Cows are considered to be a non-cycler if they have not had an observed heat before mating starts. Non-cyclers reduce herd reproductive performance and farm profitability by:
75% - 10-days prior to mating start date:
85% - mating start date:
90% - in the first 3 weeks of mating:
Two types of cycling cows
1. Non-cycling (sometimes 'slient' cycling) - true non-cyclers
In most herds, the types of cows that become non-cyclers tend to be the same from year to year.
Risk factors for non-cycling in cows are:
If you can identify non-cyclers earlier you’ll have more options, each with costs and benefits.
See DairyNZ InCalf ™ book page 147
How to identify potential non-cyclers
1. Use your herd records to identify the current cows likely to be non-cyclers
2. Decide which cows to intervene with and which option you will use. Focus on your young, high genetic merit and/ or high producing cows
3. Assess the historic success of various options in your herd using your herd reproductive reports
4. Monitor pre-mating heats (Use tail paint/ heat detection aids and herd records)
Your rural advisors can help you with this.
Options for non-cycling cows
There are various options available to you, depending on how far away mating is and how big the problem is. If you wait until close to mating start, it will be too late to intervene other than by hormonal treatment.
- Do nothing
Success is only likely in herds that meet pre-mating cycling targets of 75% ten days out from mating or 85% at Mating Start date.
You may have a subset of cows you wish to use this option on.
Risk of low submission rate and poor reproductive outcomes with few options for addressing these.
- Run them in a separate mob
This may take the pressure off vulnerable cows. Do it at least 4 weeks before mating to get real benefit.
Scientific evidence around the benefit of doing this is not yet available.
time and effort
extra electric fencing
setting up breaks etc.
- OAD (once-a-day) milking
Do this 4-6 weeks out from Mating Start and run them in a separate group to achieve any real benefit.
In a study by Rhodes et al, 1998, OAD milking while cows remained in the main herd, delivered minimal benefit. There was a 19% milk production drop.
This should be considered when looking at OAD options.
Multi-herd farms could achieve a reduction in labour, time and effort
Estimated cost of approximately $46 cost in lost milk yield for each 28 days on OAD.
*The figures above are based on a:
This disregards any longer term impact and assumes cow returns to twice a day milking once mated.
Note: when milking cows OAD, consider if you still need to bring them through the parlour TAD to access their ration.
- Hormonal intervention
This is the only effective option left once you are close to mating.
Using hormonal intervention earlier is generally more profitable than later. Talk the options over with your vet.
Early non-cycler treatments
generates earlier AI calves
returns come in at the start of the second round
reduces bull power demand in the third round of mating when compared to delaying treatment to 3 weeks into mating
Disadvantage: More animals generally require treatment, which can present cash flow challenges.
Decide on the number to treat and pick your candidates early.
Often the cows that end up being treated after 3 weeks of mating are easy to predict. Identifying and treating them early helps to contain costs while maximising the benefits of early hormonal intervention.
Your vet can do a cost-benefit analysis and advise on this option in your herd.
- Preferential feeding
Evidence from New Zealand research in pasture-based systems shows increased feeding during lactation does not necessarily improve fertility (McDougall et al. 1995, Burke and Roche 2007, McDougall et al. 2015).
While increasing feed is likely to be beneficial to cows under feed stress, research results show that in herds with adequate nutrition the production benefits are likely to be stronger than reproductive.
Reducing stocking rate may be more attractive than buying in feed for some farmers or situations, so review your options carefully with your rural professionals.
- Teaser Bulls
While teaser bulls (vasectomised) are generally good heat detectors, there is currently no scientifically robust evidence that they stimulate cycling in non-cycling dairy cows.
Teaser bulls are costly and not recognised as effective for dealing with true non-cycling cows, but may help you with heat detection. This could prove particularly helpful in smaller herds, or later in the mating period, when very few cows are cycling on any given day.
Long term prevention:
If you consistently have more than 15% of your herd as true non-cyclers, there are underlying issues that should be addressed. Prevention strategies involve minimising the risk factors as listed earlier.
The following suggestions may help with addressing these:
Grow your heifers to achieve liveweight and body condition targets at 22 months. Learn about growing heifers well
Manage 2 & 3 year old cows in the herd carefully
Calve cows at BCS target ( NZ BCS 5.0 for 4+ years and 5.5 for 2 & 3 year olds).
Dry cows off on BCS , calving date and feed supply to ensure targets for BCS and feed on hand at calving are met ( 2 & 3 year olds BCS 5.5, 4+ years old BCS 5.0)
Manage to minimise health issues
Reduce the percentage of late calvers in your herd
Keep BCS loss to under 1 BCS unit between calving and mating
Cows are BCS 4.0 – 4.5 at mating
Assess the likely size of the problem in your herd and the various options available to you.
Talk to your advisor about which option or combination of options could work best for you.