Effect of Two Different Induced Molting Programs on Serum, Egg Yolk Igy Concentrations and Immune Parameters in Laying

Recent studies have indicated that egg yolk immunoglobulins (Ig) can be used for therapeutic purposes and that yolk Ig levels are increased after molting of laying hens. The present study was performed to compare between the effects of two methods of induced molting namely alfalfa and zinc methods on serum and yolk IgY concentrations as well as their effects on the egg quality and immune status of the molted hens. Three experimental treatments each of 20 Lohman laying hens 80 wks old were fed either control layer ration, 90% alfalfa in 10% layer ration or layer ration containing zinc oxide (20.000 ppm) for 9 days. For the alfalfa and zinc group, photoperiod was reduced to 8h/d. Water was provided ad libitum for all groups. At day 10 , hens were returned to basic laying ration and 16 h light/d. Feed intake , birds weight and egg production were monitored during the molting period after which 8 birds from each group were slaughtered and ovaries ,oviducts and spleens were excised and weighed. Egg parameters (weight, length, yolk diameter and yolk height) were recorded till resumption to 50% egg production. Serum and egg yolk IgY were measured using ELISA technique and white blood cell count was performed. Results showed that hens in the zinc treatment ceased egg production by 8.4 days, remained out of production until 21.8 days and returned to 50% production after 46.3 days while the values for the alfalfa group were 14.9, 24 and 49.4 days respectively. Egg weight, yolk diameter and yolk height values were increased in alfalfa group. Molting by either method resulted in significant loss in body weight, feed intake and weight of ovaries and oviducts .Spleen weight was slightly increased in the two molted groups. Values of serum IgY recorded 35 days post molting induction were 3.42 and 3.3 mg / ml serum in alfalfa and zinc groups respectively as