CONTACT-LENSES FOR LAYING HENS

A study was conducted to examine the effect of contact lenses on egg p roduction, egg weight, fear response, and mortality in White Leghorn h ens. Two hundred laying hens in their second laying period (76 to 104 wk of age) were housed in 48.5 x 45.5 cm sized cages with five birds p er cage. Red contact lenses were placed on the eyes of 100 chickens; t he other 100 chickens served as controls. Some of the chickens with th e 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 wit h lenses. Duration of tonic immobility (TI) was significantly longer a mong the control chickens than among those with contact lenses (158 vs . 66 sec). No differences were found in egg production, egg weight, an d mortality between the control and the experimental hens. However, co ntact lenses appear to be associated with an increase in eye irritatio ns and thus their application is discouraged.