chemical and non-chemical molting methods as alternatives to continuous feed withdrawal in laying hens

an experiment was conducted to evaluate the effectiveness of chemical and non-chemical molting methods as compared to conventional feed removal methods with respect to the physiological response and postmolt performance in hy-line w36 laying hens. one hundred and eight 78-week-old hens were distributed among 27 groups of four birds and placed in cages so that the 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 three treatments (molting procedures). treatment 1 was continuous feed removal (cfr) and considered as the control. hens on treatment 2 (t2) were fed finely ground delinted whole cottonseed as the sole feed ingredient and dietary vitamin and macro and microelement levels were maintained according to hy-line w36 guideline specifications. birds on treatment 3 (t3) received a layer diet containing 5,000 ppm zn and fed at the rate of 50 g b-1 d-1. the results indicated that hens subjected to cfr, whole cotton seed and zinc supplemented diet went out of production on day 6, day 7 and day 14, respectively. continuous fasting and feeding whole cottonseed as molting programs resulted in significantly (p< 0.05) lower body weight and serum t3 concentrations but higher heterophil to lymphocyte (h:l) ratio and hematocrit, compared to the zinc method when measured on day 7. birds that received molt diet supplemented with zinc produced heavier eggs postmolt (p< 0.05) in comparison to other treatments but the egg production, egg mass and egg quality criteria were not different among the treatments.