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ABSTRACT: Besides health monitoring, a regular check of dairy heifers' growth rate is desirable, but it is rarely done because procedures that require restraint and handling can be associated with substantial stress for both animals and farmers. Inexperienced heifers, especially if they are highly responsive to humans, may find restraint and handling potentially aversive. This study investigated whether training heifers of different age and responsiveness toward humans (RTH), through operant conditioning, could reduce stress in animals, ease close contact and handling, and be feasible in terms of farmers' effort. We assessed 60 Holstein heifers of 2 age classes (young, n = 29, 291 ± 39 d; old, n = 31, 346 ± 62 d) according to the avoidance distance test and classified them as confident (n = 20), neutral (n = 21), or nonconfident (n = 19). Half of the heifers of each age and RTH class were trained (n = 29), whereas the other half was not (n = 31). The trained heifers were subjected to target training for 8 sessions and positively reinforced with feed to allow being touched on the muzzle, rump, and perineum. If a heifer refused positive reinforcement, the trainer stepped back as negative reinforcement. In the last week of the experiment, the effect of training on the reaction to handling was assessed in all heifers. We measured heart rate, root mean square of successive interbeat interval differences (RMSSD), and fecal cortisol metabolites (FCMet). The presence of behavioral distress signs was recorded as well. The avoidance distance test was performed a second time 24 h after the measuring session. All of the trained heifers, regardless of RTH class, successfully accomplished the target training task in 6 sessions, each spending on average 25.3 s per session. All of the trained heifers allowed touches on the rump and perineum at the end of the fourth session. Training nonconfident heifers required more time compared with the others. Trained heifers showed higher RMSSD than nontrained heifers (14.2 vs. 16.9 ms, respectively), indicating a lower vagal tone, and thus, a slightly lower stress level than nontrained heifers. Training did not lead to differences in HR, FCMet, or presence of stress behavioral signs. Nonconfident heifers had the highest mean baseline FCMet values compared with neutral and confident heifers (38.4 vs. 30.3 vs. 29.1 ng/g, respectively). Nonconfident heifers also showed the lowest value of FCMet 12 h after the measuring session (36.7 vs. 44.6 vs. 49.7 ng/g), likely due to a decreased responsiveness of the adrenal gland to a stressor. The average avoidance distance decreased between the beginning and the end of the experiment, especially for neutral and nonconfident heifers, regardless of whether they were trained or not. These results show how using operant conditioning on some heifers not only decreased their vagal tone, but also reduced the responsiveness to humans of all the animals, trained and not trained; in the latter case, this reduction was through nonassociative learning, such as habituation.

Abstract: Training cows to use an automatic milking system (AMS) is an important process as this method of milking depends on cows voluntarily using the AMS. This study examined two levels of training before calving on the behaviour of cows and heifers in an extensive pasture-based AMS. Animals received either no training (NIL), training which included handling, in the AMS and on-farm gating system (MINIMAL) or training in the AMS including exposure to typical noises and mechanical movements, plus on-farm gating system (EXTRA). Training was carried out over four sessions on four non-consecutive days. Training improved ease of entry into the AMS at the first assisted milking (NIL=17.9s, MIN=1.4s, EXTRA=6.7s, P <0.05). The additional exposure to the noises and sounds of the AMS had no effect (P >0.05) on behaviour during milking. Voluntary milkings were achieved by 92% of heifers and 81% of cows within 6days following their first assisted milking. Irrespective of the level of training, heifers learned to use the on-farm gating system and achieved their first voluntary milking quicker than cows (Time to milking: Heifers=1.88d, Cows=2.55d, SED=0.18, P <0.001). Pre-calving training improved aspects of the behaviour required for successful adaptation to automatic milking but had little impact on time to achieve a voluntary milking. Heifers adapted quicker than cows to automatic milking in a pasture-based farming environment. [Copyright &y& Elsevier]

Abstract: The aim of the present study was to examine whether cows in a commercially-managed barn with automatic milking can learn to visit the milking unit in response to an acoustic signal during the grazing season. The study included 10 Swedish Red and White dairy cows, randomly selected from a herd of 45 cows housed in a barn with an automatic milking system. A small box emitting an acoustic signal was attached to the collar of the 10 cows. During the training period, the signal was induced manually from a distance and during the evaluation period, signals were activated automatically from a computer connected to the automatic milking system. The cows were trained indoors using an operant conditioning technique. All cows had 12 training sessions with 7–12 signals given at variable intervals. An evaluation period followed the training period. During evaluation, the trained cows received an individual signal when 8h had passed since the previous milking. These cows received another signal after 10h if they had not visited the milking unit. The signal was activated regardless of their location. During the last training session, 8 of the 10 cows approached the milking unit more often following a signal than after a control period with no signal (P <0.05). There was a greater probability for the cows to respond to the signal if they were indoors (P <0.05). The average milking interval for cows trained and evaluated in early season was 8.2±0.44h (±S.E.M.). The interval for a reference group (with no signal) in early season was 9.7±0.18h (P <0.05). The intervals were 8.7±0.56h and 9.0±0.20h for the five cows trained in late season and a reference group (with no signal), respectively. During the evaluation in a full herd situation, the response ranged between 15 and 75% for individual cows. Low levels of reinforcement at the milking unit may have compromised responsiveness. [Copyright &y& Elsevier]