Creating aversions to locoweed in naive and familiar cattle.

Abstract

The objective of this study was to determine if cattle that were familiar with white locoweed (Oxytropis sericea Nutt, ex T&G) could be aversively 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, then dosed via a stomach tube with lithium chloride (LiCl, 200 mg/kg BW). When released into the locoweed-infested pasture, they gradually increased locoweed consumption over the next 5 days. The conditioning procedure was repeated with a lower dose (100 mg/kg BW), but locoweed consumption increased within 10 days until they were consuming as much as the non-averted controls. In the second trial, we compared the strength and longevity of aversion between steers that were familiar with locoweed (n = 6) and naive steers (n = 6). Both groups were averted to locoweed as described in Trial 1 and returned to locoweed-infested pasture. The Familiar group decreased locoweed consumption for the first 2 days, then gradually increased locoweed consumption and extinguished the 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 locoweed from grazing it.