Comparative study on stress-induced hyperthermia, level of fear and behaviour of two genetically selected strains of domestic chicks to playback calls

Feed and alarm calls induce arousal in chicks, the former for feeding and the latter for danger. However, the response of birds genetically selected for meat or egg production to these calls have not been investigated. Thirtysix chicks each of the ISA Brown pullet and FUNAAB Alpha broiler (2 weeks old) were randomly allocated into three groups per strain and subjected to three playbacks: no call (NCP), feed call (FCP) and alarm call (ACP) continuously for 1 h. The test was carried out for 3 days/week for two weeks. The behaviours monitored were foraging, feeding, pecking (grouped as oral-related behaviour, ORB), freezing and clustering (grouped as fearrelated behaviour, FRB). The eye (ET) and under wing (WT) temperatures were measured before and after each call and the change (AET and AWT) calculated. Tonic immobility (TI) test was performed after each call and the number of attempts to induce TI (NOATI) and the duration of TI (DTI) was recorded. Data on these two behavioural categories were subjected to General Linear Model analyses separately for each call having strain and day as fixed factors. The AET, AWT, NOATI and DTI were analyzed using Mann-Whitney U test. On both days, AET and AWT was similar after exposure to 1 h of FCP, ACP and NCP. FCP caused more (P 0.001) AWT in pullet than broiler. Fear responses during FCP was not affected (P 0.05) in pullet than broiler. Finally, there was no significant (P 0.05) strain x day or strain effects on ORB and FRB, with ORB greater (P < 0.05) on the 2nd day. In conclusion, pullet and broiler chicks showed greater arousal (higher AWT) to FCP and ACP, respectively. The pullets showed more fear responses during NCP and ACP than the broilers. The ORB and FRB were similar in both strains during each of the three calls.