Breeding strategies approaching mating:

Getting the plan right

You put in a lot of effort to get that cow inseminated and in calf – with some planning you can use some simple strategies to achieve your objectives around calving patterns and getting good quality heifer replacements.  

Hormone Intervention

A common intervention strategy used to impact fertility is to synchronise non-cycling cows, but there are some myths out there about how this works and what you can expect from this strategy.

Trials with improved heat detection aids such as Estrotect Heat Detectors demonstrate that more cows than previously thoughts show up in heat before fixed time insemination.  This means that with synchronisation it still pays to monitor those treated animals and identify those cycling early.

Intervention will not reduce empty rates but will get your cows into milk earlier - and more milk equals more profit.  If you are using intervention, you need to get your program started early rather than waiting to identify non-cyclers during the mating period.

Pre-mating heats are essential to ensure the cows that need to be treated can be programmed for fixed time insemination as close to start of mating as possible.

Success or failure of an intervention program will not be measured on empty rates but on the percentage of cows that are pregnant after 6 weeks of mating.  Your need to work with your vet on these programs, but make sure your CRV AmBreed Field Consultant is aware of your plans so you have Estrotect Heat Detectors on hand and your AI Technician is organised ahead of time.

Short Gestation

Cows that have a shorter gestation period will be in calf for less time and in milk for a longer period of time.  It can be a useful strategy to condense calving, particularly if as a result of recent droughts you are finding that your calving pattern is stretching out.

By measuring this trait in bulls we give farmers another tool to compact the calving period, giving cows a longer period of time to recover relative to the ideal mating period window, this increases the chances of the cow getting back in calf to A.I.


As a result of NZAEL’s work on developing a genetic evaluation of Calving Difficulty, they have now established Gestation Length as an official BV.  CRV AmBreed offers a good variety of bulls that are known to have Shorter Gestation Length.

Using Short Gestation Sires is another tool in the mating management toolkit.  Work smart, not hard.  

SiryX – Sexed Semen

Following our launch of SiryX Sexed semen from NZ Proven Bulls three years ago, we are now able to offer a wider range of NZ Proven Bulls.  

SiryX gives you the opportunity, even with a known slight decrease in  conception rates, of providing improved numbers of heifer replacements for your herd due to the 90+% heifer to bull calf ratio.

By assuring female progeny you can target higher genetic merit cows for mating to provide higher quality heifer replacements or create surplus heifers from your herd for the vibrant heifer calf market.