Mating is just around the corner for our Autumn calving herds

Mating is just around the corner for our Autumn calving herds
Dave Curnow, Veterinarian, Anexa Vets Ngatea

For those farms running split or sole Autumn calving systems mating is just around the corner.

Getting cows in calf during winter has its challenges and the mating strategies used can vary depending on farming system. The most striking examples of this would be whether you are full autumn or split calving and what level of infrastructure you have to support the increased supplemental feeding required to support winter milking.
In terms of maximising in – calf rates over May / June, the following are key decision areas to focus on.

1) Mating length – individual farm decision but ultimately the aim is to have the maximum number of cows at peak milk over the entire winter premium payment period.
2) AB or natural mating?


  • Heat detection is potentially harder in winter (shorter days, bad weather / more time stood off, smaller numbers of cows to form sexually active groups).
  • Monitoring submission rates and considering options to improve submission rate include: use of more heat detection aids, potentially using a synchrony program to condense the AB period.
  • If wishing to utilise synchrony ( either CIDR or perhaps prostaglandin why wait) then this needs to be planned with your vet well before mating starts to get the most benefit.

Natural mating

  • Often used (especially with white face beef bulls to maximise calf value).
  • Can be a very practical option for a lot of farms but does have its challenges
2 year old bulls would be ideal but most bulls are likely to be older at this time of year.
Wet conditions can make lameness an issue.
Feed levels may dictate bulls are on an unfamiliar diet over the mating period.
Ensure you have sufficient bull power ( 1 bull per 30 cows +1 running with the autumn herd + a resting bull mob) and that staff are vigilant in monitoring bull performance on a daily basis. Have a think about what your options would be if you do run into bull performance issues.


  • Metrichecking. Can be done from 2 weeks post calving. There is a positive economic return on this for the vast majority of farms.
  • Synchrony for AB systems - CIDR or prostaglandin based programs. These programs can be useful in certain Autumn systems. Discuss these with your vet as correct timing maximises the return on investment.

Feeding over mating

Each farm is different but more emphasis on supplement is generally the case for winter mating ( as opposed to spring ).
Despite this, the same principles apply as for Spring calving herds.
  • Meet target BCS at calving ( 5.0 for mature cows, 5.5 for 2 and 3-year-olds) with no more than 1 BCS loss between calving and mating.
  • Monitor milk protein on the bulk tank to ensure this is steady or ideally climbing over mating. A higher milk protein test is associated with better energy balance and is generally correlated with improved repro performance.

Over periods of adverse weather or where herd BCS is considered suboptimal then strategies to increase the energy density of the diet may need to be considered.
If you have autumn calving cows and would like some advice specific to your farm, contact your local Anexa vet clinic.

Anexa offers an initial free “repro ready for mating” discussion to all dairy members which can be extended to further advisory services if requested.

Date Added: Thursday, 29th April 2021