The effect of experience of ramps at rear on the subsequent ability of layer pullets to negotiate a ramp transition

Abstract

In commercial situations, laying hens must negotiate levels to reach resources such as food, water and litter. Providing ramps in aviary systems reduces collisions and resultant keel bone fractures in adults. We investigated whether providing ramps during rear improved the ability of birds to transition between levels. Chicks were reared commercially in two flocks both of which provided access to raised structures from three weeks of age. One flock had no ramps, but the other flock was provided with additional access to two types of ramp (wooden ladders, and grids formed from commercial poultry slats placed at an angle). At 8 weeks of age, 64 birds (32 from each rearing condition) were transferred to an experimental facility. At 10 weeks of age, 32 pullets from each group were trained to run to a food reward. During testing at 12-14 weeks of age the pullets accessed the food reward by moving up or down a ramp. The pullets' behaviours and time taken to complete the task were recorded. Ramp use over three days was also observed in a room replicating a small-scale single-tier system. Four groups of 16 birds aged 12-14 weeks were housed for three days and the number of transitions between the raised tier and litter were recorded. For upward transitions, more ramp-reared birds than control birds succeeded in reaching the food reward for both ladder (52 % vs 13%) and grid (74% vs 42%). Birds from the ramp-reared group took significantly less time to complete an upwards transition (68.8s±49.3) than the control group (100s±37.6) (p=0.001). In addition, the control group showed more behaviours indicative of hesitancy (moving away, head orientations, ground pecking and crouching) before transitioning, and signs of difficulty when making upward transitions (crouched walks, pauses, turning, returning and escape attempts). In the group housing observations, the ramp reared groups had almost double the number of transitions between the slats and litter on day one compared to the control group. This difference was reduced by day three. In summary, this suggests there are positive effects of providing ramp experience during rear shown by increased mobility and apparent confidence in older pullets. It is not known whether these benefits persist through to the laying period, but no detrimental effects were noted so we suggest that ramps should be included from the early rearing period onwards.

Rearing experience with ramps improves specific learning and behaviour and welfare on a commercial laying farm

“…The results from this study show that providing ramps during rear in a commercial facility enables chicks to access elevated structures during their first week of life, confirming previous experimental results 14 . Chicks had a preference to use the ramps to access elevated structures and this was observable throughout the rearing period.…”

“…We also observed more low perch jumps up the structures and more jumps down from the low-level perches and slats in the control groups. Behaviours indicating hesitancy have been identified and used in both commercial and experimental studies to look at ramp transitions 11 , 14 , 15 . In this study, the difference in hesitancy like behaviours between the rearing groups suggests that providing access ramps improves the confidence to transition up and down structures.…”

“…Given the growing pool of research investigating the benefits of providing ramps for laying hens, we have been studying the effects of ramp provision for younger birds too. In a small-scale study, we found that chicks reared with ramp access from 3-weeks-old in a commercial farm utilised ramps within a small experimental facility to a greater extent and with more confidence when tested at 14 weeks of age than birds reared without ramps 14 . This study also found that layer pullets preferred grid ramps over ladder ramps and showed fewer hesitancy behaviours on grids 15 .…”

The impact of early structural enrichment on spatial cognition in layer chicks

“…In other studies, we (Norman et al, 2018) and others (Gunnarsson et al, 2000) have found that early experience of structures such as ramps improves the use of the structures compared to birds that have had no experience, illustrating the importance of early life experiences. However, in these previous studies chicks were reared for a longer time (up to 8 weeks or more) under different rearing conditions.…”

“…Facilitated access (using ramps or staged perches) may be even more beneficial. Our own work has shown that access to ramps during the rearing period improved ramp transitions in older pullets, shown by reduced hesitancy behaviour and shorter transitioning latencies (Norman et al, 2018). A preference for grid ramps over ladder ramps was found suggesting the type of ramp should also be considered (Pettersson et al, 2017).…”