Ž .
Animal Reproduction Science 60–61 2000 713–723 www.elsevier.comrlocateranireprosci
Automated electronic systems for the detection of oestrus and timing of AI in cattle
R.L. Nebel , M.G. Dransfield, S.M. Jobst, J.H. Bame
Department of Dairy Science, Virginia Polytechnic Institute and State UniÕersity, Blacksburg, VA 24061-0315, USA
Abstract
Ž .
For the majority of dairy herds where artificial insemination AI is practiced, the limiting factor toward obtaining efficient reproductive performance is the failure to detect oestrus in a
timely and accurate manner. Periodic visual observation has been the dominant method used to identify cows in oestrus. New approaches are being developed to provide automated systems of
detection of oestrus using electronic technology. The goal of an oestrus detection program should be to identify oestrus positively and accurately in all cycling animals and consequently to identify
animals not cycling. The ultimate goal should be to predict the time of ovulation, thus allowing for insemination that will maximize the opportunity for conception. Unfortunately, most studies
designed to evaluate the optimal time of AI generally contained two technical deficiencies: inadequate numbers of cows for valid statistical comparisons and inaccurate knowledge of the
onset of oestrus because of low frequency of visual observations andror efficiency of methods used for the detection of oestrus. Studies using pedometry and a pressure sensing radiotelemetric
system will be reviewed as each have independently obtained an optimal time of AI of 5 to 17 h after either the increase in locomotive activity or following the first standing event associated with
the onset of oestrus. q 2000 Elsevier Science B.V. All rights reserved.
Keywords: Oestrus; Artificial insemination; Pedometry; Radiotelemetry; Bovine
1. Introduction
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Artificial insemination AI was one of the first and most influential biotechnologies of animal agriculture. The benefits of AI have ranged from reducing disease transmis-
Corresponding author. Tel.: q1-540-231-4432; fax: q1-540-231-5014. Ž
. E-mail address: rnebelvt.edu R.L. Nebel .
0378-4320r00r - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž
. PII: S 0 3 7 8 - 4 3 2 0 0 0 0 0 0 9 0 - 7
sion, thus increasing health and longevity to increasing yield traits afforded by genetic selection. Oestrus detection is often cited as the most costly component of an AI
program. An estimated annual loss of US300 million to the USA dairy industry Ž
occurs because of the failure to detect oestrus or the misdiagnosis of oestrus Senger, .
1994 . The efficient and accurate detection of oestrus and the timing of resulting AI remain major challenges to improving reproductive and economic efficiencies of many
Ž dairy farms Foote, 1974; Gwazdauskas et al., 1986; Heersche and Nebel, 1994; Senger,
. 1994 .
Methods of oestrus detection used in investigating time of ovulation have varied. Ž
Some investigators have used frequent visual observation DeSilva et al., 1981; Larsson, .
Ž 1987 , frequent exposure to teaser animals or other cows Brewster and Cole, 1941;
. Nalbandov and Casida, 1942; Mattoni et al., 1988 , or a combination of frequent visual
Ž .
observation with oestrus detection aids Rajamahendran et al., 1989 . Physical verifica- tion of ovulation in most studies has been by palpation of the ovaries per rectum at
Ž frequent intervals Brewster and Cole, 1941; Nalbandov and Casida, 1942; Trimberger,
. Ž
1948; Mattoni et al., 1988 or by frequent ultrasonography Larsson, 1987; Rajamahen- .
Ž dran et al., 1989 . Ovulation has been timed from the cessation of oestrus Brewster and
. Cole, 1941; Nalbandov and Casida, 1942; Trimberger, 1948 and from onset of oestrus
Ž .
Larsson, 1987; Mattoni et al., 1988; Rajamahendran et al., 1989 . In general, these studies did not contain either an adequate number of observations or continuous
observation for behavioral oestrus to accurately determine the relationship of behavioral oestrus and occurrence of ovulation to determine the optimal time of AI.
Traditionally, AI has followed the a.m.–p.m. guideline established in 1948, which recommended that cows observed in oestrus in the a.m. should be submitted for AI in
the p.m., and cows observed in oestrus during the p.m. should be submitted for AI the Ž
. following a.m. Trimberger, 1948 . Although ovulation time was reported from the end
of oestrus, it was noted that initiation of oestrus was important for AI. Timing of AI from the onset of oestrus is important and quite evident when reviewing results of recent
Ž research using electronic methods that determine the onset of standing oestrus Maatje et
. al., 1997; Dransfield et al., 1998 .
There are many physiological, behavioral, and hormonal changes that take place Ž
. during the oestrous cycle of the heifer or cow Allrich, 1994 , but many of these changes
are highly variable among animals and are impractical to measure routinely. This manuscript will emphasize several manifestations of oestrus, which can be measured and
have been correlated with ovulation and succeeding conception.
2. Pedometry
