Maternal Feeding Call Playbacks Reduced Anxiety and Depression-Like States in Meat Chicken Chicks

Brooding chicks with maternal care can improve the welfare of chicks; specifically, by improving prosocial behavior and reducing feather pecking (Edgar et al., 2016). Yet providing chicks mother hens in industry is impractical and a biosecurity risk. Artificial components of maternal care may provide some benefits to chicks and improve welfare. Indeed, there is some evidence that lighting that mimics the maternal environment, synthetic maternal olfactory cues and mother hen vocalizations can affect chick behavior and welfare (Edgar et al., 2016). Playback vocalizations are a promising method to provide part of the maternal environment to chicks, due to the low cost of installation and maintenance of technology and the multifunctionality of speaker systems that could emit various calls for different contexts and desired outcomes. Furthermore, playbacks of maternal calls have been shown reducing stress responses of layer hen chicks (Edgar et al., 2015) and increase growth of meat chickens by 25% (Woodcock et al., 2004). However, the effect of maternal call playbacks on meat chicken welfare is largely unknown. We aimed to improve meat chicken welfare through the use of a maternal feed call playback by improving stress resilience.

Mixed sex Cobb 500 birds (n = 224) were housed in groups of 14 across 16 pens (3.2m × 2m) with wood shaving flooring, a perch, one round feeder and two nipple drinkers. Treatment groups were audibly isolated across separate rooms. Chicks in pens within the same room/treatment were visually isolated. Playback recording of either a maternal feeding call (maternal call treatment group; MC) or white noise (control group; CON) were played through speakers mounted above the center of each pen (Flex 15, Australian Monitor Integration Intelligence, Silverwater, NSW, Australia). Maternal call playbacks were 5 minutes in duration and contained 30 seconds of a feed call followed by 30 seconds of silence. The playback contained recordings from two hens when their brood was 3 or 4 days of age. The playback was played each hour in a 24-hour cycle from the first day of life. At either 5 or 6 days of age, chicks (n = 14 MC; n = 12 CON) were assessed for behavioral indicators of anxiety and depression using the validated domestic fowl anxiety-depression chicken model (Sufka et al., 2006). Briefly, each chick was isolated in a test arena (1.7m × 1.7m) with 10cm wood shaving flooring, located in an adjacent room for 60 minutes. Vocalizations were recorded during the test (BAR recorder, Frontier Labs, Salisbury, Qld). The number of distress calls emitted during the test were quantified using Raven Sound Analysis software (The Cornell Lab of Ornithology, New York, USA) and summed into 5-minute intervals. The number of vocalizations for each interval was analyzed with a Generalized Estimating Equation to account for non-parametric data and repeated measures.

Chicks that had been given maternal feeding call playbacks in their home pen vocalized less relative to control chicks during the social isolation test. However, control chicks showed a steeper progressive decline in distress calls overtime compared to chicks that had received the maternal call (interaction time × treatment: χ²_(11,299)=21.6, P = 0.028; Figure 1).

Previous pharmacological interventions to validate the chick anxiety-depression model shows that birds in an anxiety state will frequently emit distress calls and birds in a depressive-like state will rapidly reduce the number of distress calls over time (Salmento et al., 2011; Sufka et al., 2006). We provide evidence that playing maternal feeding calls at hourly intervals throughout the first 5 days of life reduced anxiety and depression-like states in meat chickens, suggesting that playing maternal calls may be an effective way to improve the welfare of meat chickens.

ACKNOWLEDGEMENTS: We would like to thank AgriFutures for funding this work and Haylee Herriot for her assistance with the daily animal care and experimental data collection.