Contact Lenses for Laying Hens

Abstract

A study was conducted to examine the effect of contact lenses on egg production, egg weight, fear response, and mortality in White Leghorn hens. Two hundred laying hens in their second laying period (76 to 104 wk of age) were housed in 48.5 × 45.5 cm sized cages with five birds per cage. Red contact lenses were placed on the eyes of 100 chickens; the other 100 chickens served as controls. Some of the chickens with the lenses developed eye irritations within 2 wk after the beginning of the experiment. After 7 months, a large proportion of the experimental hens were severely affected. Six hens from each group were killed and necropsied. Heart weight was significantly heavier among the hens with lenses. Duration of tonic immobility (TI) was significantly longer among the control chickens than among those with contact lenses (158 vs. 66 sec). No differences were found in egg production, egg weight, and mortality between the control and the experimental hens. However, contact lenses appear to be associated with an increase in eye irritations and thus their application is discouraged.