T-maze behaviour in broiler chicks is not sensitive to right-left preferences, test order or time-of-day

There is substantial individual variation in the time taken by broiler chic ks to traverse a T-maze and thereby reinstate visual contact with their com panions. Chicks completing this task quickly thigh performance, HP) subsequ ently grew faster in the laboratory and on farm, exhibited greater socialit y, and showed less pronounced adrenocortical responses to a partial water i mmersion stressor than did their slower (low performance, LP) counterparts [Marin, R.H.. Jones, R.B., 1999. Latency to traverse a T-maze at 2 days of age and later adrenocortical responses to an acute stressor in domestic chi cks. Physiol. Behav. 66, 809-813.; Marin, R.H., Arce, A., Martijena, I.D., 1997. T-maze performance and body weight relationship in broiler chicks. Ap pl. Anim. Behav. Sci. 54, 197-205.; Jones, R.B., Marin, R.H., Garcia, D.A., Arce, A., 1999. T-maze behaviour in domestic chicks: a search for underlyi ng variables. Anim. Behav. 58, 211-217.]. Given its simplicity, rapidity an d non-invasiveness, the T-maze test might represent a commercially attracti ve selection criterion for future breeding programmes if this behavioural t rait exhibits sufficient genetic variability. However, it is first necessar y to ensure that performance in the T-maze is not sensitive to potentially confounding variables, such as existing preferences to turn right or left a t the junction of the maze, the order of testing, or the time of day. In th e present study, 240 newly hatched, mixed-sex broiler chicks (Cobb) were ra ndomly allocated to 12 groups of 20 upon receipt. When they were 2 days of age a group of 20 chicks was placed in the brood area of each of two T-maze s at 0830 h; the brood areas were positioned on either the right or the lef t sides of the mazes. After acclimatisation, one chick from each group was placed in the isolation chamber of the T-maze and we recorded the time it t ook to traverse the maze. This procedure was repeated until all 20 chicks a nd all 12 groups had been tested. The locations of the brood areas were rot ated after each block of 20 tests. Testing was completed in the same day an d two groups were tested at each of the following times: 0900, 1030, 1200, 1330. 1500, and 1630 h. Analysts of variance (ANOVA) revealed no detectable effects of: positioning the brood area on the right or the left side of th e T-maze (F-1,F-200 = 0.06, P < 0.80), test order (F-19,F-200 = 0.48; P < 0 .96), or time-of-day (F-5,F-234 = 0.44; P < 0.81). These findings strongly suggest that the future classification and possible selection of broiler ch icks according to their T-maze responses are unlikely to be confounded by r ight-left preferences, test order, or the time of day. (C) 2000 Elsevier Sc ience B.V. All rights reserved.