Dairy Day, 1995; Kansas Agricultural Experiment Station contribution; no. 96-106-S; Report of progress (Kansas Agricultural Experiment Station and Cooperative Extension Service); 742; Radiotelemetry; Pressure sensors; Estrus; Heifers; Heat Detection


In Experiment 1, the effectiveness of two estrus-detection methods (visual observation vs radiotelemetric, pressure-sensitive, rumpmounted devices [HeatWatch®]) were compared in heifers. A pressure sensitive device containing a battery-operated radio transmitter was affixed to the tailhead rump area of each of 41 heifers. Activation of the sensor sent a radiotelemetric signal to a microcomputer via a fixed radio antenna. Heifer identification, date, time of day, and duration of standing events were recorded. Estrus was synchronized, and heifers were observed visually for signs of estrus. Number of standing events during estrus, determined by the radiotelemetric device, averaged 50.1 ± 6.4 per heifer, with the duration of estrus ranging from 2.6 to 26.2 hr (average = 14 ± .8 hr). Number of standing events and duration of estrus were greater, but duration of standing events was similar, for heifers identified in estrus by both methods compared to those identified by the radiotelemetric device alone, indicating that heifers with a limited number of standing events and estrus of shorter duration were missed by visual observation. In Experiment 2, the average number of standing events during estrus was greater when estrus was induced early (days 6 to 9) in the cycle by PGF compared to those 2a induced later (after day 10) in the cycle. Regardless of when injections of PGF2α occurred during the cycle, duration of standing events and duration of estrus were unaffected. Radiotelemetric devices are useful in identifying a greater proportion of heifers in estrus (increased efficiency) compared to visual observation with similar accuracy.; Dairy Day, 1995, Kansas State University, Manhattan, KS, 1995;

Included in

Dairy Science Commons


Rights Statement

In Copyright - Educational Use Permitted.

To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.