Doctoral Dissertations

Date of Award


Degree Type


Degree Name

Doctor of Philosophy


Animal Science

Major Professor

Kelly R. Robbins

Committee Members

Benny Bell, James K. Miller, Stephen P. Oliver, Fred Hopkins


Two studies investigating managerial effects on cattle behavior and physiology were performed. In the first study, forty mid-lactation Holstein cows were divided into two groups and housed in identical, light-controlled, stanchion barns. During the 3 wk pretreatment period, incandescent lights (providing 100 Ix 1 m above the floor) were on from 0300 to 2100 h in both barns. Treatments consisted of lights on from 0300 to 2100 h in one barn and lights on from 0700 to 1700 h with a skeletal light period between 0400 and 0500 h in the other for 14 wk. Milk yield; body weight; serum prolactin, cortisol, and triiodothyronine concentrations; and duration and frequency of eating and lying down and frequency of drinks were not significantly different between the two treatments. Results suggest savings in utility costs could be attained by using a skeletal light period to replace a long continuous light period without decreasing milk production or eating time.

To detect trends in behavioral feeding preference, 48 lactating cows were observed 72 continuous h during five different feed management regimes. Treatments were: hay and silage fed simultaneously at 0830, 1300, and 1630 h; hay fed at 0730, 1145, and 1530 h and silage fed at 0830, 1300, and 1630 h; silage fed at 0730, 1145, 1530 h and hay fed at 0830, 1300, and 1630 h; hay and silage fed simultaneously at 0700, 1000, 1300, and 1600 h; and hay and silage fed simultaneously at 0700 and 1630 h. Binomial z-scores indicated that cows had definite eating patterns which went across all treatments. Strongest feeding preferences were to eat grain, then silage, drink water, and then eat hay. However, behavioral differences between treatments were not detected. On average, cows ate silage 9.51 times/d, 18.45 min each time; hay 5.59 times/d, 10.91 min each time; grain 7.33 times/d; and drank water 4.68 times daily.

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