Recent development of allele frequencies and exclusion probabilities of microsatellites used for parentage control in the German Holstein Friesian cattle population

Ecuadorian Holstein-Friesian cattle paternal lineages: Demographic structure, inbreeding evolution, and genetic diversity

Holstein-Friesian cattle are the most important dairy breed worldwide. The main objective was to carry out a detailed pedigree evaluation of the Ecuadorian Holstein-Friesian cattle to investigate the demographic structure, inbreeding evolution, and genetic diversity of the official paternal lineages to determine the potential GD loss after the inclusion of modern Assisted Reproductive Technologies (ARTs). Official pedigree information from 28,893 Holstein-Friesian sires born between 1950 and 2021 and enrolled with the Ecuadorian Holstein-Friesian Association (AHFE, Ecuador) were recorded and evaluated from USA and Canada genetic official databases. After multiple-trait across-country genetic analyses the total population was divided into four subpopulations; i) 1950-1969: natural mating (NM) period; ii) 1970-1989: NM +  artificial insemination (AI) period; iii) 1990-2009: AI +  embryo transfer (ET) period; and iv) 2010-2021: AI +  ET +  genomic selection (GS) period. Demographic parameters [number of males, pedigree integrity (PI), and generation interval (GI)] were analysed. PI was analysed using known ancestors up to 4 generations considering the number of complete (GCom), maximum (GMax) and equivalent (GEqu) generations. Moreover, Inbreeding parameters [inbreeding coefficient (F), average relatedness (AR), coancestry (C), effective size (Ne), genetic conservation index (GCI)] and parameters related to the gene origin probability (number of founders (f), effective number of founders (fe), genetic conservation index (GCI), among others] were also analysed, together with the fe/f ratio, fge/fe ratio, genetic contributions, and genetic diversity loss (GD-loss) derived parameters. The results indicated that nearly all imported sires used in Ecuador born in the beginning of 1990s could be traced to just three countries, who together account for > 90% of paternal lineages. This fact indicates that GD has undergone a dramatic decrease during the past 30 years. The PCI for the three last periods were > 55%, and the trend was enhanced in the fourth chronological period till > 92%. The estimated proportion of random genetic drift in GD loss increased over time as well as the Ne that decreased by the time. In conclusion, the occurrence of AI +  ET +  GS period led to the major GD loss. Therefore, due to the extremely limited number of paternal lineages the strategy for recovering the minimal GD on the current and future Ecuadorian Holstein-Friesian cattle should reduce the inbreeding values by increasing the Ne using alternately the foreign genetic material and the national breeding stock.

Polymorphism analysis of tri- and tetranucleotide repeat microsatellite markers in Hanwoo cattle

The Hanwoo traceability system currently utilizes 11 dinucleotide repeat microsatellite (MS) markers. However, dinucleotide repeat markers are known to have a high incidence of polymerase chain reaction (PCR) artifacts, such as stutter bands, which can complicate the accurate reading of alleles. In this study, we examined the polymorphisms of the 11 dinucleotide repeat MS markers currently employed in traceability systems. Additionally, we explored four trinucleotide repeat MS markers and one tetranucleotide repeat MS marker in a sample of 1,106 Hanwoo cattle. We also assessed the potential utility of the tri- and tetranucleotide repeat MS markers. The polymorphic information content (PIC) of the five tri- and tetranucleotide repeat markers ranged from 0.663 to 0.767 (mean: 0.722), sufficiently polymorphic and slightly higher than the mean (0.716) of the current 11 dinucleotide repeat markers. Using all 16 markers, the mean PIC was 0.718. The estimated probability of identity (PI) was 3.13 × 10-12 using the 11 dinucleotide repeat markers, 7.03 × 10-6 using the five tri- and tetranucleotide repeat markers, and 2.39 × 10-17 using all 16 markers; the respective PIhalf-sibs values were 2.69 × 10-9, 1.29 × 10-4, and 3.42 × 10-13; and the respective PIsibs values were 3.89 × 10-5, 9.6 × 10-3, and 3.69 × 10-7. The probability of exclusion1 (PE1) was 0.999864 for the 11 dinucleotide repeat markers, 0.981141 for five of the tri- and tetranucleotide repeat markers, and > 0.99 for all 16 markers; the respective PE2 values were 0.994632, 0.901369, and > 0.99; and the respective PE3 values were 0.998702, > 0.99, and > 0.99. The five investigated tri- and tetranucleotide repeat MS markers can be used in combination with the 11 existing MS markers to improve the accuracy of individual identification and paternity testing in Hanwoo.

Determination of declined genetic diversity of Holstein stud bulls based on microsatellite markers

Semen importing countries are trying to select the most suitable studs according to their breeding goals, while the globally widespread use of common genetic material has been turning the loss of genetic diversity into a possible danger. The aim of this study was to evaluate the genetic diversity of 304 high-yielding Holstein stud bulls whose semen were produced in Turkiye, Europe and the Americas. The values of allele frequencies, expected heterozygosity (He), observed heterozygosity (Ho), Hardy-Weinberg (HW) Equilibrium, the number of alleles per locus (Na), allelic richness (Rs), polymorphic information content (PIC) and F-statistics were calculated and compared the results with similar studies. It was observed that some indicator values of the genetic diversity were decreased compared to the values of the other studies in Holstein breed. Especially the decrease in some values of SPS115 locus was statistically significant. It is thought that this could be as a result of SPS115 to be close to possible QTL regions associated with traits which indicates overall potential of selection in stud bulls. Therefore, while applying a selection program to populations, national genetic resource management strategies that maintain genetic diversity should not be forgotten besides gaining high yield.

