Overview of Clinical Cytogenetics in Mammalian Livestock

Whilst balanced chromosomal aberrations, often do not present phenotypically in carriers they are known to cause reduced fertility in livestock. Mammalian livestock are of vital economic importance with pigs and cattle providing over 50% of consumed meat globally. Furthermore, cattle are the main providers of a dairy industry worth over $750 billion. In an industry where a small population of high value males (boars/bulls/rams) are used in the vast majority of artificial insemination, the potential financial loss caused by a sub-fertile male could be considerable especially if aberrations are passed down to offspring. This thesis reports on recent data collected using novel Multiprobe® Fluorescent in situ Hybridisation (FISH) devices on porcine and bovine blood samples for robust systematic screening of chromosomal abnormalities. There is significant potential for widespread use of these devices as they offer a more sensitive and accurate approach than given with previous methods such as karyotyping. Using this method 775 pigs and 3 cattle were screened. We reported that 14.5% of screened pigs presented with 8 different types of abnormality which is a far higher prevalence then previously recorded by karyotyping. 2 of 3 cattle samples also presented with an abnormality. Our results showed that poor quality of many samples received in 2021-2022 due to delivery complications meant that translocations were undetectable using a standard karyotype. However, FISH works well even with sub-optimal sample quality meaning time and money would not be lost in the repeating of sample collection and delivery. Multiprobe® device analysis is a comprehensive, robust system in bovine and porcine samples therefore, there is potential for it to work in other livestock species. This thesis reports on the use of probes selected for the bovine Multiprobe® device to test the extend they will bind to ovine (sheep) chromosomes to potentially create a novel ovine Multiprobe® device.