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An automated Precision Feeding (PF) system has been developed by Dr. Martin Zuidhof with the goal of providing the right amount of feed to individual broiler breeders at the right time. Precision-fed chicks undergo training up to 21 D of age to learn how to eat from the system. It is crucial to identify chicks that have not learned how to eat from within the PF station during the training period to provide the chicks with a good start. The PF system prototypes relied on radio frequency identification (RFID) transponders to identify and monitor individual bird success. However, the RFID transponders would be costly to implement in a large commercial flock. As a result, an automated marking system (AMS) prototype was developed and incorporated into the PF system to mark chicks with dye as they eat from the system. In such a system, chicks with little or no dye marking could be identified as chicks that learned how to eat from the PF system at a slow rate compared with other chicks and therefore require training. The objective of the present study was to determine if the dye marking from the AMS influenced aggressive behavior of precision-fed chicks during the training period.
The study was conducted using a PF system with 3 treatments: 1) control (CON) treatment in which no dye solution was applied (n = 2 pens of 26 and 27 birds), 2) manual marking (MM) treatment in which a dye solution was manually applied (n = 2 pens of 26 and 27 birds), and 3) automatic marking (AM) in which the birds were marked with a dye solution from the AMS prototype (n = 1 pen of 52 birds). The experiment was conducted over 26 days using 158 mixed-sex Ross 708 broiler breeders (n = 126 pullets; n = 32 cockerels). If needed, chicks were gently guided through each stage and to the feeder by training personnel if they were hesitant or did not travel through the station on their own. A Chemyx Syringe Pump would release 1 drop (approximately 0.03 mL) of dye solution from a fixed position above the feeder onto chicks eating from the feeder. Each chick in the MM treatment was marked manually once per week over the course of the experiment, at least 48 h before behavior observations. BW gain, FI, and station visit frequency were recorded to make decisions during chick training. Behaviors were observed by trained observers and recorded on an individual bird basis and then converted to the frequency of behavior performed per bird per hour. The total number of aggressive behaviors was calculated from the sum of aggressive pecks, fights, gentle feather pecks, pecks at an identification tag (ID), severe feather pecks, and threats.
Marking intensity in the MM treatment was higher on day 3, 4, 5, 7, 8, and 9 than that in the AM treatment. The effect of treatment on aggressive pecks depended on the age of the chicks. On day 26, the AM treatment performed more aggressive pecks (12.9) than the MM (3.12) and CON (0.91) treatments but did not differ from the MM treatment on day 21 (5.51 pecks/bird/h). During individual feeding mode, the AM treatment was given the highest marking intensity score on day 26. By day 26, chicks had begun to develop their chick plumage which absorbed the dye more than the immature chick plumage. Consequently, mark intensity was greater on the white feathers which, as a novel item, may have promoted pecking. Overall, the MM and CON treatments performed 6.3 and 5.3 times more gentle feather pecks than AM chicks, respectively. There was no effect of age or treatment on the frequency of severe feather pecks. The present study suggests fights and threats are less common among broiler breeder chicks but rather observed at an older age beyond the time that the AMS would be used as an identification method in a PF system.
Dye markings from the AMS did not increase frequencies of aggressive behaviors from 0 to 21 D of age. The frequency of aggressive pecks in the AM treatment increased on day 26, which may have been due to development of white chick plumage and the intense appearance of dye markings on the chicks’ head and neck. The AMS should not be used in PF stations beyond the first 21 D of the training period to avoid stimulating aggressive behaviors.