Search

Background: The assessment of genetic diversity, population structure, as well as within and across breed relationships using DNA markers is essential to develop conservation and genetic improvement programs. Objective: To assess the genetic diversity and population structure of Criollo Lechero Tropical (CLT) and Romosinuano (ROMO) cattle breeds in Mexico and compare them with other Criollo and Spanish breeds. Methods: The study included CLT and ROMO genotypes from the 65k Axiom©BovMDv3 array. Genomic data of Criollo and Spanish breeds were retrieved from a repository. Genetic diversity across breeds was evaluated by pairwise Wright's FST, principal components, and structure analysis. Results: Observed and expected heterozygosity, inbreeding coefficient, and effective population size (Ne) were 0.31, 0.30, -0.018 and 56 in CLT, and 0.32, 0.31, -0.023 and 99 in ROMO, respectively. Wright's FST indicated that both breeds are related to American Criollo and some Spanish cattle. ROMO cattle showed more significant Spanish ancestry than CLT. Conclusions: This study presents novel evidence indicating that, although the Ne of these breeds is small, they are still diverse and can be used as genetic reservoirs in conservation programs. [ABSTRACT FROM AUTHOR]

Background: Two biotypes of Aberdeen Angus cattle breed, known as Old Type and New Type, that differ in their origin and beef production are formally recognized. In Colombia, this breed has been commercialized for approximately 80 years. Studies on the origin, kinship and levels of genetic diversity of this breed in Colombian herds are scarce, yet important for planning crossing and management strategies. Objective: To measure the genetic diversity and structure of two Colombian herds of Old Type and New Type biotypes of Aberdeen Angus from Huila and Cundinamarca provinces and assess mitochondrial introgression with other breeds. Methods: A set of ten microsatellites and sequences of the Mitochondrial Control Region were characterized. Estimators of genetic diversity and population differentiation along with tests of population assignment were applied. Results: Nuclear loci were highly polymorphic as shown by the Polymorphic Information Content (0.599) and the Probability of Identity (1.896 10-08). Both populations were highly diverse and clearly differentiated into two groups corresponding to the Old Type and New Type phenotypes. In contrast, mitochondrial data failed to distinguish these two groups and showed extensive admixture. Conclusions: This study optimized a set of ten highly polymorphic nuclear markers that may be used for parentage and population genetic studies of Aberdeen Angus. Genetic differentiation in these loci agreed with phenotypic differences of the Old and New Types. However, mitochondrial data indicated ancestry of multiple European breeds in the origin of Colombian Aberdeen Angus. [ABSTRACT FROM AUTHOR]

Preserving the genetic diversity of wild fish is an important consideration for restocking programs, as inbreeding can compromise progeny survival as well as impact the resilience of natural populations. Objective: To evaluate the influence of spawning method: semi-natural (SN) or strip-spawning (ST), and the number of breeders (1:3 and 2:6) on the reproductive efficiency and genetic diversity of B. orbignyanus progeny destined for restoration of wild stocks. Methods: Rates of fertilization, hatching and broodfish mortality were recorded. For genetic evaluations (allele frequency, observed and expected heterozygosity, Shannon index, inbreeding coefficient, molecular variance analysis, and genetic differentiation), breeders (n=24), and their progenies (90 larvae/treatment) were sampled and analyzed using eight microsatellite markers. Results: Higher fertilization and hatching rates, and lower broodfish mortality were observed for the SN method (p<0.05), whereas the number of breeders did not affect these parameters (p>0.05). Interaction between spawning method and number of breeders was not significant (p>0.05). The amplified microsatellite loci produced a total of 30 alleles, with sizes between 80 and 225 bp and their frequencies indicated an increase (p<0.05) of genetic diversity in the progenies, but low genetic differentiation between treatments (p>0.05). Conclusion: The spawning methods and number of breeders tested increased equally the genetic diversity of the progeny, with low genetic differentiation between treatments. In contrast, rates of fertilization, hatching and brood fish mortality revealed that the SN method resulted in the best reproductive efficiency due to the handling stress and injuries caused by ST. Thus, SN proves to be the most suitable spawning-method for B. orbignyanus in restocking programs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: The lack of information on population structure is one of the main obstacles to develop breeding and conservation programs for animal genetic resources. Objective: To characterize the population structure of Crioula Lageana cattle breed (Bos taurus) in order to assess its genetic diversity. Methods: Database with information of 1,638 Crioula Lageana animals, collected during 38 years, was analysed using the ENDOG v.4.4 program. Results: Effective population size ranged from 72.53 in complete generations to 143.90 in maximum generations. Inbreeding and Average Relatedness coefficients were 0.34 and 0.91%, respectively. The effective number of founders and ancestors were 29 and 28 animals, respectively, and only ten ancestors were responsible for 50% of the genetic variability of the whole population. The average generation interval was 5.84 years in the paternal line and 7.70 in the maternal one. Wright´s F statistics indicated low genetic distances between subsets in relation to the total population (Fst = 0.0015), between individuals with respect to their subpopulation (Fis = -0.0027), and between individuals in relation to the total population (Fit = -0.0012). Conclusion: Analysis of the population indicated that, despite the small number of animals with known parentage and considerable loss of genetic variability by the constant use of a few sires, and same value of number of founders and ancestors, the population showed good genetic management, low inbreeding, low genetic differentiation among subpopulations, and probably adequate effective population size for breed preservation. [ABSTRACT FROM AUTHOR]

