EFFECTS OF ECOTYPE ON THE BEHAVIOUR, STRESS-INDUCED HYPERTHERMIA AND TONIC IMMOBILITY OF NIGERIAN INDIGENOUS CHICKENS SUBJECTED TO DIFFERENT AUDITORY STIMULI

Abstract

ABSTRACT The Nigerian indigenous chickens (NIC) are exposed to auditory stimuli such as noise and music in their natural environment. This study determined the effect of ecotype on behaviour, stress-induced hyperthermia and tonic immobility (TI) of NIC subjected to different auditory stimuli. Thirty-two Fulani ecotype hens (FEH) and thirty-two Yoruba ecotype hens (YEH) were used for this study. The hens were selected from existing stock and raised in deep litter pens.Each ecotype of the hens was divided into four replicates with 8 hens assigned into each replicate. The eight hens were further divided into continuous group and intermittent group. Twenty-four Fulani ecotype chicks (FEC) and twenty-four Yoruba ecotype chicks (YEC) were randomly selected from chicks hatched from eggs collected from the hens and were raised in the same system. Each ecotype of chicks was divided into four replicates and six chicks were assigned into each replicate. Both hens and chicks were subjected to four variants of auditory stimuli, continuous noise (CN) and intermittent noise (IN) which were pre-recorded vehicle noise and continuous music (CM) and intermittent music (IM), which were playbacks of “Eine Kleine Nachtmusik – Best of Mozart Collection” played at 85 dB in wooden test arenas and the video playback was observed for perching behaviour (PB), oral-related behaviours (ORB), fear-related behaviours (FRB), body maintenance behaviours (BMB) and negative social behaviours (NSB). Eye temperature (ET), head temperature (HT), wing temperatures (WT) and TI were determined after the exposure to each auditory stimulus. The data obtained were tested for normality after which they were analysed using either Mann-Whitney U test or One-Way Analysis of variance. The results showed that YEH performed PB and BMB more frequently (p<0.05) than the FEH when exposed to IN and CN, respectively. The ET, HT and WT were higher (p<0.05) in FEH than YEH exposed to IN. Higher (p<0.05) ET, HT and WT were recorded for YEH (38.61, 38.25 and 40.86 °C) exposed to CM than the FEH (37.84, 37.36 and 40.36 °C, respectively). The YEH also had higher ET and HT when exposed to IM, but the WT was higher in the FEH than the YEH subjected to IM. FEC performed PB and BMB more frequently (p<0.05) than the YEC exposed to CM. The ET and WT were higher (p<0.05) in FEC subjected to CN while the WT was higher (p<0.05) in FEC than YEC exposed to CM, however, no ecotype effect was found in the TI of Fulani and Yoruba hens and chicks exposed to the auditory stimuli. It was concluded from this study that ecotype caused the YEH to perform PB and BMB more than the FEH in response to IN and CN respectively and FEH had lower surface body temperature compared to the YEH when exposed to CM and IM. FEC had higher ET and WT than YEC when exposed to CN. It is therefore recommended that Fulani chickens are prioritized in improvement programmes due to their superior ability to cope with auditory stress and music should be encouraged as environmental enrichment.