Oestrus or ‘heat’ is a period during the female reproductive cycle which signals the animal is sexually receptive. There are many factors affecting the stock keeper capturing this moment and if the usual behavioural and physiological signs are not obvious to the farmer, especially in a larger herd; this critical period may pass unnoticed.

In cattle, the oestrus cycle lasts between 18-24 days meaning that the cow should shows signs of heat every 3 weeks. The duration of oestrus varies between 1-24 hours and recent figures propose that, on average, it lasts up to a mere 8 hours (taking into account any variations in breeds). With this short window of observation in mind, effective heat detection is therefore a critical component of good, reproductive management in any herd.

A high pregnancy rate is the best indicator of a successful AI programme with poor heat detection being the single most limiting factor in most AI programmes. Pregnancy rates, however, are determined by a combination of accurate heat detection, inseminator efficiency, female fertility and semen fertility, with heat detection being at the forefront. After all as Tom Geary, a researcher with USDA's Agricultural Research Service reports, “the most fertile semen and best inseminator in the world cannot overcome the problem of inseminating at the wrong time”.

In any cattle herd whether beef or dairy, there are several different objectives of oestrus management but a reduction of labour costs and increased efficiency is pivotal to farmers of both systems.  It is therefore crucial to attain an accurate degree of timing as efficiency in this area can be critical to a profitable business.  In fact data from a recent study at SAC suggested that improving oestrus detection rate from 50% to 75% would save on average £15,000 / year in a 100 cow herd.

The window for heat observation is short and is not one which the farmer, vet, breeder or stock keeper can afford to miss. Armed with the correct combination of knowledge, experience and tools (such as the Draminski oestrous detector) they can focus on reaching for the holy grail of minimising cost and maximising output.

References:

Ministry of Agriculture, Fisheries and Food, (1984). Dairy Herd Fertility.
NADIS online (2004)
Scottish Agricultural College; (2004)
B J van der Merwe; Cedara Agricultural Development Institute (2011) ‘Oestrus Detection’
USDA Agricultural Research Service