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Non-cycling cows

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:

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    reducing submission and conception rates

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    delivering fewer days in milk the following year than their cycling herd mates

 

Cycling targets

75% - 10-days prior to mating start date:

Cycling targets: 75% - 10-days prior to mating start date

 

 

 

85% - mating start date:

Cycling targets - 85% mating start date

 

 

 

90% - in the first 3 weeks of mating:

 Cycling targets: 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:

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    young, first and second calvers - especially if poorly grown

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    thin cows

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    late calvers

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    health issues

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    breed (Friesians are more susceptible)

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.

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.

Cost:

Risk of low submission rate and poor reproductive outcomes with few options for addressing these.

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.

Cost:

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    time and effort

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    rotational planning

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    extra electric fencing

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    setting up breaks etc.

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.

Cost:

  •  

    Multi-herd farms could achieve a reduction in labour, time and effort

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    Estimated cost of approximately $46 cost in lost milk yield for each 28 days on OAD. 

*The figures above are based on a:

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    daily milk yield of 1.6 kg milk solids/ cow

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    $5.50/kg MS pay out

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    19% drop in production over the period

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.

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

Advantage:

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    generates earlier AI calves

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    returns come in at the start of the second round

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    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.  

Selective treatment

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.

Cost:

  •  

    cost of treatments and vet/advisory work

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    reviewing  and planning

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    time and labour for drafting cows etc.                                                                                                                                                                

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.

Cost:

  •  

    cost of feed

  •  

    inconsistent effect on reproduction

  •  

    cost of advisory input, labour and time

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:

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    Grow your heifers to achieve liveweight and body condition targets at 22 months. Learn about growing heifers well

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    Manage 2 & 3 year old cows in the herd carefully

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    Calve cows at BCS target ( NZ BCS 5.0 for 4+ years and 5.5 for 2 & 3 year olds). Convert NZ BCS to Ireland BCS

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    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)

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    Manage to minimise health issues

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    Reduce the percentage of late calvers in your herd

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    Keep BCS loss to under 1 BCS unit between calving and mating

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    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.