Evaluation of the influence of the homozygosity level and genomic inbreeding of Holstein and Black-and-White bull-producers on their own productivity indicators
DOI:
https://doi.org/10.7868/S3034519726010161Keywords:
dairy cattle, analysis of variance, sperm production, genomic inbreeding, homozygosity, FROH, Ca, FxAbstract
The study was conducted to assess the influence of the inbreeding coefficient (Fx) (n=207), the level of homozygosity (Ca) (n=207) and genomic inbreeding (FROH) (n=78) of Holstein and Black and White breeding bulls on the parameters of their own sperm production. With an increase in Fx, a tendency towards an increase in the average ejaculate volume is observed, accompanied by a decrease in the concentration of spermatozoa in the semen, which is especially noticeable when comparing the first group (1.43 billion/ml) with the subsequent ones (up to 1.3 billion/ml). The multiple correlation coefficient is 0.217, and the determination coefficient is 0.047, which indicates a moderate relationship between these parameters. Statistical significance at p=0.043 confirms the presence of a real influence of inbreeding on this parameter. Calculation based on STR markers shows that the average ejaculate volume tends to increase with the inbreeding level (from 4.46 ml to 5.19 ml); the sperm count in the ejaculate varies within the range of 6.23-7.06 billion; sperm concentration shows moderate fluctuations (1.29-1.41 billion/ml); semen activity remains consistently high (about 8 points). Thus, this indicates that even at high homozygosity levels (up to 77%), the main parameters of semen quality remain within the normal range. Analysis of variance shows that the sperm count in the ejaculate demonstrates a statistically significant dependence on the homozygosity level. According to SNP markers, sperm concentration has a very weak correlation with the homozygosity level (R=0.117), with no statistical significance at all (p=0.792). The average ejaculate volume shows a moderate correlation (R=0.249), but statistical significance was not achieved (p=0.187). Sperm activity demonstrates an extremely weak relationship (R=0.150) at p=0.635. Total sperm count shows a moderate relationship (R=0.189), but also without statistical significance (p=0.435). Across all samples, a reliable difference was noted between the studied groups according to Cochran's g-test using the G-test and the Bartlett's test at a significance level of а = 0.05. The reproductive potential of stud bulls was noted to be resistant to moderate levels of inbreeding. This allows for a more flexible approach to breeding issues, taking into account not only the degree of inbreeding, but also other selection parameters.
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Исследования выполнены по госзаданию №124020200029-4 (FGGN-2024-0013)
