Potential of application of a modified open-field test for selection of laying hens

The aim of the study was to propose a modification to the classical open-field test (OFT) to make even more reliable and informative assessment of behavioural reactions. Birds' quick locomotion assessed with OFT does not necessarily indicate a high level of fear and an attempt to escape, but it can involve a considerable level of sociability and willingness to return to the flock Those two motivations, fear and sociability, are not distinguishable with the classical OFT; the test does not provide unambiguous assessment of the motivation of birds' behaviour and emotions. Given this shortcoming of the open-field test, a question arose whether the use of environment-enrichment objects in the open-field test would ensure greater objectivity in assessment of hens' behaviour. The study involved 150 laying hens - 50 Green-legged Partridge chickens (GLP), 50 Polbars (Pb), and 50 Leghorns (L), reared in a single commercial farm. All the birds were 30 weeks old at the time of assessment. The hens were subjected to a modified open-field test (MOFT). The modification involved introduction of environment enriching objects, which were novel for the birds. The box comprised containers with water, commercial feed, feed supplemented with finely fragmented cereal spikes, finely cut cereal straw and insect larvae as well as a sandpit, a mirror, and an imitation of a nest. The test lasted 600 seconds. Six different behavioural indicator traits were recorded (MOFT1-MOFT6). Spearman's rank correlations between the traits were estimated. The MOFT results enabled to distinguish such hens' traits as curiosity, inquisitiveness/exploratory behaviour, and excitability. The most important indictors include the duration of exploration of the area, the number of explored objects, time spent on exploration of the objects, and the number of squares covered. It appeared that a single behavioural indicator - the latency of undertaking physical activity - can be used for selection and breeding practice. This indicator is correlated highly with the others and is simultaneously easy and quick to assess in farm conditions. Hence, the latency of undertaking activity can potentially be used in assessment of hens' behaviour to evaluate curiosity/ fearfulness and emotional excitability as correlated behaviours.