Experiment 3: Rewarding treatments for heifers

The treatments were applied at the end of the race in the treatment pen. All treatment periods were 1 min in duration. In order to facilitate application, treatments were applied from the side of the animal. To ensure that the cows associated the treatment with the person, the person remained in view of the animals while performing the treatment, and returned and stood in front of the animal every time after applying each treatment. Unlike experiment 1, the cows were familiarised with the race the day before the experiment. During this day, cows were taken to the race and allowed 2 min to walk through each section of the race before force was applied. No treatments were applied when the cow reached the end of the race during this training run. Two groups of five cows, one per treatment, were tested each week. Cows passed through the race three times a day over 3 days, for a total of nine trials. Treatment order was balanced across groups and one person treated all the animals. 4.2. Results Over the course of the experiment the average latency to enter the race did not show Ž . any consistent change over trials Fig. 3a and there was no treatment effect or trial by Ž . treatment interaction. There was a trial by treatment interaction P - 0.05 for the Ž . average time to walk through the race Fig. 3 . Cows on the electric prod treatment took more time to walk through the race than cows on the control treatment on trials 5, 7, 8 Ž . Ž . P - 0.05 , and 9 P - 0.01 . Cows on the shout treatment took more time to walk Ž . through the race than control cows on trial 5 P - 0.05 . Cows on the control, hit, and tail twist treatment did not differ from each other in the amount of time to walk through the race. The amount of force required to move the cows through the race also showed a trial Ž . by treatment interaction Fig. 3c . Cows on the electric prod treatment required more Ž force to move down the race than control cows after trial 3 trial 4, P - 0.05; trial 5, . P - 0.01; trial 6, P - 0.05; trials 7 and 8, P - 0.01; and trial 9, P - 0.001 , while cows Ž on the shout treatment also differed from control cows after trial 3 trial 4, P - 0.05; . trial 5, P - 0.01, trials 6–9, P - 0.05 . Cows on the tail-twist and hit treatments did not differ with control or each other.

5. Experiment 3: Rewarding treatments for heifers

The purpose of this experiment was to determine if the aversion race could be used to differentiate between treatments thought to be rewarding rather than aversive to heifers. 5.1. Methods Thirty-nine heifers, aged 1–1.5 years old, were randomly allotted to three treatments. a. Control. The experimenter turned and faced the animals then remained still with hands in pocket. b. Gentling. Heifers were petted on the neck and head with an open hand and quietly spoken to. Ž . Ž . Ž . Fig. 3. Behaviour of cows meanSE during experiment 2. a Latency to enter the race, b time to move Ž . through the race, and c force required to move through the race. c. Hand feeding. The experimenter, in a crouched position, offered hay from one hand and a molasses-flavoured feed from the other. One person treated all the animals. All treatment periods were 1 min in duration. As in experiment 2, animals were walked through the race, once, the day before the experiment. In the first week of the Ž . experiment, we used one group of three heifers one per treatment . After the first week Ž . we used four groups of three calves one per treatment over 3 weeks. Heifers went through the race three times a day over 3 days for a total of nine trials. 5.2. Results Over the course of the experiment the average latency to enter the race decreased Ž . P - 0.01, Fig. 4 . The average amount of time, and force required to pass through the Ž . race also decreased over successive trials P - 0.05 . However, there was no treatment effect or trial by treatment interaction. Contrast comparisons found no differences between any treatments in the overall mean latency to enter the race, the time to walk Ž . Ž . Ž . Fig. 4. Behaviour of calves meanSE during experiment 2. a Latency to enter the race, b time to move Ž . through the race, and c force required to move through the race. through the race, or the mean force required to move the animal through the race. Nor did these variables differ at any one specific trial. Of the 13 heifers on the food trial, Ž . only 8 started to eat consistently defined as eating on two consecutive trials by the fourth trial. Since this may have effected the results, the data were re-analysed using only these 8 animals. However, the results of the analysis were the same as when the entire data set was used.

6. Discussion