Traditional heat detection methods relied on visual observation of heat-related behavior displayed by the cows utilizing an AM-PM viewing schedule – the cows are observed for a half hour twice a day, once in the morning and once in the evening.
The average accuracy of visual observation is around 40% due to the fact that visual heat detection requires expertise, short heats are prevalent and may fall between observations, most of the heats occur between midnight and 6 am when there is no one to see them among other reasons.
The inefficiency of visual observation led to the assimilation of several types of solutions to the issue of heat detection. These heat detection aids can generally be divided into three categories: mounting sensors which provide an indication of the cow in heat getting mounted by another cow, hormone synchronization protocols which time the cows' heat cycles and electronic heat detection aids.
Tail painting and mount sensors provide an indication to the farmer if the cow has been mounted by Heat Detection Cows (a typical heat-related behavior) and therefore is in heat. These methods do not provide a marked improvement in heat detection accuracy as they are affected by cow activities unrelated to heat, nor are they able to determine the exact timing of the beginning of the heat cycle to optimize insemination timing and require a considerable investment in labor to administer, maintain and monitor them.
Electronic heat detection aids were first introduced into the market in the 1980s with the deployment of pedometers. Pedometers are strapped to the cow's leg and count the number of steps she takes – an increase in the number of steps taken by the cow provides a 70%-80% accurate indication of the cow being in heat.
Pedometers were never able to generate considerable market penetration due to their cost-benefit ratio. 70% accuracy was not enough to induce farmers to invest in these systems.