mexico, and this is mainly due to random loss of genes.Keywords: effective population size; gene flow; genetic diversity; genetic drift; generation interval; inbreeding; pedigree; population structure; probability of gene origin; Romosinuano cattle. Resumen Antecedentes: La raza bovina Romosinuano ha estado prácticamente aislada en México y requiere ser caracterizada para un manejo genético sostenible. Objetivo: Evaluar la evolución de la estructura y diversidad genética de la raza Romosinuano en México, mediante el análisis del pedigrí. Métodos: Los datos genealógicos provinieron de la Asociación Mexicana de Criadores de Ganado Romosinuano y Lechero Tropical (AMCROLET). Los análisis se realizaron con el programa ENDOG (versión 4.8) para dos bases de datos, una que incluyó animales en cruzamiento absorbente (UP) a partir de F1 y la otra con sólo animales puros (SP). Para ambas bases de datos se definieron tres poblaciones de referencia: 1998-2003 (RP1), 2004- 2009 (RP2), y 2010-2017 (RP3). El pedigrí incluyó 3.432 animales en la UP y 1.518 en la SP. Los parámetros demográficos fueron: intervalo generacional (GI), número de generaciones equivalentes (EG), índice de completitud del pedigrí (PCI), y flujo de genes entre hatos. Los parámetros genéticos fueron: coeficientes de consanguinidad (F) y de relación genética aditiva (AR), tamaño efectivo de la población (Nec), número efectivo de fundadores y ancestros, y número equivalente de genomas fundadores. Resultados: El GI varió de 6,10 a 6,54 para la UP, y de 6,47 a 7,16 años para la SP. El EG de la UP y la SP mejoró >63%, de RP1 a RP3. El PCI aumentó a través de los años, pero más para la SP que para la UP. No se encontraron hatos núcleo o aislados. Para RP3, F y AR alcanzaron 2,08 y 5,12% en la UP, y 2,55 y 5,94% en la SP. Para RP3, Nec fue 57 en la UP y 45 en la SP. Más de 66% de las pérdidas en diversidad genética se debieron a deriva genética, excepto para RP3 en la UP (44%). Conclusiones: una reducción de la diversidad genética ha estado ocurriendo después de que se formó la asociación de criadores de ganado Romosinuano en México, y es debida principalmente a pérdidas aleatorias de genes.Palabras clave: consanguinidad; deriva genética; diversidad genética; estructura poblacional; flujo de genes; ganado Romosinuano; intervalo generacional; pedigrí; probabilidad de origen del gen; tamaño efectivo de población. Resumo Antecedentes: A raça bovina Romosinuano tem estado praticamente isolada no México e precisa ser caracterizada para um manejo genético sustentável. Objetivo: Avaliar a evolução da estrutura e diversidade genética da raça Romosinuano no México, através da análise de pedigree. Métodos: Os dados genealógicos vieram da Asociación Mexicana de Criadores de Ganado Romosinuano y Lechero Tropical (AMCROLET). As análises foram feitas com o programa ENDOG (versão 4.8) para duas bases de dados, uma que incluiu animais em cruzamento absorvente (UP) a partir da F1 e a outra base de dados somente com animais puros (SP). Para ambas bases de dados foram definidas três populações de referência: 1998-2003 (RP1), 2004-2009 (RP2) e 2010-2017 (RP3). O pedigree incluiu 3.432 animais na UP e 1.518 na SP. Os parâmetros demográficos foram: intervalo entre gerações (GI), número de gerações equivalentes (EG), índice de completude do pedigree (PCI), e fluxo de genes entre rebanhos. Os parâmetros genéticos foram: coeficiente de consanguinidade (F) e da relação genética aditiva (AR), tamanho efetivo da população (Nec), número efetivo de fundadores e ancestrais, e número equivalente de genomas fundadores. Resultados: O GI variou de 6,10 a 6,54 para a UP, e de 6,47 a 7,16 anos para a SP. EG da UP e a SP melhorou >63%, de RP1 a RP3. O PCI aumentou ao longo dos anos, mas mais para a SP do que para o UP. Não se encontraram rebanhos núcleo ou isolados. Para RP3, F e AR alcançaram 2,08 e 5,12% na UP, e 2,55 e 5,94% na SP. Para RP3, Nec foi 57 na UP e 45 na SP. Mais de 66% das perdas em diversidade genética foram ocasionadas pela deriva genética, exceto para RP3 no UP (44%). Conclusões: Depois que a associação da raça Romosinuano foi estabelecida no México, tem ocorrido uma redução da diversidade genética, principalmente devido a perdas aleatórias de genes.Palavras-chave: consanguinidade; deriva genética; diversidade genética, estrutura populacional; fluxo de genes; intervalo entre gerações; pedigree; probabilidade de origem do gene; Romosinuano; tamanho efetivo da população.

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Pedigree-based analysis of genetic variability in the registered Normande cattle breed in Colombia

Animal Production Science ◽

10.1071/an15057 ◽

2017 ◽

Vol 57 (3) ◽

pp. 422

Author(s):

Derly Rodríguez Sarmiento ◽

Emanuela Tullo ◽

Rita Rizzi

Keyword(s):

Genetic Diversity ◽

Genetic Variability ◽

Population Size ◽

Cattle Breed ◽

Inbreeding Coefficient ◽

Mating Strategies ◽

Effective Population ◽

Significant Difference ◽

Genealogical Information ◽

Over Time

Genetic variability and structure of the population were studied in 7949 registered Normande cattle in Colombia. The pedigree was deep with 18 traced generations, but there were some incomplete genealogical information for the cattle born in the more distant past. The average number of complete and equivalent complete generations was 2.42 and 5.21, respectively. The average pedigree completeness index for five generations was 0.62, which increased over time, and a significant difference between sexes was found (males: 0.82 ± 0.11; females: 0.62 ± 0.38). The average generation interval was 7.57 years. The number of founders, effective founders, ancestors, and founder genomes were 575, 115, 47, and 22.22, respectively, which suggests that an unequal use of founders and a random loss of alleles from founders occurred over time. The level of inbreeding was 0.019 and increased to 0.023, when the inbreeding coefficient was calculated by assigning inbreeding of contemporaries to founders. These levels of inbreeding lead to an effective population size of 138.5 and 117.9 and to a 0.36% and 0.42% rate of inbreeding, respectively. Out of 267 herds with more than five registered breeding animals, only one nucleus herd was present, whereas 117 and 119 were classified as multiplier and commercial herds, respectively. About 92% of calves were sired by French bulls; but the use of Colombian bulls for breeding is increasing. The Colombian Normande breed is at an acceptable level of genetic variability, although some losses of founder alleles have occurred. As the level of inbreeding has been increasing, inbreeding and mating strategies should be monitored in order to maintain the genetic diversity of the breed.

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