Adverse influence of social facilitation and learning context in training cattle to avoid eating larkspur

Through conditioned food aversion learning, livestock can be trained to avoid eating harmful plants. The objectives of this study were to determine whether social facilitation will extinguish an aversion to larkspur (a poisonous plant on mountain rangelands) and to determine whether the aversion can be reinforced to withstand social facilitation in a group-feeding and field-grazing situation. Two groups of heifers offered fresh larkspur were simultaneously infused intraruminally with lithium chloride (LiCl) to create an association between the taste of larkspur and LiCl-induced gastrointestinal distress. A third control group was infused with water. Heifers from one averted group (extinction) were paired with nonaverted controls and offered larkspur. When the extinction group sampled larkspur, and LiCl was not infused, the aversion was extinguished rapidly. Heifers in the other averted group (reinforcement), being infused with LiCl whenever they sampled larkspur, abstained from eating larkspur in the group-feeding situation. Heifers were then taken to larkspur-infested rangeland. After the control heifers began eating larkspur, the averted heifers started to sample it and the aversion was extinguished in three of four heifers. However, the aversion was renewed when the heifers were returned to the pen- and group-feeding situation where the aversion was created. Reinforced aversion was overcome by social facilitation in an unfamiliar field-grazing environment.