The objective of this study was to determine if cattle that were famil
iar with white locoweed (Oxytropis sericea Nutt, ex T&G) could be aver
sively conditioned to avoid eating it, In the first preliminary trial,
we tried to aversely condition native steers that were already eating
locoweed Six of 12 steers were penned, fed fresh-picked locoweed, the
n dosed via a stomach tube with lithium chloride (LiCl, 200mg/kg BW),
When released into the locoweed-infested pasture, they gradually incre
ased locoweed consumption over the next 5 days, The conditioning proce
dure was repeated with a lower dose (100 mg/kg BW), but locoweed consu
mption increased within 10 days until they were consuming as much as t
he non-averted controls, In the second trial, we compared the strength
and longevity of aversion between steers that were familiar with loco
weed (n = 6) and naive steers (n = 6), Both groups were averted to loc
oweed as described in Trial 1 and returned to locoweed-infested pastur
e, The Familiar group decreased locoweed consumption for the first 2 d
ays, then gradually increased locoweed consumption and extinguished th
e aversion, The Naive group subsequently refused to graze locoweed, In
the third trial, aversions were reinforced following grazing locoweed
in the pasture, Three steers from the Familiar group were allowed to
graze locoweed for 30 min, periods, then were returned to the pen and
dosed with LiCl (100 mg/kg BW), These steers were kept in the pen and
allowed to recover for 36 hours, This reinforcement process following
grazing was repeated 4 times, Steers in the Reinforced group abstained
from eating locoweed when released into the locoweed-infested pasture
for the remainder of the trial, Reinforcement of aversions following
field grazing of locoweed prevented cattle that were familiar with loc
oweed from grazing it.