Reproductive Performance

Do you want a tighter calving pattern?
Would you like to reduce the number of late cows?
Want to get more cows in calf earlier to AI next season?

Now is the time to look at how this can be achieved next season. The InCalf study identified 6 important factors that have significant effects on herd reproductive performance in many seasonal calving herds. One of these important factors is :

Calving date to mating start date interval

Calving date to mating start date interval has been found to have a huge effect on fertility. To allow all cows in the herd to have a long calving to mating start date interval it is important to achieve a tight calving pattern.

Why is calving date to mating start date interval so important?
The InCalf study found :
  • Cows that had calved by the 3rd week of calving had the highest fertility.
  • Cows calved in weeks 4-6 of calving had reduced fertility
  • Cows calved after week 6 are quite likely too have poor reproductive performance

What can I do to ensure a long calving to mating start interval?

There are three key areas to focus on to achieve a tight calving pattern, they are :
  1. Heifer Management
    1. Calve as many first calvers as possible in the first 3 weeks of calving.
    2. It is achievable to calve 70% by the first 3 weeks and 95% by 6 weeks
    3. Yearlings must be in good condition and exceed minimum target weights for mating.
    4. Use adequate numbers of highly fertile bulls, (1 bull per 30 yearlings)
  2. Purchase Decisions
    1. Calving dates of any purchased cattle are an important consideration
    2. Ensure cattle being purchase have reliable estimates of dates of conception
    3. Place a higher value on cattle that will calve earlier in your calving period, than cattle that would calve later (after the 1st 3 weeks)
  3. A Planned Approach To Calving Induction
  • How do I plan an induction program?

    Firstly calving dates need to be obtained by pregnancy -testing the herd. This is best done early.  Ideally the herd is pregnancy tested 8-12 weeks after the end of AI followed by a retest of the not in calf cows 6 weeks after mating is completed.  This improves the accuracy of aging of the pregnancy. Anytime after the bulls have been removed for longer than 6 weeks is suitable. Once calving dates have been collated, any cows that will calve after the first 6 weeks of calving can be identified for an induction program.



    These late calving cows can be induced to calve between 8 and 11 weeks before their natural calving date.  For many, this will be within the first 3 weeks of calving. This gives them a much longer calving date to mating start date interval.  Cows will have an improved chance of getting in calf early to AI and maintaining their early calving cycle within the herd.



    Although it is feasible to induce all late calving cows, there is a higher risk of animal health problems inducing cows over 6 years of age.  Studies have also shown that older cows have less ability to make satisfactory gains in their calving time following induction.



    This strategy of identifying late calving cows early in the season and planning an early induction program is one of the most effective tools available to improve reproductive performance in a herd.


For more information about inducing cows click here.

Click here to view the rest of the 2002 February newsletter.