Friday, March 29, 2024

Plan for mating success

Avatar photo
Information is power – boosting a dairy herd’s reproductive performance is a perfect illustration of the old cliché.
Reading Time: 3 minutes

Dr Jenny Weston, veterinarian at Massey University and current president of the Dairy Cattle branch of the NZ Veterinary Association, said that accurate heat detection – along with cow body condition score and well-grown young stock entering the herd – is regarded as the biggest barrier to good herd-level reproductive performance.

“The rest is the icing on the cake.”

In heat detection, a little information can go a long way.

Weston said that as well as allowing for more accurate identification of non-cycling cows, recording actual heat dates over the pre-mating period could be used to confirm heats observed during the actual mating period, potentially driving better conception rates.

In general, return rates – days between observed heats – should average about 21 days. However, Weston said there was some variability between cows and a short return between the first and second heats was not unusual.

“It is not uncommon for cows to have very short returns, 10-12 days, after their first heat. They will then settle into something more normal.”

Planning was also critical.

For example, if choosing to treat non-cyclers, getting the artificial insemination (AI) timing right and making sure all parties – veterinarian and AI company – were kept informed could potentially have a major impact on its success.

“There is a reasonable time range, but if you are saying insemination needs to be between ten and 20 hours after the last injection and the AI technician isn’t in the loop and turns up at 19 hours, leaving an hour to get 200 cows inseminated, quite a lot of those are going to be outside that time period.”

Not all cows will respond to non-cycler treatment and Weston said expecting a normal conception rate was unrealistic. Genuine non-cycling cows often have an underlying issue such as poor body condition or other health issue impacting on reproductive performance and that is why conception rate can vary between about 25% and 55%.

Another example would be making sure tasks like checking for uterine infections are planned and scheduled correctly.

“Nearly 100% of cows will have a bacterial infection of the uterus at calving – because that’s life. The vast majority of those cows will clear it themselves. So if you check every cow seven days after she has calved, an awful lot will end up being treated. If you leave them a week or two longer, a lot of them will have cleared it themselves.

“It’s a compromise between being over eager and treating a lot versus leaving it too late so that those who are still infected have been left a long time, and it might have caused some permanent damage.”

Ideally the checks should occur about three weeks post-calving. If doing whole herd checks, Weston recommended testing batches of cows that had calved over a two-week period – animals that would have calved 3-4 weeks earlier.

Routine inductions to end

The culmination of a ten-year process will mean routine calving inductions reduced to zero from June 1, 2015 although there will be a dispensation process available catering for “Acts of God”. For cases of individual animal welfare the treatment is justified and doesn’t require any prior approval.

Dr Jenny Weston, president of the Dairy Cattle branch of the New Zealand Veterinary Association, said that 10 years ago there was a review of the drugs used to induce calving, focusing on their impact on animal welfare and withholding periods.

The four industry bodies involved – the NZ Veterinary Association, Federated Farmers, DairyNZ, and the Dairy Companies Association of NZ – agreed to progressively reduce the proportion of a herd that may be induced as part of routine farming practice, reducing to nil next season.

With the threshold set at 4% this season, all inductions are logged into a website operated by industry-good body, DairyNZ.

Weston said an “Act of God” was something a farmer could not predict or mitigate against. Examples could be a shed destroyed by an earthquake, a theileria outbreak coinciding with mating, or a prolonged technical failure in the artificial insemination process.

“The dispensation process is something where you work with your veterinarian, you put together your evidence of what happened, being able to show a direct effect on herd repro – for example your previous six-week in-calf rate, then despite having followed industry best practice like testing and vaccinating your bulls for BVD, proactive treatment of non-cyclers etc, you’re still left with a disastrous result.”

That application is then forwarded to the farmer’s dairy company for a decision.

Total
0
Shares
People are also reading