Effects of a Perch in Conventional Cages for Laying Hens

Abstract

A total of 720 Single Comb White Leghorn laying hens (SCWL's Shaver 288) were studied from 22 to 82 weeks of age for the effect of a perch on production, egg weight, exterior egg quality and egg rolling-out efficiency, plumage condition, foot health, claw length, throat skin health, mortality, live weight, behaviour and usage of the perch at different times of day. Video technique and manual registrations were used for the behaviour studies. Treatments were cages with perch (P) and without perch (NP). Each cage contained 5 birds, implying a perch length of 12 cm per bird and 480 cm² cage floor space per bird. There was no significant difference in laying rate per hen-day (hd) or mortality between P-and NP-birds. However, P-birds had significantly lower egg weights giving a significantly lower egg output in g of egg mass produced per hd. P-birds had lower live weight than NP-birds. There were no significant differences in foot health (lesions on pads or digits), claw length or health of throat skin. The score for plumage condition on the whole body was significantly inferior for P-birds. The plumage condition for individual body parts was significantly inferior on the neck, breast, wings and tail in P-birds. No significant difference in scores for plumage on the back was found. There was no significant difference in frequency of dirty eggs or eggs that had completely rolled out into the egg cradle. However, in P-cages the frequency of cracked eggs was significantly higher than in NP-cages. The birds in P-cages roosted on the perch to a very high degree after dark (80–100%) but perched less during daytime (25–50%) and very little before and after the start of the automatic flat chain feeder (0–20%). There was no significant difference between P- and NP-birds in frequency of feeding- or drinking behaviours. However, there was a tendency for P-birds to perform more preening and less pecking at another birds' plumage than NP-birds. It is concluded that it is practically possible, even in a conventional cage to offer hens the possibility of using a perch without making other technical alterations to the cage. The birds will perch frequently, especially after dark; in the present experiment a mechanism simulating sundown was used. Birds would produce the same number of eggs but there might be a risk of a moderate increase in the frequency of cracks and possibly a reduction in egg weight. The latter effect could not clearly be explained. Probably due to more abrasion against each other, birds in these P-cages showed somewhat lower scores for plumage condition. Effects of using cage floors with better flexibility in P-cages and modifications to the accessibility of the perch during different times during the full day are discussed.

Key Words:

• Roost
• plumage
• foot lesions
• egg quality
• behaviour