Sexing Technologies recently announced that it will be opening a sexed semen lab, which will be operational from November 1, with straws available from spring 2022.

Speaking at the dairy open day at Teagasc Moorepark, Stephen Butler, a researcher with Teagasc stated that: “This is going to increase the team of bulls available for sexed semen use along with the economic breeding index (EBI) value of the bulls available.

“So this means sexed semen can be used to increase the rate of genetic gain within the national herd.”

Stephen stated: “To obtain the best genetic gain you need to use sexed semen on the top half of the herd in terms of EBI value.

“This will mean that some cows can be allocated sexed semen from day one of the breeding season, while some cows will be allocated beef semen from day one of breeding.”

Sexed semen

There have been a number of trials to compare the conception rates of sexed vs. conventional semen.

In these studies, sexed semen was about 84% as good as conventional semen and it did not matter which breeding protocol was used (fixed time artificial insemination [AI] or observed heat) – the results were similar.

Some of the factors that affected the conception rates are parity, days in milk, body condition and EBI.

So, if sexed semen is targeted for the use in the more fertile animals, sexed semen is 94% as good as conventional semen.

Calf crop

The use of sexed straws will have the biggest impact on the calf crop produced by the national dairy herd each year.

Based of 2020 figures, 27% of calves born each year are female dairy calves, 27% are male dairy calves and 46% are beef calves.

By using sexed straws to generate replacements, these figures would change to 27% for female dairy calves, 3% for male dairy calves and 70% for beef calves.

Genetic gain

The use of sexed semen within the national herd will become increasingly more popular, but how will we continue to obtain genetic gain within the national herd?

The problem with using sexed straws is there will be fewer high-value bulls calves available for use in AI.

So, how do we continue to obtain maximum genetic gain within the national herd, while also increasing the use of sexed semen?

Stephen stated: “There will be fewer male dairy calves, about 3% of births each year. But this means there will be fewer male dairy calves that will be suitable for use as AI bulls.

“We need to develop a strategy to continue the genetic gain within the national herd.”

A trail was developed to evaluate new technology: “This [technology] involves taking elite donors – your elite cows and heifers and each week – [and] these cows are scheduled for oocyte collection.

“These oocyte are then brought to a lab and in-vitro fertilization (IVF) is conducted. After fertilisation an embryo is produced, with these being cultured for seven days.

“After the seven days of growing/producing this embryo in lab, the viable embryos are selected and transferred in recipients (cow or heifer) – that are also on day seven of their cycle.”

Stephen stated that: “This does involve a lot of planning. But the big advantage of this is you can have a large number of breedings between elite cows/heifers and bulls.

“The trial has seen a similar rate of success to conventional AI. Oocyte collection will help to produce high genetic value bulls for use in AI.”