Good mating results are built on preparation, accurate heat detection, and a healthy bull team.
A few practical checks now can protect submission and conception rates—and help avoid unpleasant surprises at pregnancy testing.
Use more than one heat-detection signal
Tail paint and scratch-off heat patches each have strengths, but no method is perfect. DairyNZ recommends combining aids with observation. Apply tail paint cleanly in a strip no more than 20 cm long and 5–6 cm wide, check it at every milking, and touch it up at least weekly. A patch provides a useful second signal, especially where several staff share heat-detection duties.
Standing to be mounted is the most reliable behavioural sign. Also watch for mounting activity, restlessness, mucus, rubbed paint or an activated patch. Confirm cow identity before drafting or inseminating and record heats promptly. Clear roles and readable ear tags reduce missed and “invented” heats.
Match bull power to the job
Bull requirements depend on the number of cows still expected to cycle, not simply herd size. Allow about one bull per 30 cows requiring service, keep at least two active bulls with any mob, and maintain a second team for rest and replacements. For yearling heifers, use one bull per 15–20 heifers.
Return heats after synchrony create a concentrated workload. Around the expected return window, plan approximately one rested bull per 10 non-pregnant cows, or arrange a short return visit from the AB technician.
Arrange a breeding-soundness examination four to six weeks before use so there is time to source replacements. Confirm BVD status and vaccination, leptospirosis vaccination, disease risk, body condition, feet, legs and reproductive soundness. Quarantine incoming bulls and introduce established teams early to reduce fighting.
Review progress while there is still time to act
From about week four of AB, review submission rate, non-return rate and return intervals with your vet. A high non-return rate can reflect missed returns or phantom cows, while a low result may flag heat-detection, health, nutrition or insemination issues. Early pregnancy testing, extra heat-detection support, targeted treatment or altered bull numbers may still improve the outcome.
This week’s checklist: confirm heat-detection responsibilities; check supplies and records; finalise bull teams and spares; get your bulls tested; and tell your AB technician about synchrony returns or any large, planned AI jobs.
