News & Advice

Heat detection fatigue – How long is long enough?

Oct 12, 2020 | Dairy, Dairy Farm Reproduction

Steve Harkness, Veterinarian, Anexa Vets Gordonton

Heat detection is crucial to getting the best possible reproductive outcomes. It is another job at a busy time of the year which requires a lot of effort and planning to get right.

Reasons why heat detection gets harder with each round of AB.

Farm staff get exhausted with continual maintenance of heat detection aids (e.g. touching up tail paint) and physically inspecting cows for bulling activity and then drafting them.

Staff falsely believe that most cows will be pregnant after the first round. The average conception rate to AB in NZ is only just over 50%. This means that under half of the herd on average is pregnant after the first round. There are still plenty of bulling cows to find.

Less cows bulling means smaller sexually active groups and bulling cows are harder to find. Increased temperature and humidity can depress bulling behaviour as we head into summer.

Hotter temperatures can depress bulling behavior as summer kicks in.

Bulls are a pain, should I just do AB for the entire mating?

This is when heat detection fatigue can destroy your repro results. Your team must be prepared for the long haul. Some cows are particularly hard to detect in heat and bulls are more likely to find them.

Before considering this approach assessment of previous heat detection using MINDA analysis etc. may give us clues to your farms heat detection capabilities. Anexa vets will be able to help with this.

Is automated heat detection technology the answer to heat detection fatigue?

Recently there is greater interest in automated systems. These may work by monitoring individual cow activity (ear tags or collars) or camera inspection of heat patches and electronic patches.

Well performing technology can achieve an accuracy similar to an experienced farm manager, but performance varies between and within systems.

Tail paint, or other backup, should be used in case of technology system failure.

These automated systems can be costly and not fault free. If you are interested in this technology, visit a farmer already using it and check their performance and feedback. All the tools we use to assist with heat detection (technology or traditional) are heat detection ‘aids’. No aid is perfect. Therefore, a combination of aids and increasing the time spent interpreting and reading the aids as the number of cows on heat decreases will lead to better results.

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