Approach-aversion in calves following injections

We assessed aversion to injections using an avoidance-learning paradigm. Holstein calves (n = 24) were randomly assigned to one of four routes of administration for 0.5 ml of saline: intramuscular (IM), intranasal (IN), subcutaneous (SC) and a null control. Calves were first trained to approach a milk reward of 1 L. Once the latency to approach the reward was consistent, calves received their assigned treatment when approaching the bottle. For...