In comparison to the cattle industry, relatively few sires undergo breeding soundness evaluations that include a sperm morphology assessment. Further, standard practice in the sheep industry is to categorise ram sperm as normal or abnormal, rather than assign specific types of abnormalities to each sperm cell. As a result, relatively little is known about the most common sperm abnormalities found in rams or whether specific types of abnormalities or what a ‘normal’ level of abnormalities can be expected within the ram population. As a result, this project will describe the levels of sperm abnormalities that can be expected in rams and compare them with baseline levels already established for cattle. It will establish the percentage of the ram flock with a level of sperm abnormalities above the current industry defined threshold of 15% as well as the Australian Cattle Veterinarians threshold of 30% (with specific sub category limits). This project will also produce a peer reviewed open access research publication.
This study will utilise fixed sperm samples from Merino rams collected from a range of sires across NSW (n = 400 animals). Samples will be analysed under a Olympus BX53 microscope with Differential Interference Contrast (DIC) optics at 400-1000x magnification. Cells will be photographed and categorised into 30 different abnormality types, which will allow subsequent categorisation into the Australian Cattle Vet 8 category system, Society for Theriogenology 4 category system, and current sheep industry 2 category system. Comparison will be made to frequencies of abnormalities obtained from fixed bull sperm samples (n = 400 animals) categorised in the same manner. Where possible, correlations will be made between abnormality type and breeding soundness evaluation outcomes (4Ts) as well as fertility data.