![]() Semen quality and male fertility are complex traits with low to moderate heritabilities. A direct gene test can be implemented to monitor the frequency of the undesired allele in cattle populations. Routine sperm analyses unambiguously identify homozygous bulls for this allele. ConclusionsĪ recessive loss-of-function allele of the bovine QRICH2 gene likely causes low sperm concentration and immotile sperm with multiple morphological abnormalities. Semen analyses from the second bull confirmed low sperm concentration and immotile sperm with multiple morphological abnormalities that primarily affect the sperm flagellum and, to a lesser extent, the sperm head. Our analysis also identified another bull that carried the 1-bp deletion in the homozygous state. This haplotype segregates at a frequency of 5% in the Brown Swiss cattle population. The 1-bp deletion resides in a 675-kb haplotype that includes 181 single nucleotide polymorphisms (SNPs) from the Illumina BovineHD Bead chip. The analysis of testis transcriptomes from 76 bulls showed that the transcript with the premature termination codon is subject to nonsense-mediated mRNA decay. This 1-bp deletion causes a frameshift in translation and a premature termination codon (ENSBTAP00000018337.1:p.Cys1644AlafsTer52). ![]() Comparing the sequence variant genotypes of this bull with those from 397 fertile bulls revealed a 1-bp deletion in the coding sequence of the QRICH2 gene which encodes the glutamine rich 2 protein, as a compelling candidate causal variant. ![]() The genome of this bull was sequenced at a 12× coverage to investigate a possible genetic cause. This procedure identified a bull that produced 12 ejaculates with an aberrantly small number of sperm (0.2 ± 0.2 × 10 9 sperm per mL) which were mostly immotile due to multiple morphological abnormalities. We examined 70,990 ejaculates from 1343 Brown Swiss bulls to identify bulls from which all ejaculates were rejected due to low semen quality. Only ejaculates that fulfill minimum quality requirements are processed and eventually used for artificial inseminations. Semen quality and insemination success are monitored in artificial insemination bulls to ensure high male fertility rates.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |