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• Treatment of Non-cycling Cows

Treatment of Non-cycling Cows

The veterinary examination and treatment of cows that have not been mated after one round of AI is a common and accepted procedure.  These cows are referred to as No Visible Oestrus or NVO cows.  In the last few years there have been a number of investigations into the most effective timing and treatment of NVO's.  This work has been done in the major dairying regions of Victoria, including our area.  It has been carried out on commercial dairy farms under normal industry conditions.  The results are therefore very applicable to most of our commercial herds.

The National Dairy Herd Fertility project, now called "In Calf" has confirmed and reinforced the fact that later calving cows have substantially reduced fertility compared to their earlier calving herd mates.  It is these later calving cows that make up this bulk of the group of NVO's.  If we do nothing, many of these cows end up empty, or as late cows in the following year.

There is good evidence that early treatment of NVO cows results in:

•  Increased numbers in calf to AI.
•  Less empty cows.
•  Fewer cows to induce in the following year.
  

The timing of treatment appears to be important in getting the maximum benefit.  There are two strategic times that treatment can be targeted.
Prior to Mating Start Date (MSD): This requires heat detection commencing about 30 days before MSD.  An easy way to do this involves use of tail paint with twice weekly recording and topping up.  If a different colour is used on cows that have cycled the NVO's can be readily identified.

After one "round" of AI: This allows all cows to have a chance to be detected on heat say 21-24 days after MSD or earlier in herds that have synchronised.

Treatment of cows prior to MSD will mean that approximately twice as many cows will be examined, however, this gives the true non-cyclers a chance to be mated twice in the first 30 days of mating.  The trial results show that these early treated NVO's have fertility that is almost equal to their non treated naturally cycling herd mates.
The earlier that NVO's are identified, examined and treated, the better.

The standard treatment for true non-cycling or "anoestrus" cows involves the use of a CIDR and an injection of oestrogen.  This results in a very high percentage of anoestrous cows showing heat after CIDR removal.  Trial results have shown that some cows that fail to conceive do not come back on heat.  This problem can be overcome using reinsertion of the used CIDRs (used but cleaned before reuse) and re-treatment with oestrogen.  Re-treatment of anoestrous cows, is a low cost option that is worth considering.

Examining and treating NVO cows is a very worthwhile exercise.  If you have any queries regarding the type of program appropriate for your herd, please contact us.