Background: indigenous breeds are important for poor farmers because of their natural selection against harsh environments and adaptation to regional conditions. However, inbreeding of indigenous sheep populations has increased in Colombia due to indiscriminate cross-breeding with foreign animals and lack of reproductive controls, with subsequent loss in productivity, which poses a great risk for the conservation of valuable genes. Objective: to determine the genetic diversity in Colombian indigenous sheep by using a panel of 10 microsatellite molecular markers. Methods: blood samples from 362 individuals from 43 farms in 11 Colombian provinces were genotyped and analyzed for a panel of 10 microsatellite markers. Results: a total of 134 alleles were found (13.4 alleles/locus on average) with a range of observed and expected heterozygosity of 0.428 to 0.831 and 0.615 to 0.855, respectively, and 0.742 polymorphic information content (PIC). The average Wright F-statistics (FIS ) of the breeds was 0.107, suggesting moderate levels of inbreeding. Colombian sheep showed a low level of genetic differentiation among breeds (FST = 0.054) and STRUCTURE analysis showed complex patterns of admixture in the breeds. Conclusion: overall, Colombian sheep have high genetic variability, which is very important for future conservation programs and genetic improvement. [ABSTRACT FROM AUTHOR]

El ganado Senepol fue introducido en Colombia mediante el uso de la inseminación artificial y transferencia de embriones de un pequeño núcleo de los animales. Objetivo: estimar la variabilidad genética del ganado Senepol de Colombia por medio de marcadores microsatélites y estimar las frecuencias alélicas y genotípicas de SNPs en los genes que codifican para la calpastatina (CAST1), calpaína (CALP316) y leptina (PB). Métodos: 412 muestras de sangre de animales pertenecientes a 28 fincas fueron analizados para los STRs: INRA32, BM2113, ETH10, BM1824, INRA037, ETH225, INRA064, SPS115, TGLA126 y TGLA122 y los tres SNPs. Resultados: los microsatélites y los SNPs fueron polimórficos. El número de alelos de los microsatélites variaron entre 4 (BM1824) y 11 (INRA37), la heterocigosidad observada varió entre 0.21 (INRA64) y 0.89 (BM2113). La probabilidad de exclusión para el total de microsatélites fue mayor que 99.99%, indicando que el conjunto de microsatélites pueden ser usados para pruebas de filiación. Conclusiones: a pesar de ser una población pequeña y cerrada, este núcleo presenta una alta variabilidad genética y baja consanguinidad.O gado Senepol foi introduzido na Colômbia mediante o uso da inseminação artificial e a transferência de embriões de um núcleo pequeno de animais. Objetivo: estimar a variabilidade genética do gado Senepol da Colômbia mediante marcadores microsatélites e estimar as frequências alélicas e genotípicas dos SNPs dos genes de calpastatina (CAST1), calpaina (CALP316) e leptina (PB). Métodos: 412 amostras de sangue de animais pertencentes a 28 rebanhos foram analisadas para os STRs INRA32, BM2113, ETH10, BM1824, INRA037, ETH225, INRA064, SPS115, TGLA126 e TGLA122 e os três SNPs. Resultados: os microsatélites e os SNPs foram polimórficos. O número de alelos dos microsatélites variaram entre 4 (BM1824) e 11 (INRA37), a heterocigosidade observada variou entre 0,21 (INRA64) e 0,89 (BM2113). A probabilidade de exclusão para o total de microsatélites polimórficos foi maior que 99.99%, indicando que o conjunto de microsatélites podem ser usados para testes de filiação. Conclusões: embora seja uma população pequena e fechada, o núcleo apresenta uma alta variabilidade genética e baixa consanguinidade.The Senepol beef cattle breed was introduced into Colombia through the use of artificial insemination and embryo transfer from a small nucleus of animals. Objective: to estimate the genetic variability of Senepol cattle in Colombia by heterologous microsatellites and to estimate gene and genotypic frequencies of single nucleotide polymorphic markers through calpastatin (CAST1), calpain (CALP316), and leptin (PB) genes. Methods: 412 blood samples from 28 herds were genotyped for population genetic structure with the STR: INRA32, BM2113, ETH10, BM1824, INRA037, ETH225, INRA064, SPS115, TGLA126, and TGLA122 microsatellite markers. Three SNPs of calpastatin, calpain, and leptin genes were used. Results: all microsatellites and SNP markers were polymorphic. The number of alleles ranged from 4 (BM1824) to 11 (INRA37), and the observed heterozygosity varied between 0.21 (INRA64) and 0.89 (BM2113). Combined probability of exclusion for the microsatellites was higher than 99.99%, indicating the usefulness of this set of markers for parentage testing in Senepol. Conclusions: despite being a small and closed population, this nucleus presents high genetic variability and low inbreeding.