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.

Genetic diversity of bovine populations raised in Senegal

Background

The Gobra zebu and N'dama taurine cattle breeds are important genetic animal resources for Senegal. For several decades, genetic breeding programmes have been devoted to them at the Centre de Recherches Zootechniques de Dahra and Kolda. Since then, these animals have been subjected to mass selection, mainly in closed selection nuclei.

Objective

This study aims to assess the genetic diversity within these selection nuclei in order to orient future selection strategies.

Material and methods

The study was carried out on the Gobra zebu and N'dama taurine populations from selection nuclei of Dahra and Kolda respectively, which were compared to 5 other populations of the main cattle breeds in Senegal. One hundred eighty (180) animals were genotyped with 21 microsatellite markers recommended by the Food and Agriculture Organisation.

Results

All populations were found to be polymorphic with a PIC of over 55%. However, animals from the CRZ‐Dahra (indigenous) and CRZ‐Kolda stations had the lowest mean heterozygosity (0.643 and 0.591 respectively). The other populations had an average heterozygosity between 0.650 and 0.737.

Conclusion

The cattle populations maintained at the different CRZs show a lower genetic diversity than the other populations described in our study. The main reasons for this are reproductive isolation and selection pressure on these populations.

Evaluation of reproductive performance and genetic variation in bulls of the Polish White-Backed breed

The aim of the study was to evaluate genetic variation, reproductive performance and the degree of relationship of White-Backed bulls entered in the breed registry and approved for breeding. The study included 32 bulls of the White-Backed (WB) breed with an entry in the breed registry and used for breeding in the years 2003-2015. Eleven microsatellite DNA sequences (TGLA222, BM2113, TGLA53, ETH10, SPS115, TGLA126, TGLA122, INRA23, ETH3, ETH225 and BM1824) were used to analyse variation in the WB bulls. The bulls most often used for breeding were Chilon (1,073 doses), Mak (939 doses) and Jaguar (858 doses). The bulls Mak, Chilon and Jak had the greatest influence on the active population of White-Backed cattle, with the most daughters. In the analysed population of White-Backed bulls, a total of 79 different alleles were identified, with a mean 7.27 per locus. The analysed pool of microsatellite loci was characterized by high values for PIC, H_O and H_E (>0.6), and the entire population was in genetic equilibrium. The estimated level of inbreeding within the population ranged from -0.2277 (ETH225) to 0.0775 (SPS115), with a mean value of -0.0587.