Nest use and patterns of egg laying and damage by 4 strains of laying hens in an aviary systemc1
Laying hens are strongly motivated to use nests for egg laying, and alternative production systems (e.g., aviaries) provide artificial sites to meet this need and ensure efficient collection of clean, undamaged eggs. However, nests are typically not provided to allow simultaneous use by all hens; therefore, competition or mislaid eggs can result. To understand the influence of strain on laying eggs outside nests and damage to eggs, we compared daily patterns of nests use and egg laying among 4 laying hen strains (Hy-Line Brown (HB), Bovans Brown (BB), DeKalb White (DW), and Hy-Line W36 (W36)). Hens were observed over 3 consecutive days in aviaries with colony nests in the enclosure's top tier (2 nests/unit, 4 aviary units/strain, 144 hens/unit). The number and location of hens in nests and the number, location and condition of eggs throughout aviaries were recorded. Most eggs (90 to 95%) were laid in nests; however, brown hens consistently laid more non-nest eggs and damaged more eggs than white hens (P ≤ 0.05). Higher nest occupancy by brown hens was correlated with more non-nest and damaged eggs (P ≤ 0.05). In the morning, brown hens occupied more nest space and laid more nest eggs than white hens (e.g., HB vs. DW: 82.97 and 34.66% of space; 91.35 and 68.73% of nest eggs; P ≤ 0.05). At midday, white hens occupied more nest space and laid more nest eggs than brown hens (e.g., HB vs. DW: 28.47 and 15.81% of space; 27.39 and 8.29% of nest eggs; P ≤ 0.05). Brown hens preferred right nest compartments and laid more eggs there, whereas white hens preferred left compartments and W36 laid more eggs there (P ≤ 0.05). These findings indicate that different strains of hens have different patterns of nest use and laying behavior. In brown hens, heavy morning nest use was related to laying eggs outside nests and more damaged eggs, suggesting insufficient space for oviposition in nests. Specific facility design should be matched to hens' preferences to accommodate behavioral needs of different strains.