Speaking at today’s Moorepark ’19 event, Teagasc’s Donagh Berry outlined results of recent research on sexed semen; the work was carried out by Teagasc’s Stephen Butler in 2018.
“These results are from 150 herds where they have been bred to sexed semen and conventional semen to oestrus, but also to timed AI,” Donagh explained.
“These were also a select group of cows within those herds; so, younger cows that are at least 50 days calved by the time of insemination.
“On those herds we are seeing a conception rate of around 60% to the conventional semen, and what we call a relative conception rate of 85% for sexed, so that equates to a conception rate of 50%.”
Continuing, he said: “If you are not achieving these particular statistics, the numbers are less. Also, we know that there is considerable variability in the conception rate for sexed semen, but what we noticed – based on the data so far – is that the variability can be quite substantial when it comes to sexed semen.
“So really you need to get all your ducks in a row before you can consider using the sexed semen approach,” he added.
Example
“Let’s assume on a 100-cow herd, you want 20 heifers to calve down in 24 months’ time, so you are looking at around 25 heifers born.
“So, to achieve these 25 heifers born, what you’re looking at is about 83 conventional straws to give your – assuming the 60% conception rate – 25 dairy females and 25 dairy males.
“If you look at it from a sexed semen perspective, you’d be looking at using 56 sexed semen straws – because not every single straw is guaranteed to give you a heifer – there’s a 90% chance of a heifer.
“And then you could use 27 beef straws. That will equate to 25 dairy females and three dairy male calves on average – because sexed semen is not 100% going to give a female dairy calf and 17 beef animals,” he concluded.