By Tunmise Faith Ehigbor
Pecking blocks (PB) with different nutritional and sensory characteristics are used as foraging enrichments for laying hens, but the relative preferences are unknown. We hypothesized strain differences in PB preference. One hundred and twenty Dekalb-White and 120 Bovans-Brown laying hens were each housed in test cages in six groups of 20 (N=6/strain). Three types of PB were offered in a series of pair-wise comparisons (PWC) over three 4-week periods. Block A contained mineral + grains, B contained mineral + grain + molasses, and C was primarily mineral-based. PB disappearance was measured by weekly weighing. Pecking and scratching behaviour was measured at the individual level by live observations (observers blinded to hypotheses) of seven focal birds/per cage once a week (3x-daily). Behaviour at group level was measured from video cameras mounted over each PB. Birds pecking or scratching (POS) at the blocks were counted every five minutes throughout the light period using instantaneous scan sampling (total=169 scans/day, split into 3 times-of-day (TOD): a.m., mid-day, and p.m.).
Data were analyzed using SAS Glimmix for fixed effects of strain, PB type, period, PWC, and TOD. Browns used B>other block and strain combinations (F=14.25, df=2,26, p<0.0001). At group level, PWC affected POS behaviour. For Whites (F=2.88, df=3,73, p=0.04), the PWC of blocks B and C resulted in more birds POS at C. More brown birds directed POS at B (F=4.03, df=3,60, p=0.01). TOD interacted with PB type (White:F= 7.13, df=4,78, p<0.0001, Brown:F=11.16, df=4,60, p<0.0001). Whites pecked and scratched the C block at p.m.>other blocks at any TOD (F=7.13. Browns directed POS at the B block at mid-day and a.m.>other blocks at any TOD. The two common strains of laying hens in this study preferred different types of PB and used them at different TOD. Tailoring enrichment materials based on strain-specific preferences could enhance foraging behaviors in laying hens.
