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23rd February, 2019


The month of July has been one of the wettest on record for farmers on the west coast while further inland the rain in late July was a welcome relief on light soils.  Breeding programmes for spring calvers should now be at an end.  However, stock bulls still run with most dairy herds visited.  Cows bred now will calve in mid-May.

With quotas not a limiting factor to production, many farmers consider milking cows into December or indeed through the winter months.  Milk price will ultimately determine the economics of this option.  However, many farmers consider the culling of young cows in first through third lactation as unacceptable if they fail to establish a pregnancy between April and July.  Therefore we will continue to have May and June calves on many grass-based milk production systems.

The first three weeks of August generally encompasses a wait and see approach in the breeding programme.  Farmers prefer to get a full picture of their breeding programme outcome by waiting for four weeks after the “bull” has been removed to scan the entire herd for pregnancy status.

Remember that the accuracy of foetal gender determination and identification of cows carrying twins decreases as cows extend beyond three and a half months of pregnancy.  The information harvested from this scan forms the basis of your business for 2016.

Scanning your dairy herd will present many surprises to farmers.  Cows presumed empty on the basis of heat activity will be identified as pregnant.  Up to 10pc of pregnant cows will present with signs of heat, unfortunately, many of these pregnant cows end up needlessly in the abattoir.

Scanning will also identify cows as empty which were presumed pregnant.  Some of these cows cannot present signs of heat because of either a hormonal dysfunction or an embryonic foetal death maintaining a pregnancy state.

The primary occurrence of embryonic foetal death in scans at this time of year is associated with cows carrying twins.  Your cows’ reproductive tract consists of two uterine horns.  The presence of twins in one uterine horn results in at least a fire-fold increase in the risk of embryo/foetal death.  These cows will not present a return to normal heat cycles for periods up to 3 months after embryo/foetal death.

Having identified empty cows, farmers have to make decisions on the future of these cows.  In strict grass based systems, these cows will be culled at the end of the grazing season.  Housing capacity maybe a premium or it may be considered uneconomic to fatten these cows prior to culling.

Alternatively, farmers will use the scan to identify “fit” empty cows, which do not present with reproductive abnormalities, have low somatic cell count, good locomotion scores and are less than their fifth lactation for recycling into an autumn calving programme or introduction into the 2016 spring breeding programme.

Bearing in mind the importance of nutrition and management for transition outcomes for the dairy herd, it is essential to generate accurate calving dates.  Scanning prior to three and a half months of pregnancy will provide you with this essential information.  Stock bulls are used on the majority of dairy farms after an initial 4 to 7 week AI breeding programme.  In our experience, less than 10pc of services associated with pregnancy from a stock bull are recorded.

Transition management accounts for approximately 80pc of herd health and reproductive outcomes in the dairy herd.  It is therefore imperative that we have accurate calving dates to ensure that cows experience an optimal nutritional and management regimen for the six week period precalving and two week post calving describing the transition period.

Farmers lament when you identify cows carrying twins.  The complications associated with management of these cows are immense.  The increased risk of metabolic diseases, retained afterbirth, poor reproductive survival post calving and poor survival rates among calves born.  The incidence of twins born ranges between 2 and 10pc on farms.  The incidence increases with age of the cow and genetic potential for milk production.  The reported incidence is lower than that experienced because farmers do not wish to have inspections from the Department of Agriculture associated with questioned incidence of twin births.

This latter problem could be rectified if scan data could be used as supporting evidence to the Department of Agriculture.  Finally, there is a need for proactive preventative health management at this time of year.  Farm visits reveal that body condition scores are below target for many cows, when cows should be increasing BCS.  This status is primarily associated with IBR, Lungworm, Stomach fluke or Liver fluke infections. It is essential that you establish your current status using a combination of blood, milk or dung samples.  This is very cost effective in planning for the future transition period.

Dr. Dan Ryan is a bovine reproductive physiologist and can be contacted at

Article written by Dr. Dan Ryan for the Farming Independent 11th of August 2015