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How to improve likelihood of success with sexed semen


Sexed semen provides many potential advantages to dairy farmers. The most obvious and compelling reason to use sexed semen is because of the sex bias induced in the calf crop. Stephen Butler, Teagasc, Moorepark has some advice as part of Teagasc / ICBF Breeding Week.

Why use sexed semen?

Sexed semen provides many potential advantages to dairy farmers. The most obvious and compelling reason to use sexed semen is because of the sex bias induced in the calf crop, with 90% of the pregnancies resulting in a heifer birth, and only 10% male dairy calves. This in turn means that more beef semen can be used, using bulls with high Dairy Beef Index. This will provide long term sustainability for the Irish Dairy Industry.

Some of the key factors that affect the likelihood of pregnancy establishment when using sexed semen have been identified. These are summarized in the text below and discussed in the following clip  

Guidelines for sexed semen usage 

Bull team

  • Pick highest EBI bulls available
  • Use a team of ≥5 bulls

Suitable dams

Heifers 

  • Target live-weight and BCS ≥3.25
  • Cycling regularly

Cows

  • Parity 1 to 4
  • >50 days in milk on day of AI
  • BCS ≥3.00
  • Cycling regularly
  • Free of postpartum disorders and uterine disease

When to use?

  • During the first 3 weeks of the breeding season, and within first 10 days if possible.

Timing of AI

  • 14 to 20 h after heat onset (first standing mount). Practice AM/PM rule if possible. If using once a day AI, use conventional semen if time of AI is <14 h after heat onset.

Fixed time AI

  • Costly, but mitigates risk
  • Facilitates targeted usage of sexed semen on mating start date

Straw handling on day of AI

  • Organise sexed straws into one goblet
  • Thaw 2 sexed semen straws at a time MAX
  • Thaw straws at 35 to 37 °C for 45 seconds
  • Load straws into pre-warmed AI guns, keep warm.
  • Deposit semen in uterine body
  • Complete inseminations within 5 mins

How many sexed semen straws do I need to use?

For farmers that are interested in using sexed semen, the first question often asked is how many straws do I need to use? First, identify the target number of replacement females that you want to have born on the farm. Second, decide if sexed semen will be used on heifers, on cows or on both. In the worked example below, a farmer with a 100 cow herd will use sexed semen on all the maiden heifers and on a targeted subset of high fertility lactating cows. Beef AI or beef stock bulls will be used on all repeats (heifers and cows) and any lactating cows not suitable for sexed semen. It is essential that all the guidelines in Box 1 above are implemented to maximise the chances of success with sexed semen. 

For more information go to Breeding Week