Comparison of serum steroidal hormone concentrations in buller steers, riders, and uninterested penmates Investigation of sickness, body weight, feed bunk status, and implant condition during buller occurrence

Abstract

Liveweight; rectal temperature (on days one and 3); implant condition; feed bunk condition; and serum hormone concentrations of trenbolone, trenbolone acetate, testosterone, progesterone, and estradiol 17? (on days one and 3) were measured in rider steers (n=17), buller steers (n=6) and control steers (n=18) at the time of bulling activity. Day one was considered the day of initial bulling activity. Liveweight at the time of bulling did not differ between groups (p=0.99), nor did rectal temperature at the time of bulling or the rectal temperature on day 3 post-bulling (p=0.93, p=0.80). There was a significant relationship between liveweight at the time of bulling activity and day one rectal temperature (p=0.002); however, the relationship between liveweight at the time of bulling and day 3 rectal temperature was not significant (p=0.31). The condition of growth hormone implants at the time of bulling did not differ between groups (p=0.27). Day one serum estradiol 17? concentration was significantly different between groups (p=0.05). The four steers that had detected (and quantified) levels of estradiol 17? on day one were riders; on the other hand, one buller and one control steer had detected (not quantified) levels of estradiol 17? on day one. The available data suggest that rider steers may have elevated levels of estradiol 17? as compared to bullers and non-involved penmates at the time of bulling activity. Furthermore, the results of this study suggest that the rider steer should be scrutinized as closely as the buller steer in future studies.