Background: Artificial insemination (AI) has driven genetic progress in the dairy industry by facilitating intensive selection and use of the most elite sires. Despite rigorous assessments of sperm quality before semen is released, significant variation in field fertility still exists among bulls used in AI. There is anecdotal evidence internationally that mixing semen from more than one bull in the same semen straw (Heterospermic semen; HS) can protect against this variation and increase pregnancy rates, possibly due to sperm competition and/or allowing flexibility in timing of insemination relative to ovulation. HeteroBull aims to provide sound scientific evidence on the degree to which HS (both conventional and sex-sorted) can influence fertility and will establish the biological and molecular mechanisms underpinning this so that stakeholders can make informed decisions around its use.
Project Details: The overall objectives of the project are to:
· Assess the degree to which HS impacts pregnancy rates in lactating dairy cows and establish the bias towards individual bulls in the percentage of calves they sire in HS mixes.
· Quantify sperm function in HS mixes with a focus on capacitation, sperm transport, fertilisation rates and interaction with the female reproductive tract and establish the relationship to field fertility.
· Assess the role of seminal exosomes in sperm function with a focus on their miRNA cargo.
· Assess if HS increases the window during which cows can be inseminated, thereby increasing flexibility and facilitating once-a-day AI without comprising fertility.
· Evaluate if sex-sorted HS results in improved pregnancy rates compared to sex-sorted sperm from individual sires.
· Educate stakeholders on the role of HS in breeding programme.
This will be an exciting opportunity to immerse yourself in the world of animal reproduction. The successful candidates will join a highly motivated, internationally recognised, team of researchers and use cutting edge techniques in a project that straddles both basic and applied research.
Award: The stipend of €31,000 per annum includes university fees of up to a maximum of €6,000 and is tenable for 4 years (PhD positions) or 2 years (MSc position).
Candidate Attributes and Application Procedure
Candidates should have a high honours grade Bachelors in an Animal/Dairy Science, Veterinary Medicine, Biological Sciences, or related field with good knowledge of animal production systems. Interested candidates should submit an electronic copy of Curriculum Vitae and a letter of interest simultaneously to Prof. Sean Fair ([Email Address Removed]), Prof. Pat Lonergan ([Email Address Removed]) and Dr. Stephen Butler ([Email Address Removed]). The closing date for applications is December 20th 2023 with interviews in January 2024.