Seminal plasma proteins as early life indicators of male and female reproductive performance

Summary

This project set out to study the proteins present in the ejaculate of Bos indicus bulls and their relationship to bull fertility. The data for percent morphologically normal sperm at the time of the final semen sample collection via electroejaculation from all 2-year-old Beef CRC Brahman bulls branded in 2005 (n=176range 1.8 to 2.1 years), were collated into deciles, and then seminal plasma samples from 75 Brahman bulls were randomly selected. Two dimensional electrophoresis was used to produce maps (n=78) of the proteins present in the seminal plasma and the software PDQuest was used to quantify the expression (or amount) of each protein in 56 high quality maps. The identification of specific proteins was done by mass spectrophotometry.
Multi-level statistical modelling demonstrated that 8 specific proteins and their interactions accounted for 88% of total phenotypic variation in percent normal sperm. Several of these proteins have been previously shown to be significantly related to conception rate in Holstein bulls. The project was terminated early, however, as there was no suitable low cost and accurate method of defining the level of expression of these proteins in stored Beef CRC samples. Without such a method, it was not possible to estimate phenotypic and genetic correlations between these proteins and male and female reproductive traits.