Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/1/1996
Publication Date: N/A
Technical Abstract: Self-locking mangers are commonly used to restrain cattle for various management tasks such as artificial insemination, pregnancy checking, and monitoring herd health. Some abuse of the system may occur if cows are allowed to remain in the headlocks beyond the management routine. Two trials were conducted, first in the spring (April and May 1994) and a second in the summer (July and August 1995) with lactating Holstein cows housed in an open free stall unit with self locking stanchions at the feed manger. One objective of the study was to determine whether cows would react to stress of extended lock-up (four h daily) by an increase in serum cortisol. A second objective was to determine whether extended lock-up was more stressful in the summer heat than during cooler spring lock-ups. Fifty-two cows were in the first and 62 in the second trial. The first and third wk were non-lock-up; the second and fourth extended lock-up wks for each trial. During trial 1, cows were locked up at the feed manger from 7:00 AM to 11:00 AM. Trial 2 cows were in extended lock-up from 9:00 AM to 1:00 PM daily. Cortisol increased during lockup an average of 5.3+/.9 ng/ml during the spring trial and 9.1+/1.1 ng/ml during the summer trial. Corresponding cortisol means were 9.4+/.9 vs 13.8+/1.1 ng/ml during non-lockup in spring vs. summer and 14.7+/.9 vs 22.9+/.9 ng/ml following lock-up in spring vs. summer (P<.0001). Ambient temperature averaged 12.3 deg C and 21.4 deg C during the spring and summer trials respectively, while corresponding relative humidity averaged 45.2 and 35.6%. Extended lock-up was more stressful, as measured by cortisol increase, during hot summer days than during cooler spring weather.