novel approaches to expression and detection of oestrus in dairy cows

ates. However, because standing heat is only displayed in a limited
number of cows, detection of real-time mounting behaviour is also useful.
Ovulation can still be predicted by mounting, occurring 28.7 hours post
onset of mounting (Roelofs et al., 2005). This is particularly advantageous
especially when only one cow is in oestrus. Here UWB is advantageous
because mounting is displayed in 90% of periods of oestrus (Roelofs et al.,
2005).
The oestrus data recorded by UWB should be beneficial for increasing
conception rates because of the real-time perspective of mounting and
standing to be mounted in relation to optimal timing of AI; 4 to 12 hours
after the onset of standing activity (Dransfield et al., 1998). Other realtime
advantages of UWB have also been proven because the end of oestrus
can be determined, which can also provide an indication for optimal timing
of AI (see Figure 1.2). UWB has the capability to notify the herdsmen when
cows are in oestrus, which allows for visual observation and confirmation
and further action that needs to be taken such as submitting the cow for AI
if she is eligible.
Further novel aspects of using UWB for oestrous detection are that because
both mounting and standing to be mounted can be identified the accuracy
at detecting oestrus increases. When monitoring standing heat alone by
visual observation heat detection rates of only 12%-30% have been
reported (Van Eerdenburg et al., 1996;Roelofs et al., 2005), but when
increasing behaviour monitoring to also include mounting behaviour the
detection rate has been reported to increase to 61% (Roelofs et al., 2005).
Furthermore, when including all behavioural aspects of oestrus as
described by Van Eerdenburg et al., (1996) the detection rate has been
reported to increase significantly to between 74%-90% (Van Eerdenburg et
al., 1996;Roelofs et al., 2005), highlighting future potential for UWB as 3D
positioning has many possibilities for monitoring cow interactions.
Oestrus detected by UWB was confirmed principally by visual observation.
Due to the experimental design of this study continuous visual observation
was used to confirm oestrus accurately. In a more practical situation this
would not be possible because it would be too time consuming. Visual and
CCTV records confirmed the results reported by UWB; 9 cows were seen
mounting and standing to be mounted, and 6 cows did not engage in
oestrous behaviour. There was however one exception when a pregnant
cow (Cow 38) made two attempts to mount another cow probably because
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