Farmer Focus: Hoping sexed semen lifts herd genetics
© Cathal Noonan “If you’re not experimenting, you’re not learning” is a phrase that’s alive and kicking on our farm at times. The decision to go 100% sexed semen this year wasn’t taken lightly.
Our starting point was to ask how many replacement heifers we needed. We have a settled herd and target a replacement rate of 18-20%, allowing for mishaps.
The main downside to sexed semen is a conception rate of only about 50%.
As we run a spring calving grass-based system, fertility needs to be excellent, so how do we create room for compromise?
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What can we do to increase the chances of conception rate being higher than 50%, and how do we limit the damage from the inevitable repeats?
We select our best maiden heifers and the elites of the cow herd – those which calved in February, are fifth lactation or below, and are cycling regularly.
Timing is important, as sexed semen is viable for a shorter period (12-16 hours) in the reproductive tract, compared with conventional (24 hours).
Normally, with conventional semen, we serve cows that are in heat after milking in the morning – just once daily.
Timing for sexed semen is 14-20 hours after onset of heat, making that window for service trickier.
In order to tick all the boxes around timing we changed to heat detection collars on cows and heifers last year. The system we use also gives us a record of all pre-breeding heats.
This facilitates bringing additional cows for service into the first week of breeding with a single shot of progesterone.
We can offset any lost days in milk next year by having more calved in week one of February.
Some refer to this as the “why wait?” programme, but for us it is more, “why wait for them to repeat when we can offset the risk earlier?”.
Sexed semen was used for the first five days of breeding, on 20% of the cows and 75% of the heifers. Repeats occurred early in the fourth week of breeding, so we should keep to calving in February.
We hope to generate next year’s replacement heifer calves from the best and get Angus and Hereford calves from everything else.
The phrase “the best laid plans” comes to mind, and June will be very revealing.