Wednesday, April 24, 2024

Fixed-time AI programmes

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Getting access to top genetics without having to outlay large sums of money on expensive bulls is one objective that can be achieved in adopting a fixed-time artificial insemination (AI) programme.
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This was suggested by veterinarian and cattle stud breeder Dave Warburton.

Warburton, who works for the Hunterville Veterinary Club and also farms a small number of stud cows, was addressing a beef genetics workshop in Feilding held in conjunction with Beef + Lamb New Zealand’s AgInnovation event.

He suggested that compared with AI programmes that require daily heat detection of the females, fixed-time AI programmes require: 

  • Minimal or no heat detection
  • Only three or four yardings of the AI mob
  • Less time spent with the females at what is traditionally a busy time of the year. 

Not only are the results achieved satisfactory but the programme results in a condensed calving and if more heifers than needed as replacements are mated, no bull is required for tailing up. 

Results:

Average in-calf results for mixed-age cows are around 65% and for heifers around 60%, but Warburton’s results in his herd are in the 90+ % region for both age groups.

“For top results you must pay a lot of attention to detail,” he said.

“Choose your programme carefully in conjunction with your vet and AI technician.

“Be accurate and competent with the hormonal injections, paying particular attention to dose and accuracy of placement and ensure the semen is sound. (All bulls and all batches should have one sample straw assessed after thawing).” 

Females should:

  • Be subject to no or minimal stress
  • Be given abundant, high-quality feed with plenty of fresh clean water
  • Not be subjected to a sudden change in diet from three weeks before to three weeks following insemination
  • Be on a rising plane of nutrition
  • Be cycling before the start of the programme for good results
  • Have good levels of minerals
  • Not be trucked from days four to 45 after being inseminated. 

Warburton said heifers could respond to the programme over a wider time frame, so some heat detection and AI might be beneficial for those in season earlier than the time AI was scheduled.

He outlined three programmes for heifers and two for cows because the timing of hormone injections, CIDR duration and time of AI is different for the two age groups. The window for performing AI represents average mob times for the different programmes, but Warburton stressed that the females in a mob that showed standing heat first should be the first to be inseminated.

“Not all females will display a standing heat, however they should still be inseminated regardless.”

One of the few downsides of these programmes may be that females that do not conceive to the first insemination, miss a cycle and often conceive to a tail-up bull in the third cycle. 

Summary:

Fixed-time AI programmes compared with traditional heat detection programmes:

  • Require less time
  • Result in a more compact calving
  • Achieve satisfactory results
  • Need close attention to detail to achieve the above
  • Require females to be managed carefully for a period of at least three weeks before being AI-ed to three weeks after.

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