Physiological Response and Postmolt Performance of Laying Hens Molted by Non-Feed Removal Methods

One experiment was conducted to evaluate the physiological response and postmolt performance of laying hens subjected to non-feed removal molting programs. One hundred and eighty 78-week-old Hy-line W36 laying hens were distributed among 45 groups of four birds and located in cages so that mean body weight of each cage was very similar. Three adjacent cages were considered as a replicate and 3 such replicates were assigned to each treatment. There were five treatments (molting procedures): Treatment 1 was continuous feed removal (CFR) and considered as the control. Hens on treatment 2 (T2) fed ground corn as sole feed ingredient and dietary vitamin and macro and microelement levels were maintained as Hy-line W36 guideline specifications. Treatment 3 was similar to T2 except that salt was removed from diet. Treatment 4 was similar to T2 except that corn was replaced with wheat. Treatment 5 was similar to treatment 4 except that salt was removed from diet. Birds on T2 to T5 were fed at the rate of 50 g day^-1. The results indicated that hens subjected to CFR went out of production by Day 5 while those on corn or wheat diets with or without salt ceased egg production from Day 7 to Day 13. Nevertheless, postmolt egg production did not significantly differed among the treatments. Body weight loss in feed-deprived hens during molt was significantly (p<0.05) greater than non-feed removal treatments when measured on Day 7 and Day 12. Starvation during continuous feed removal resulted in increased heterophil to lymphocyte (H/L) ratio (p<0.05), hematocrit and plasma T4 whereas decreased plasma T3 level (p<0.05).