RESUMO
The introduction of heifers into the automatic milking system (AMS) can be associated with considerable stress for both animals and farm employees, as completely inexperienced heifers initially do not independently enter the unknown milking robot. This study investigated whether training heifers on an AMS phantom provides the possibility of preparing heifers for the following lactation at the AMS. For this purpose, 77 Holstein-Friesian heifers were randomly assigned to one of 2 experimental groups: control (CON) or phantom (PHAN). Four weeks before calving, the PHAN group was given free access to the phantom, which was similar to the actual milking robot, so that they could explore it and be positively conditioned by feeding concentrate in the phantom. The heifers of the CON group had no contact with the phantom or the AMS before the first milking at the AMS. The milking frequency per animal per day was recorded, and the proportion of animals that had to be fetched for milking was determined, to evaluate how the animals accepted the AMS after calving. To assess the stress level of the animals before and after introduction into the AMS, fecal cortisol concentrations and rumination times of the animals were measured. Additionally, lactation performance characteristics (milk yield, milk flow, electrical conductivity of milk, and milk composition) were recorded for 77 animals. The animals trained on the phantom showed a higher milking frequency (DIM 7: 2.70 ± 0.14 visits/d) than the control animals (DIM 7: 2.41 ± 0.14 visits/d) between the 4th and 10th day of lactation. In addition, between d 1 and d 5, the proportion of animals that had to be fetched for milking was lower in PHAN (DIM 1: 35.18 ± 4.16%) than in CON (DIM 1: 48.03 ± 4.46%). The PHAN heifers had unexpectedly high fecal cortisol levels (1 wk prepartum: 43.50 ± 0.93 ng/g of feces), although not considerably elevated compared with CON (1 wk prepartum: 40.76 ± 1.05 ng/g of feces). Training on the phantom had no appreciable influence on rumination time and lactation performance parameters. The increased number of milking visits and the reduced proportion of animals that had to be fetched into the AMS for milking indicate that training on the phantom prepares the animals well for being milked in the AMS. Therefore, training heifers on the phantom offers the possibility to facilitate the start into early lactation for the animals, providing a valuable contribution to improvement of animal welfare.