When to focus breeding on Dairy-Beef

During the early stages of the breeding season, the main focus for many herds is on creating enough suitable replacements that will be joining the dairy herd in two years’ time.

For these animals, performance traits such as milk production, fertility and health are the main drivers when selecting sires and the EBI has become the go-to measure of these traits for most dairy herds. Once we have confidence enough dairy replacements are secured, the sire selection needs to shift to creating calves with a beef focus in mind. For this purpose, the DBI was developed to identify those sires ideally suited for Dairy-Beef breeding.

To make an informed decision as to when the shift in breeding direction needs to take place the following has to be taken into account:

• How many replacement heifers are you aiming to have?
• Based on previous breeding seasons, how does the herd traditionally perform in terms of 21-day Submission Rate, Conception Rate to first serve, 6-week In-Calf Rate and overall Pregnancy Rate?
• Are you planning to use Sexed Semen or only Conventional Semen AI?
• Is AI used for the heifers?

Three weeks into the breeding season is usually a good time to take stock of Submission Rates and identify any animals not yet served. Picking up the cows that show repeat heats over the following 3 weeks is a good indicator for Conception Rates to first serve and thus Pregnancy Rate in the vital first weeks of the breeding season.

Those herds that used sexed semen for the first round of AI will be particularly interested in gauging Conception Rates and decide whether to breed repeat cows with dairy AI sires or switch to beef bulls to improve non-replacement calf value next spring. As a rule of thumb, you will need two sexed semen straws for every replacement heifer you are hoping to obtain. Use these straws on the most fertile and highest EBI animals, usually these are the maiden heifers, first, second and some of the third lactation cows. This also means that lower EBI cows in the herd can be bred to beef AI from the start of the breeding season, increasing the genetic gain of your future dairy herd.

Decide whether to keep breeding with dairy sires to achieve more replacements or swap to beef bulls based on the number of animals served and the number of repeat heats following the first three weeks of breeding.

Three scenarios to use as an example, with conservative fertility indicators (submission rate of 80% in cows, 90% in heifers, 50% conception rate for conventional semen, 45% conception rate for sexed semen and a 9:1 heifer to bull ratio for the sexed semen):

• Herd A uses conventional AI on the 100 cows for three rounds and a beef bull then, A beef bull is used for the 30 heifers from the start. This should approximate to:
  • 32 heifer replacement calves
  • 32 dairy bull calves
  • 50 beef bred calves
• Herd B uses conventional AI on the 100 cows for three rounds and a beef bull then and 1 round of sexed semen on the 30 heifers followed by a beef bull. This should approximate to:
  • 43 heifer replacement calves
  • 33 dairy bull calves
  • 35 beef bred calves
• Herd C uses 1 round of sexed semen on the 30 heifers and half of the 100 cows, conventional semen on the remaining cows for the first round, followed by a beef bull. This should approximate to:
  • 37 heifer replacement calves
  • 13 dairy bull calves
  • 65 beef bred calves

If using stock bulls to complete the breeding season after AI breeding has finished, calculate the number of bulls required based on the estimated empty rate:

Typically, 6 weeks of AI breeding in a 100-cow herd will results in a 50 – 70% pregnancy rate. The remaining 30 – 50 empty cows will need at least two healthy bulls rotated on a weekly basis. If this level of bull power is not available to you, consider AI with beef semen for a few more weeks or until the end of the breeding season.

Even though pregnancy can be predicted accurately using individual cow milk sample testing 3 weeks after breeding, 28 days is often seen as the earliest pregnancy diagnosis can be made with confidence in cattle, using traditional ultrasound scanning. Early pregnancy diagnosis can be very helpful to make further breeding decisions and to identify specific reasons for unsuccessful breeding in empty cows. However, it is only after 60 days that the pregnancy is well established and until that time, natural embryonic loss in up to 15% of pregnancies is acceptable.

First Published 3 May 2024