The autumn of 2013 has been excellent for dairy farming in terms of grazing conditions and milk price.  Current milk price has persuaded many farmers to extend the normal lactation.  There is insufficient regard for body condition score and the requirement for an eight week dry period for mature cows and ten weeks for first lactation cows.  The danger here is that the health and milk production potential will be impaired in 2014.

As spring calving cows near the end of their lactations and farmers get a break from the milking parlour routines, breeding programmes for autumn calving begin.  There has been a steady exodus of participants from this enterprise in the past ten years.  The differential in milk price between liquid and manufacturing does not justify the extra costs associated with winter milk production.

However, there are farmers with constraints imposed by land base, farm fragmentation, supply of skilled labour, cash flow and spread of workload during the year.  There is also the primary risk associated with the genetic potential for milk production in cows used for winter milk production.  These cows are primarily high input of concentrates with high output of milk, which has been associated with a higher incidence of health problems and impaired reproductive performance.  Genetic selection has enabled the production of a more robust cow.  However, nutritional and housing management practices are the primary drivers of health and fertility outcomes.

Breeding programmes for autumn calving will begin now on most farms.

The primary focus has to be healthy cows after the transition period to deliver on both genetic potential for milk production and reproductive performance.  The impact of transition management is best described by a study completed this year by Reprodoc.  Approximately 1,000 cows were scanned 14 to 22 days post calving as part of routine reproductive management.  The cows were classified as healthy (65pc) or unhealthy (35pc) on the basis of a scan of the reproductive tract.  Based on the six month period post calving, 37pc of the “unhealthy” group versus 21pc of the “healthy” group failed to become pregnant.

Therefore, transition management of your cows this autumn will affect the percentage of cows in calf at the end of the breeding period.  It is essential to identify those cows with “unhealthy” reproductive tracts.  This will enable both veterinary attention and potential causes such as subclinical Ketosis and milk fever which can be prevented for future cows in the transition period.

The second objective in the breeding programme is to detect heat in those cows fit for breeding.  Ninety percent of your cows should be cycling when greater than 40 days calved.  The aim has to be a 90pc heat detection rate in those cows fit for breeding.

Farmers are reluctant to use tail-paint as an aid to heat detection indoors.

Scratch cards and Kamar devices have been used as aids with variable degrees of success.  Research using the neck mounted MooMonitor developed by Dairymaster has revealed a heat detection rate of 85pc among cows fit for breeding.  It is noteworthy that missed heats cost in excess of €200.

Preliminary results of trials using sexed semen this year in spring calving herds have according to ICBF been acceptable to encourage commercial uptake.  It is essential that your herd is “fit” for breeding before any consideration is given to the use of sexed semen.  Any setbacks in transition management or the first eight weeks post calving will have an exaggerated negative impact on pregnancy rates using sexed semen.

There has been a significant uptake in use of sexed semen in winter milk production herds in Northern Ireland.  From our records, the average pregnancy rate in maiden heifers is close to 50pc with in excess of 95pc female pregnancies based on foetal sexing from scanning.  We have also advised the use of sexed semen in first and second lactation cows where scans of the reproductive tract in the freshly calved cow and immediately prior to breeding were “healthy”.  The pregnancy rate achieved was comparable with the use of conventional semen.

In conclusion, transition management has already impacted on reproductive potential of your dairy herd.  Accurate heat detection is essential and aids which are proven to work should be considered.  Sexed semen is an option but would advise a health check using scanning beforehand.

Dr. Dan Ryan is a cow fertility expert and can be contacted at www.cowsDNA.com

Article written by Dr. Dan Ryan in The Farming Independent November 5th 2013.

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