Dairy Cow Reproduction
Why is this research important?
Systems of milk and beef production are under increasing scrutiny linked to animal welfare issues, environmental challenges, minimising waste and delivering excellent quality and nutritious food products to consumers. The health and welfare of male dairy calves represents a major reputational risk to the industry. These calves present a particular problem in seasonal-calving systems, when large numbers of male dairy calves are born in a short period of time, saturating a small market. Appropriate use of reproductive technologies can help to address some of these challenges, and improve the sustainability of milk and beef production.
What the research tells us
Sexed semen
In November 2021, Sexing Technologies established a sexing laboratory at Teagasc Moorepark, with the primary objective of stimulating greater availability of sex-sorted semen from more high EBI bulls. The sex-sorting service was available to all AI companies operating in Ireland. For the 2022 breeding season, the laboratory at Moorepark produced 85,000 straws during a 5-month period. For the 2023 breeding season, Sexing Technologies started sorting at Moorepark in September 2022, and opened a second sexing laboratory at the National Cattle Breeding Centre (NCBC) in November 2022. The combined output of the two laboratories for the 2023 breeding season was approximately 230,000 straws. Further modest growth in sex-sorted semen production is expected for the 2024 breeding season. Research work is continuing in this area to identify optimal practices for sexed-semen usage in dairy heifers and cows.
The use of “beef on dairy” has been a recent topic of growing interest in many countries. Gestation and parturition are necessary for the initiation of lactation, but in all dairy herds, the total number of calves born is greater than the required number of replacement females. Hence, in most herds, ≥60% of the calves born are destined for beef production, despite the fact that the genetic background of many of these calves was selected for dairy production. Increased use of sex-sorted semen to produce replacement heifers means that a smaller proportion of the herd needs to become pregnant with dairy semen to provide the required number of female dairy calf births, facilitating more beef semen usage on the dams that are deemed unsuitable for generating replacements.
In vitro produced (IVP) embryos to accelerate genetic gain
When the majority of dairy farmers use sex-sorted semen on the best genetic merit dams to meet the replacement heifer requirements for the herd, an intended consequence is a reduction in male dairy calves, but an unintended consequence is a potential deceleration in genetic gain in the national herd, as the number of elite male dairy offspring will be diminished. This means that the next generation of elite male dairy calves will need to be generated in an organised and planned manner.
The systematic use of strategies to multiply the number of offspring using embryo technologies has important applications for both dairy and beef breeds. The available embryo technologies include Multiple Ovulation and Embryo Transfer (MOET) or Oocyte Pick-Up and In Vitro Embryo Production (IVP). For dairy, increasing the number of offspring from elite dairy donors could help to maintain or accelerate genetic gain for dairy traits in the face of declining numbers of male dairy calves as a result of widespread adoption of sex-sorted dairy semen for generating replacements. For beef, increasing the number of offspring from elite beef donors could help to accelerate genetic gain in the Dairy Beef Index. The combination of these collective gains will improve the sustainability of both dairy and beef production.
Outputs
Sexed semen
Research papers
Review papers about sexed semen and IVP embryos
- Review: Use of assisted reproduction in seasonal-calving dairy herds
- Invited review: Use of assisted reproduction techniques to accelerate genetic gain and increase value of beef production in dairy herds
Webinars
Contacts
Stephen Butler (stephen.butler@teagasc.ie)
Rachel Doyle (rachel.doyle@teagasc.ie)