Analysis of Genetic Variability in the Argentine Polo Horse With a Panel of Microsatellite Markers

Argentine Polo (AP) is a young horse breed with a fast expansion because of an open registry policy and the application of assisted reproduction technologies. In the last years, AP showed a remarkable progress associated with the use of embryo transfer technology and intensive selection based on sport performance. However, these practices could have affected the genetic variability of the breed. To monitor these potential changes, a parentage panel of 11-15 microsatellites was investigated for changes in allele frequencies, heterozygosity, and exclusion probability over a 16 year period. Frequency of 36 alleles in 13 markers showed significant departures from expected changes because of random genetic drift. Six markers showed both allelic frequency increase and expected heterozygosity (He) reduction, suggesting the influence of selective breeding or hitchhiking effects. The average He decreased significantly although was lower than the observed heterozygosity, indicating a still low inbreeding level. Although the exclusion probability of the panel showed a trend to decrease, it is over 0.9995, the recommended value for equine parentage exclusion.

Genetic Diversity of Historical and Modern Populations of Russian Cattle Breeds Revealed by Microsatellite Analysis

Analysis of ancient and historical DNA has great potential to trace the genetic diversity of local cattle populations during their centuries-long development. Forty-nine specimens representing five cattle breeds (Kholmogor, Yaroslavl, Great Russian, Novgorod, and Holland), dated from the end of the 19th century to the first half of the 20th century, were genotyped for nine polymorphic microsatellite loci. Using a multiple-tube approach, we determined the consensus genotypes of all samples/loci analysed. Amplification errors, including allelic drop-out (ADO) and false alleles (FA), occurred with an average frequency of 2.35% and 0.79%, respectively. A significant effect of allelic length on ADO rate (r² = 0.620, p = 0.05) was shown. We did not observe significant differences in genetic diversity among historical samples and modern representatives of Kholmogor and Yaroslavl breeds. The unbiased expected heterozygosity values were 0.726–0.774 and 0.708–0.739; the allelic richness values were 2.716–2.893 and 2.661–2.758 for the historical and modern samples, respectively. Analyses of F_ST and Jost’s D genetic distances, and the results of STRUCTURE clustering, showed the maintenance of a part of historical components in the modern populations of Kholmogor and Yaroslavl cattle. Our study contributes to the conservation of biodiversity in the local Russian genetic resources of cattle.

Evaluation of recent changes in genetic variability in Japanese thoroughbred population based on a short tandem repeat parentage panel

The integrity of thoroughbreds is maintained under strict regulation involving DNA parentage testing, which is robust in a population with high genetic variability. The genetic variability of the thoroughbred population is possibly fluctuating because of selective breeding that has focused on adaptations for racing performance. To monitor genetic variability within the population and the effectiveness of short tandem repeat (STR) parentage testing, we investigated allele frequencies and the exclusion probability (PE) of 16-17 loci of a parentage panel in the Japanese thoroughbred population over 15 years. Expected heterozygosities (He) of 14 loci indicated a decreasing trend, and the average He of the population decreased significantly. Low genetic variability was possibly induced by a decrease in population size and a selective breeding bias. Four loci showed both a significant increase in allele frequency and a significant decrease in He; it is assumed that those loci were affected by positive selection for racing performance. There was a significant decrease in the PE because of the changes in genetic variability; however, it has remained over 0.99995. The current STR panel is still effective for parentage control, but it will be necessary to continuously monitor genetic variability, which has decreased over 15 years.

Evaluation of 24 microsatellite markers for parentage exclusion in three indigenous pig types of India

A set of 24 FAO recommended microsatellite markers was evaluated for parentage exclusion (PE) in three Indian pig types of Assamese, North-Indian and Ankamali. The genomic DNA from these three Indian pig types was amplified at these loci by polymerase chain reaction and resolved for alleles. The allelic frequency data was analysed to calculate the probability of paternity exclusion when one of the parents is to be excluded (PE1), when both the parents are to be excluded (PE2) and when only one parent is known and that is to be excluded (PE3) in these three Indian pig types using a set of minimum 5 loci and then increasing the number of loci in increments of 5 upto maximum of 24 loci. The cumulative PE1 values taking into consideration all the 24 loci varied from 1-2.07×10-10 in North Indian pigs to 1-3.95×10-11 in Ankamali pigs. The cumulative PE2 values taking into consideration all the 24 loci varied from 1-4.57×10-16 in Assamese pigs to 1-3.17×10-18 in Ankamali pigs. Similarly, cumulative PE3 values for all the 24 loci varied from 0.9999968 in Assamese pigs to 0.99999955 in Ankamali pigs. The cumulative PE values obtained, even with a set of 15 loci (CGA, IGF1, S0005, S0026, S0068, S0090, S0155, S0178, S0215, S0218, S0228, S0355, SW122, SW911, SW936), were clearly more than the required value of 0.9995 in all the three breeds with the minimum value of 0.99985 for PE3 in Assamese pigs. Clearly, this set of 15 loci or the sets with 20 or 24 loci can be safely employed for parentage exclusion purposes in the Indian pigs.